Volvulus
Volvulus is the abnormal twisting of a segment of bowel around its mesenteric axis, leading to obstruction and potential vascular compromise with ischemia.
1. Definition
Volvulus derives from the Latin volvere, meaning "to twist." It refers to the torsion (twisting) of a segment of the alimentary tract around its own mesentery [1][2]. This twisting creates two simultaneous pathological events:
- Intestinal obstruction — the lumen is kinked shut at the point(s) of torsion.
- Vascular compromise — the mesenteric vessels (veins first, then arteries) are compressed and occluded, leading to ischaemia and, if unreduced, gangrene, perforation, and peritonitis.
Because both the bowel lumen and its blood supply are compromised, volvulus is a closed-loop obstruction — the segment is obstructed at two points with no proximal or distal outlet [2][3]. This makes it one of the most dangerous forms of intestinal obstruction; it can progress from viable bowel to full-thickness necrosis within hours.
Rotation of the colon along the axis formed by its mesentery → colon obstruction with impairment of circulation [1]
Key Concept — Closed-Loop Obstruction
A closed-loop obstruction means the bowel is blocked at two points. The trapped segment cannot decompress in either direction — intraluminal pressure rises rapidly, compressing intramural veins first (venous congestion → oedema → arterial compromise → ischaemia → necrosis → perforation). This is why volvulus is a surgical emergency: timing is everything.
2. Epidemiology
2.1 Global Perspective
- Volvulus accounts for approximately 5–8% of all intestinal obstructions in Western countries but up to 20–50% in parts of Africa, the Middle East, and South Asia (the so-called "volvulus belt"), where a high-fibre diet and chronic constipation are prevalent [2].
- Volvulus is a common cause of large bowel obstruction, second only to colorectal cancer in many series [1][5].
2.2 By Location
| Location | Frequency | Typical Patient |
|---|---|---|
| Sigmoid volvulus | ~65–70% | Older adult males, mean age ~70 y; institutionalised / psychiatric patients; high-fibre diet regions [1][2] |
| Caecal volvulus | ~25–30% | Younger females, mean age ~33–53 y [2][3] |
| Transverse colon | ~3% | Rare [2] |
| Splenic flexure | ~2% | Rare [2] |
2.3 Neonatal / Paediatric Volvulus
- In neonates, volvulus almost always means midgut volvulus secondary to malrotation [4][6][7].
- Onset classically Day 3–7 of life (contrast with duodenal atresia which presents Day 1) [8].
- Malrotation with midgut volvulus is a true neonatal surgical emergency — delay leads to catastrophic loss of the entire midgut (short-gut syndrome for life).
High Yield — Adult vs Neonatal Volvulus
In adults, think sigmoid or caecal volvulus. In neonates, think midgut volvulus from malrotation. The pathophysiology (twist → obstruction + ischaemia) is the same, but the anatomy, urgency, and management differ dramatically.
3. Anatomy and Function
3.1 Why Does Volvulus Happen Where It Happens?
For a segment of bowel to twist on itself, it needs:
- A long mesentery (mobile segment).
- A narrow mesenteric base (small pivot point around which the bowel can rotate).
- A distensible, redundant loop (provides the "lever arm" for torsion).
Sigmoid Colon
- The sigmoid colon is naturally a mobile, redundant loop with a relatively narrow mesenteric attachment.
- With chronic constipation, high-fibre diet, or ageing, the sigmoid elongates further ("redundant sigmoid"), and the mesenteric base narrows — the perfect setup for torsion.
- The two "feet" of the sigmoid (proximal descending colon and rectosigmoid junction) come close together, forming a narrow base around which the heavy, loaded loop can spin.
Caecum
- The caecum is normally retroperitoneal (fixed to the posterior abdominal wall).
- In some individuals (~10–25%), failed fusion of the ascending colon mesentery to the posterior parietal peritoneum during embryological development leaves the caecum intraperitoneal and hypermobile — it has its own mesentery and can therefore twist [3].
Midgut (Neonatal)
- Malrotation results in a short mesentery [4][6][7].
- During normal embryological development, the midgut undergoes a 270° anticlockwise rotation around the superior mesenteric artery (SMA) and then becomes fixed, creating a wide-based mesentery stretching from the ligament of Treitz (LUQ) to the ileocaecal valve (RLQ) [3].
- When this rotation is incomplete (malrotation), the mesenteric base remains abnormally narrow. The entire midgut hangs from this narrow vascular pedicle like a fan — any slight twist can occlude the SMA and its branches, causing midgut volvulus [3][4].
3.2 Vascular Anatomy
| Segment | Arterial Supply | Relevance |
|---|---|---|
| Sigmoid colon | Sigmoid arteries (branches of IMA) | Twisted mesentery occludes these → sigmoid ischaemia |
| Caecum / ascending colon | Ileocolic and right colic arteries (branches of SMA) | Torsion occludes SMA branches → right colon ischaemia |
| Midgut (neonatal) | Entire SMA territory (D2 → proximal 2/3 transverse colon) | Midgut volvulus can infarct the entire small bowel and right colon |
4. Risk Factors
4.1 Sigmoid Volvulus
| Category | Risk Factor | Mechanism |
|---|---|---|
| Anatomical | Long redundant sigmoid colon with narrow mesenteric attachment [3] | Congenital elongation provides a long lever arm for torsion |
| Dietary / Lifestyle | High-fibre diet, chronic constipation, laxative abuse [2] | Chronic faecal loading elongates and dilates the sigmoid; bulky stool acts as a "mass" that drags the loop around |
| Neuropsychiatric | Institutionalised / psychiatric patients, Parkinson's disease | Medications (anticholinergics, antipsychotics, opioids) slow motility → chronic constipation → redundant sigmoid |
| Age | Ageing [2] | Loss of mesenteric elasticity and connective tissue → stretching of bowel and mesentery |
| Immobility | Bedbound patients [2] | Reduced peristalsis → chronic constipation |
| GI Disease | Hirschsprung disease [3] | Aganglionic distal segment → chronic proximal dilatation of sigmoid; freely mobile mesosigmoid predisposes to volvulus |
| Obstetric | Pregnancy [2] | Gravid uterus displaces sigmoid superiorly; hormonal effects relax smooth muscle |
| Chagas disease | Endemic in South America | Trypanosoma cruzi destroys myenteric plexus → megacolon → volvulus |
4.2 Caecal Volvulus
| Category | Risk Factor | Mechanism |
|---|---|---|
| Congenital | Failed fusion of ascending colon mesentery to posterior peritoneum → hypermobile caecum [2][3] | Allows the caecum to twist on a mobile mesentery |
| Post-surgical | Adhesions from abdominal surgery [3] | Create fixed points around which mobile caecum can rotate |
| GI Disease | Hirschsprung disease [3] | Chronic distension can promote caecal volvulus |
| Colonoscopy / distal obstruction | Any cause of massive caecal distension | Over-distended caecum on a mobile mesentery can flip and twist |
4.3 Midgut Volvulus (Neonatal)
| Category | Risk Factor | Mechanism |
|---|---|---|
| Malrotation | Failure of normal 270° anticlockwise rotation during weeks 4–10 [3][4][6][7] | Narrow mesenteric base permits the entire midgut to twist around the SMA |
| Ladd bands | Peritoneal bands fixing abnormally positioned caecum to right lateral abdominal wall [3] | Cross over duodenum → extrinsic duodenal obstruction even without volvulus |
| Congenital diaphragmatic hernia, omphalocele, gastroschisis | Disrupted return of bowel to abdomen | Associated rotational anomalies |
5. Aetiology (with Hong Kong Focus)
In Hong Kong, the most relevant aetiologies are:
5.1 Adult Volvulus
- Sigmoid volvulus is less common in Hong Kong than in Africa/Middle East (lower fibre diet relative to those regions), but it is still the second most common cause of large bowel obstruction after colorectal cancer.
- Causes of colonic obstruction: Cancer, Volvulus, Diverticulitis, Stricture (anastomotic, radiation, ischaemic, endometriotic), Extrinsic compression (metastasis, pelvic/extraperitoneal tumour) [1][5].
- Elderly institutionalised patients (nursing homes) with chronic constipation and polypharmacy (anticholinergics, opioids) are the typical population.
- Caecal volvulus is rare but seen in younger patients post-abdominal surgery.
5.2 Neonatal Volvulus
- Malrotation with midgut volvulus is the critical diagnosis in any neonate with bilious vomiting [4][6][7][8].
- Incidence of malrotation: ~1 in 500 live births; ~75% present in the first month of life.
- In Hong Kong, most cases are identified in neonatal units at tertiary centres (Queen Mary Hospital, Prince of Wales Hospital).
6. Pathophysiology
6.1 Stepwise Pathogenesis of Volvulus
The pathophysiology follows a predictable cascade. Let's trace it step by step:
Occurs when air-filled loop of sigmoid colon twists about its mesentery → intestinal obstruction and impairment of vascular perfusion when degree of torsion exceeds 180° and 360° [3]
Key Points in the Cascade
- Torsion ≥ 180° → partial obstruction; ≥ 360° → complete obstruction + significant vascular compromise [3].
- Veins are compressed before arteries (because venous pressure is lower, ~5–10 mmHg vs arterial ~80–120 mmHg). This means:
- Arterial inflow continues while venous outflow is blocked → venous congestion → bowel wall oedema → haemorrhagic infarction (the bowel turns dark purple/black).
- Eventually, the oedema and rising intraluminal pressure also compress the arteries → full-thickness ischaemia → gangrene.
- Closed-loop mechanics: The obstructed segment cannot decompress because both ends are twisted shut. Intraluminal pressure rises rapidly. Bacterial translocation occurs through the ischaemic, permeable bowel wall → bacteraemia and endotoxaemia.
- Proximal bowel dilates with swallowed air and accumulated secretions → further fluid sequestration ("third spacing") → dehydration, hypovolaemia, electrolyte disturbances.
6.2 Specific Pathophysiology by Type
Sigmoid Volvulus
- The long, loaded sigmoid loop rotates around its narrow mesenteric pedicle (usually anticlockwise).
- The two limbs of the sigmoid approximate at the base → "coffee bean" appearance on AXR.
- Because the sigmoid is distal, vomiting is a late feature (contrast with proximal SBO where vomiting occurs early).
- Abdominal distension is massive (the trapped sigmoid loop fills with gas and can occupy the entire abdomen).
Caecal Volvulus
- Two types:
- Axial torsion (true caecal volvulus): the caecum twists on its long axis.
- Caecal bascule: the caecum folds anteriorly and superiorly (no actual twist, but still causes obstruction). Less common, less likely to cause ischaemia.
- Ischaemia occurs earlier than sigmoid volvulus because the caecal wall is thinner and distends more easily → wall tension rises (Laplace's law: wall tension = pressure × radius / wall thickness) → earlier vascular compromise.
- On AXR: the distended caecum characteristically migrates to the LUQ or epigastrium (like a "kidney-shaped" gas shadow in the wrong place).
Midgut Volvulus (Neonatal)
- Malrotation results in short mesentery → predisposes to midgut volvulus [4][6][7].
- The entire midgut (duodenum to mid-transverse colon) twists around the SMA.
- The consequences are catastrophic: ischaemia of the entire small bowel and right colon.
- Ladd bands crossing the duodenum add an element of extrinsic duodenal obstruction even before volvulus occurs [3].
- If not corrected urgently, the neonate loses the entire midgut → short gut syndrome (requires lifelong TPN or intestinal transplantation) [9].
Why Bilious Vomiting in Malrotation?
The obstruction in malrotation + midgut volvulus is at or distal to the ampulla of Vater (D2 of duodenum), where bile enters the GI tract. Therefore, the vomitus contains bile and is characteristically green or fluorescent yellow (bilious). Any neonate with bilious vomiting must be considered to have malrotation with midgut volvulus until proven otherwise — this is a surgical emergency [4][6][7][8].
7. Classification
7.1 By Anatomical Site
| Type | Site | Percentage | Key Feature |
|---|---|---|---|
| Sigmoid volvulus | Sigmoid colon | ~65–70% | Most common in adults; responds to endoscopic decompression |
| Caecal volvulus | Caecum ± ascending colon | ~25–30% | Usually requires surgery; high ischaemia rate |
| Transverse colon volvulus | Transverse colon | ~3% | Very rare; requires surgery |
| Splenic flexure volvulus | Splenic flexure | ~2% | Extremely rare |
| Midgut volvulus | Entire midgut (D2 → mid-transverse colon) | Neonatal | Always associated with malrotation |
| Gastric volvulus | Stomach | Rare in adults | Often secondary to paraesophageal (rolling-type) hiatal hernia; Borchardt's triad: severe epigastric pain, retching without vomiting, inability to pass NG tube [10] |
7.2 By Mechanism (Sigmoid and Caecal)
| Mechanism | Description |
|---|---|
| Axial torsion | Bowel rotates around its mesenteric axis (classic volvulus) |
| Bascule (caecal only) | Caecum folds anteriorly/superiorly without actual axial twist; less ischaemia risk but still causes obstruction |
7.3 Within Context of Intestinal Obstruction
- Volvulus is classified as:
Most common causes of small bowel obstruction: Adhesions, Hernias, Malignancy (ABC: Adhesion, Bulge [hernia], Cancer) [1][3][5]
Most common causes of large bowel obstruction: Cancer, Volvulus, Diverticular disease [1][3][5]
8. Clinical Features
8.1 Symptoms
The clinical presentation depends on the site, degree of torsion, and presence of ischaemia. The four cardinal features of intestinal obstruction apply [5]:
| Symptom | Pathophysiological Basis | Clinical Details |
|---|---|---|
| Abdominal pain | Torsion stretches the mesentery → visceral peritoneal irritation; closed-loop causes rapid intraluminal pressure rise; ischaemia activates nociceptors | Continuous and severe initially (mesenteric stretch + ischaemia); superimposed colicky component during peristalsis as the obstructed bowel tries to push contents past the twist [3]. In sigmoid volvulus, pain is typically lower abdominal / LIF. In caecal volvulus, pain is RIF initially but may become diffuse. Colicky pain becoming constant suggests transition from simple obstruction to ischaemia [2]. |
| Abdominal distension | The closed-loop segment traps gas (swallowed air + bacterial fermentation) and fluid; proximal bowel also dilates | Massive distension is characteristic of sigmoid volvulus (the entire sigmoid loop inflates like a balloon). Caecal volvulus causes more localised asymmetric distension. In neonatal midgut volvulus, distension may be minimal initially because the obstruction is proximal. |
| Vomiting | Proximal bowel dilates → retrograde peristalsis; vagal stimulation from mesenteric stretch | Late in sigmoid volvulus (distal obstruction — vomitus must travel retrograde through the entire colon and small bowel). Early in midgut volvulus (proximal obstruction). Bilious (green/fluorescent yellow) vomiting in neonatal midgut volvulus because obstruction is distal to ampulla of Vater [3][4][6][7][8]. |
| Absolute constipation (obstipation) | Complete luminal obstruction → no passage of flatus or faeces distally | Failure to pass both flatus and stool. Patients may report some initial passage of stool/flatus (evacuation of contents already distal to the twist) but then complete cessation. |
Additional Symptoms
| Symptom | Pathophysiological Basis |
|---|---|
| Nausea and anorexia | Vagal afferents from distended bowel → nausea centre in medulla |
| Haematochezia (bloody stool / PR bleeding) | Bowel wall ischaemia and mucosal necrosis → intraluminal haemorrhage [3] — this is a late and ominous sign indicating gangrenous bowel |
| Failure to thrive / feeding intolerance (neonatal) | Chronic partial obstruction from malrotation without acute volvulus → malabsorption [3] |
8.2 Signs
The signs on physical examination mirror the underlying pathophysiology and also help determine whether ischaemia/perforation has occurred — this distinction is critical because it changes management from conservative (endoscopic decompression) to emergency surgery.
General Examination
| Sign | Pathophysiological Basis | Clinical Significance |
|---|---|---|
| Dehydration (dry mucous membranes, reduced skin turgor, sunken eyes) | Third-space fluid loss into dilated bowel lumen and peritoneal cavity; vomiting; reduced oral intake | Assess fluid status; guides resuscitation |
| Tachycardia | Hypovolaemia → sympathetic activation; pain; sepsis (if gangrenous bowel) | Early sign of haemodynamic compromise |
| Hypotension | Severe hypovolaemia or septic shock from perforation/bacterial translocation | Late, ominous sign — suggests significant fluid deficit or established sepsis |
| Fever | Bowel ischaemia → bacterial translocation through permeable bowel wall → systemic inflammatory response | Suggests gangrenous or perforated bowel — indicates need for urgent surgery [3] |
Abdominal Examination
| Sign | Pathophysiological Basis | Clinical Significance |
|---|---|---|
| Abdominal distension | Trapped gas and fluid in closed-loop segment + proximal dilation | Sigmoid volvulus: massive, tympanitic distension, often asymmetric (the distended sigmoid loop may be palpable). Caecal volvulus: distended loop may be palpable in LUQ/epigastrium (displaced from RIF). |
| Abdominal tenderness | Mesenteric stretch; bowel wall oedema and ischaemia; peritoneal irritation | Localised initially; becomes diffuse with peritonitis. Tenderness out of proportion to examination findings may suggest ischaemia (similar to mesenteric ischaemia) [11]. |
| Visible peristalsis | Hyperperistalsis of proximal bowel trying to overcome obstruction | More common in thin patients with distal obstruction |
| Bowel sounds | Initially hyperactive / high-pitched (obstructive peristalsis → "tinkling"); later absent if ileus supervenes or bowel becomes gangrenous | Hyperactive → absent bowel sounds transition indicates progression from simple obstruction to ischaemia / paralytic phase [11] |
| Tympanic percussion | Gas-filled, distended bowel | Helps differentiate from ascites (which is dull) |
| Empty rectum on PR examination | Distal bowel is decompressed because obstruction is proximal to rectum | Classic finding in large bowel obstruction; absent rectal gas on AXR [2] |
| Peritoneal signs: Guarding, Rigidity, Rebound tenderness | Gangrenous bowel → perforation → faecal/purulent peritonitis → parietal peritoneal inflammation | Red flags indicating perforation — mandate emergency laparotomy [3]. Guarding = voluntary muscle contraction (pain). Rigidity = involuntary ("board-like abdomen") — indicates established peritonitis. Rebound tenderness = pain on release of palpation — peritoneal irritation. |
| Blood on PR examination | Mucosal ischaemia / necrosis → intraluminal bleeding | Ominous sign suggesting gangrenous bowel |
Signs Specific to Neonatal Midgut Volvulus
| Sign | Pathophysiological Basis |
|---|---|
| Bilious vomiting (the cardinal sign) | Obstruction distal to ampulla of Vater [3][4][6][7][8] |
| Abdominal distension (may be minimal) | Proximal obstruction → less distal bowel to distend |
| Erythema / discolouration of abdominal wall | Underlying gangrenous bowel → inflammation extends to parietal peritoneum and abdominal wall |
| Haemodynamic instability / shock | Hypovolaemia (dehydration, third spacing); septic shock (bowel necrosis, bacterial translocation) [3] |
| Passage of bloody stools | Ischaemic necrosis of midgut mucosa |
Clinical Pearl — Sigmoid vs Caecal Volvulus Presentation
| Feature | Sigmoid Volvulus | Caecal Volvulus |
|---|---|---|
| Age | Elderly (~70 y) | Younger (~33–53 y) |
| Sex | Male predominance | Female predominance |
| Onset | Often insidious; may have prior episodes | Usually acute |
| Distension | Massive | Moderate, asymmetric |
| Vomiting | Late | Earlier (more proximal obstruction) |
| AXR | Coffee bean sign arising from pelvis/LLQ; ahaustral; 3 converging lines | Dilated loop from RLQ, haustral markings; dilated SB |
| Rectal gas | Absent | Absent |
| Response to endoscopy | Often successful (~70–80%) | Usually unsuccessful; surgery indicated |
Red Flags — When Volvulus Has Progressed to Ischaemia / Gangrene
The following signs indicate gangrenous bowel and mandate emergency laparotomy — do NOT attempt endoscopic decompression:
- Fever, tachycardia, hypotension (septic shock)
- Peritoneal signs: guarding, rigidity, rebound tenderness (perforation + peritonitis)
- Metabolic acidosis / raised lactate (tissue ischaemia)
- PR bleeding / bloody stool (mucosal necrosis)
- Necrotic-appearing mucosa on endoscopy (if sigmoidoscopy attempted)
9. Relevant Pathophysiology of Electrolyte and Metabolic Derangements
Because volvulus causes intestinal obstruction with vomiting and third-space losses, the metabolic consequences deserve explanation [3]:
| Derangement | Mechanism |
|---|---|
| Hyponatraemia | Loss of Na⁺ and water from vomiting (gastric secretions are Na⁺-rich); third-space sequestration |
| Hypokalaemia | Direct loss of K⁺ in vomitus; metabolic alkalosis shifts K⁺ intracellularly (H⁺/K⁺ exchange); RAAS activation (hypovolaemia → aldosterone → renal K⁺ wasting); increased NaHCO₃ delivery to distal nephron → urinary K⁺ secretion |
| Metabolic alkalosis | Loss of gastric HCl through vomiting → net gain of HCO₃⁻ in blood |
| Metabolic acidosis (lactic) | Bowel ischaemia → anaerobic glycolysis → lactate production; hypovolaemia → systemic hypoperfusion → end-organ ischaemia |
| Raised serum lactate | Sensitive marker for bowel ischaemia — correlates with severity of vascular compromise |
| Leukocytosis | Bowel wall ischaemia / necrosis → inflammation → neutrophilic response |
Why Can Metabolic Alkalosis AND Metabolic Acidosis Coexist?
In early volvulus with prominent vomiting but no ischaemia yet, metabolic alkalosis predominates (loss of HCl). As ischaemia develops, lactic acidosis is superimposed. The ABG may show a mixed picture. A rising lactate in the context of volvulus is an ominous sign — it means the bowel is dying.
10. Associations and Related Conditions
10.1 Hirschsprung Disease and Volvulus
- Sigmoid volvulus can be the first presentation in Hirschsprung disease [3].
- The aganglionic segment (usually rectosigmoid) causes functional obstruction → chronic proximal sigmoid dilatation and elongation → freely mobile mesosigmoid → predisposes to volvulus.
- Hirschsprung-associated enterocolitis (HAEC) can also cause volvulus of the sigmoid or transverse colon, related to torsion of an enlarged colonic segment filled with meconium or feces [3].
10.2 Meckel Diverticulum and Volvulus
- A Meckel diverticulum can act as a lead point for volvulus of the small bowel (the diverticulum creates a fixed point around which the ileum can twist) [12].
- Can also cause intussusception or Littre's hernia.
10.3 Ischaemic Bowel and Volvulus
- Mechanical causes of ischaemic bowel: volvulus, strangulating hernia [2][5][11].
- Volvulus is both an extrinsic cause of mesenteric ischaemia (twisting of vessels) and a cause of non-occlusive ischaemia (distension → raised intraluminal pressure → reduced perfusion).
10.4 Short Gut Syndrome
- Midgut volvulus with extensive bowel necrosis requiring massive resection is a major cause of short gut syndrome (SBS) in children [9].
High Yield Summary
Definition: Volvulus = twisting of bowel around its mesentery → closed-loop obstruction + vascular compromise.
Sites: Sigmoid (~65–70%) > Caecum (~25–30%) > Transverse (~3%) > Splenic flexure (~2%). Neonates = midgut volvulus from malrotation.
Risk Factors (Sigmoid): Redundant sigmoid, chronic constipation, high-fibre diet, elderly, bedbound, neuropsychiatric patients, Hirschsprung disease.
Risk Factors (Caecal): Congenital mobile caecum (failed retroperitoneal fixation), post-surgical adhesions.
Risk Factors (Midgut): Malrotation → narrow mesenteric base → entire midgut suspended from SMA pedicle.
Pathophysiology: Torsion → venous congestion first (low pressure) → bowel wall oedema → arterial compromise → gangrene → perforation → peritonitis → septic shock.
Clinical Features: Cardinal features of IO — abdominal pain (colicky → constant = ischaemia), abdominal distension (massive in sigmoid), vomiting (late in sigmoid, early and bilious in neonatal midgut), absolute constipation.
Red Flags for Ischaemia: Fever, tachycardia, hypotension, peritonism (guarding/rigidity/rebound), metabolic acidosis/raised lactate, PR bleeding.
AXR: Sigmoid = coffee bean sign, ahaustral, arising from pelvis. Caecal = dilated haustral loop from RLQ, dilated SB.
Key Exam Point: Bilious vomiting in a neonate = malrotation with midgut volvulus until proven otherwise — surgical emergency.
Active Recall - Volvulus (Definition to Clinical Features)
1. Define volvulus and explain why it is classified as a closed-loop obstruction.
Show mark scheme
Volvulus = twisting of bowel around its mesentery. Closed-loop because the bowel is obstructed at two points (proximal and distal twist), trapping a segment with no outlet. This leads to rapid rise in intraluminal pressure, vascular compromise, and risk of ischaemia/perforation.
2. What are the two most common sites for adult colonic volvulus, and which demographic does each classically affect?
Show mark scheme
Sigmoid volvulus (65-70%): elderly males, mean age 70. Caecal volvulus (25-30%): younger females, mean age 33-53.
3. Explain the embryological basis of midgut volvulus in neonates.
Show mark scheme
Normal development: midgut rotates 270 degrees anticlockwise around SMA, then fixes to create wide mesenteric base (Treitz to ileocaecal valve). Malrotation: incomplete rotation leaves a narrow mesenteric base. Entire midgut hangs from this narrow pedicle, permitting it to twist around SMA causing midgut volvulus.
4. Why does venous congestion precede arterial compromise in volvulus?
Show mark scheme
Veins have lower intramural pressure (5-10 mmHg) compared to arteries (80-120 mmHg), so they are compressed first by the twisting mesentery. Arterial inflow continues while venous outflow is blocked, causing venous congestion, bowel wall oedema, and haemorrhagic infarction before arterial occlusion occurs.
5. A 3-day-old neonate presents with bilious vomiting. What is the most important diagnosis to exclude and why is the vomiting bilious?
Show mark scheme
Malrotation with midgut volvulus. Bilious because obstruction is distal to ampulla of Vater (D2 duodenum) where bile enters the GI tract. This is a surgical emergency; delay risks loss of entire midgut leading to short gut syndrome.
6. List three clinical signs that indicate gangrenous bowel in volvulus and mandate emergency laparotomy rather than endoscopic decompression.
Show mark scheme
Any 3 of: (1) Peritoneal signs - guarding, rigidity, rebound tenderness; (2) Fever with tachycardia and hypotension (septic shock); (3) Metabolic acidosis or raised serum lactate; (4) PR bleeding or bloody stool; (5) Necrotic mucosa seen on endoscopy.
References
[1] Lecture slides: GC 194. Intestinal obstruction colorectal cancer.pdf (p41, p60) [2] Senior notes: maxim.md (Section: Volvulus) [3] Senior notes: felixlai.md (Sections: Volvulus, Intestinal obstruction, Malrotation) [4] Lecture slides: GC 205. The newborn baby is vomiting repeatedly Neonatal intestinal obstruction and other GI emergencies.pdf (p22) [5] Lecture slides: GC 195. Lower and diffuse abdominal pain RLQ problems; pelvic inflammatory disease; peritonitis and abdominal emergencies.pdf (p28, p31) [6] Lecture slides: Neonatal Surgery.pdf (p31) [7] Lecture slides: Case Study – Paediatric Surgery Bilious vomiting of new-born _ACH Fung.pdf [8] Senior notes: maxim.md (Section: Malrotation & volvulus table) [9] Senior notes: felixlai.md (Section: Short gut syndrome) [10] Senior notes: maxim.md (Section: Gastric volvulus) [11] Senior notes: maxim.md (Section: Ischemic bowel disease) [12] Senior notes: maxim.md (Section: Meckel diverticulum)
Differential Diagnosis of Volvulus
The art of differential diagnosis in volvulus revolves around one central question: this patient has features of intestinal obstruction — is it truly a volvulus, or is something else causing the same picture? To answer this, we need to think anatomically (sigmoid volvulus mimics vs caecal volvulus mimics vs neonatal midgut volvulus mimics) and pathophysiologically (what else can cause a massively distended colon, acute abdominal pain with obstipation, or bilious vomiting in a neonate?).
The differentials are best organised by clinical context: (1) adult large bowel obstruction (sigmoid/caecal volvulus), (2) neonatal intestinal obstruction (midgut volvulus), and (3) specific mimics that deserve individual attention because they are commonly confused with volvulus on imaging or at the bedside.
1. Framework for Approaching the Differential
2. Differential Diagnosis in Adults (Sigmoid / Caecal Volvulus)
When an adult presents with abdominal distension, pain, and obstipation, volvulus must be differentiated from other causes of large bowel obstruction. The lecture slides identify the common causes of large bowel obstruction as: cancer of colon, volvulus, diverticular stricture, and pseudo-obstruction [1][5].
2.1 Obstructing Colorectal Cancer (CRC)
| Feature | How It Differs from Volvulus | Why |
|---|---|---|
| Presentation | More insidious onset with preceding change in bowel habit, weight loss, rectal bleeding, iron-deficiency anaemia | CRC grows slowly over months; obstruction is a late complication when the tumour narrows the lumen beyond a critical point |
| Age | Older adults (overlap with sigmoid volvulus age group) | CRC incidence increases with age |
| AXR | Dilated colon proximal to a transition point (often at splenic flexure or sigmoid for left-sided CRC); no coffee bean sign | The obstruction is fixed at the tumour site, not caused by twisting |
| CT abdomen | Colonic mass / wall thickening at transition point; no whirl sign | Whirl sign is pathognomonic of mesenteric twisting in volvulus |
| Competent ileocaecal valve | If present (1/3 of population), creates a closed-loop obstruction — massive caecal distension with risk of perforation, mimicking caecal volvulus [2][13] | The ileocaecal valve prevents retrograde decompression into small bowel → caecum bears the full distension load |
| Contrast enema | "Apple-core" lesion at site of CRC; bird's beak sign absent | Bird's beak = smooth tapering at the twist point (volvulus); apple-core = irregular mucosal destruction (carcinoma) |
Causes of colonic obstruction: Cancer, Volvulus, Diverticulitis, Stricture (anastomotic, radiation, ischaemic, endometriotic), Extrinsic compression (metastasis, pelvic/extraperitoneal tumour) [1]
Exam Trap — CRC Causing Closed-Loop Obstruction
A left-sided CRC in a patient with a competent ileocaecal valve can mimic caecal volvulus on AXR because the caecum becomes massively distended. The key differentiator is that in CRC-related closed-loop obstruction, the transition point is at the tumour (usually sigmoid/descending colon), not at the caecum itself. CT will show a colonic mass, not a mesenteric whirl sign. Always look for the transition point.
2.2 Toxic Megacolon
| Feature | How It Differs from Volvulus | Why |
|---|---|---|
| Definition | Total or segmental colonic dilatation with systemic toxicity [3] | An inflammatory / infectious process causes loss of colonic motor function → dilatation, NOT a mechanical twist |
| Causes | Complication of IBD, infectious colitis (especially Clostridium difficile), ischaemic colitis, volvulus itself, diverticulitis, obstructive CRC [3] | Any severe colonic inflammation can cause neuromuscular dysfunction of the colonic wall |
| Key clinical feature | Bloody diarrhoea is the most common presentation; systemic toxicity (high fever > 38.6°C, tachycardia > 120, leukocytosis > 10.5, anaemia) [3] | The underlying colitis causes mucosal ulceration and bleeding; transmural inflammation triggers SIRS |
| History | Often a history of antibiotic use (C. difficile) or known IBD | C. difficile toxin damages colonocytes; IBD flare causes transmural inflammation |
| AXR | Diffuse colonic dilatation (transverse colon > 6 cm); no coffee bean sign, no convergence of sigmoid wall lines | Dilatation is generalised, not focal to one twisted segment |
| PR exam | May pass bloody stool | In volvulus, the rectum is typically empty |
Key Distinction
Toxic megacolon = dilated colon + systemic toxicity + diarrhoea (often bloody). Volvulus = dilated colon + obstipation (no passage of stool/flatus) + NO diarrhoea. The presence of bloody diarrhoea strongly favours toxic megacolon over volvulus.
2.3 Ogilvie Syndrome (Acute Colonic Pseudo-obstruction)
| Feature | How It Differs from Volvulus | Why |
|---|---|---|
| Definition | Acute dilatation of colon in the absence of an anatomic lesion that obstructs the flow of intestinal content [3][13] | Autonomic imbalance (↓parasympathetic / ↑sympathetic) → functional aperistalsis, not a mechanical twist |
| Setting | Hospitalised patients with severe illness, post-surgery, metabolic imbalance, or on medications (opioids, CCBs) [3][13] | These conditions disrupt the autonomic regulation of colonic motility |
| Key clinical feature | Abdominal distension is the predominant symptom; relatively less pain compared to volvulus [3][13] | No mesenteric stretch or ischaemia — just a dilated, adynamic colon |
| Bowel sounds | Normal bowel sounds (key differentiator from mechanical obstruction!) [13] | There is no physical obstruction for peristalsis to struggle against |
| PR exam | Dilated rectum on PR exam (contrast with collapsed rectum in mechanical obstruction) [13] | No distal obstruction — gas can reach the rectum |
| AXR | Diffuse colonic dilatation; gas present in rectum (unlike volvulus where rectal gas is absent) [2][13] | No mechanical block → gas distributes throughout colon including rectum |
| CT | No transition point, no whirl sign; diagnosis of exclusion (must rule out mechanical cause first) | No anatomical lesion causing obstruction |
Differentiating signs of pseudo-obstruction from mechanical obstruction: normal bowel sounds; dilated rectum on PR exam [13]
2.4 Diverticular Stricture / Acute Diverticulitis
| Feature | How It Differs from Volvulus | Why |
|---|---|---|
| Mechanism | Severity ranges from diverticulitis → localised abscess → purulent peritonitis → faecal peritonitis [14] | Inflammation of a diverticulum causes pericolic oedema and fibrosis → can narrow the lumen enough to cause obstruction |
| Clinical features | Fever, tenderness and guarding, leucocytosis [14]; typically LLQ pain | Pericolic inflammation and abscess formation |
| CT | Pericolic fat stranding, colonic wall thickening > 10 cm segment, pericolonic abscess; no whirl sign | Inflammatory process, not torsion |
| Onset | More gradual; prior episodes of diverticulitis common | Chronic inflammatory process with acute-on-chronic exacerbations |
2.5 Ischaemic Bowel Disease / Ischaemic Colitis
The lecture slides list mechanical causes of ischaemic bowel (volvulus, hernia) alongside embolic, thrombotic, and non-occlusive causes [5][11]. The key issue is that volvulus itself causes ischaemia, but primary mesenteric ischaemia without volvulus can mimic a gangrenous volvulus.
| Feature | How It Differs from Volvulus | Why |
|---|---|---|
| Presentation | Generalised abdominal pain out of proportion to physical findings; PR bleeding / bloody diarrhoea [11] | Ischaemic mucosa sloughs → intraluminal bleeding; visceral peritoneum initially not involved (pain out of proportion) |
| Setting | Patient with AF (embolism), strong cardiovascular risk factors (thrombosis), or haemodynamic instability (NOMI) [11] | Each pathological mechanism has a characteristic patient profile |
| AXR | Thumbprinting (submucosal oedema/haemorrhage); may show ileus but no coffee bean or whirl sign | Mucosal and submucosal ischaemic changes, not mechanical twisting |
| CT angiography | Filling defect in SMA/IMA (embolism/thrombosis); bowel wall thickening without mesenteric whirl | Identifies the vascular cause directly |
| Lactate | Markedly elevated | Both volvulus with ischaemia and primary mesenteric ischaemia cause elevated lactate — this does NOT differentiate them; imaging is needed |
2.6 Incarcerated / Strangulated Hernia
| Feature | How It Differs from Volvulus | Why |
|---|---|---|
| Physical examination | Hernial orifices must always be examined — a tender, irreducible groin or incisional lump [5] | Bowel trapped in hernia sac → closed-loop obstruction + ischaemia |
| AXR | Small bowel dilatation (if SBO from hernia); no coffee bean sign | The obstruction is at the hernia site, not sigmoid/caecum |
| CT | Bowel loop within hernia defect; no mesenteric whirl in the abdomen | Identifies the site and nature of incarceration |
Physical Examination of large bowel obstruction: Hydration status, Tachycardia & hypotension, Abdominal tenderness, Hernial orifices, Bowel sounds, Rectal Examination [5]
Never Forget the Hernial Orifices!
It is a classic exam pitfall (and real-life disaster) to diagnose "volvulus" or "adhesive obstruction" and take the patient to theatre without checking the groins. An incarcerated inguinal or femoral hernia is the most easily correctable cause of intestinal obstruction — and the most embarrassing to miss. Always examine the hernial orifices in any patient with IO [5].
3. Differential Diagnosis in Neonates (Midgut Volvulus)
When a neonate presents with bilious vomiting, the differential includes both medical and surgical causes [7]. Midgut volvulus from malrotation is the most dangerous and must be excluded first, but several other conditions overlap in presentation.
Causes of bilious vomiting in a neonate — Medical: Sepsis, Medical NEC, CMPI, Hyponatraemia, Congenital heart disease, HIE. Surgical: Malrotation/volvulus, Anorectal malformation, Intestinal atresias, Hirschsprung's disease, Duplication cysts, Meconium ileus, Incarcerated hernia, SLCS [7]
3.1 Intestinal Atresia (Duodenal, Jejunal, Ileal, Colonic)
| Feature | How It Differs from Midgut Volvulus | Why |
|---|---|---|
| Timing | Duodenal atresia presents on Day 1 (contrast with malrotation/volvulus on Day 3–7) [8] | Complete atresia causes obstruction from birth; malrotation may not volvulise until the bowel fills with feeds |
| AXR | Double-bubble sign in duodenal atresia (dilated stomach + dilated proximal duodenum, no distal gas) [3] | Complete obstruction at D2 → air trapped in stomach and proximal duodenum |
| Contrast study | Failure of contrast to pass beyond the atresia site; no corkscrew sign | Corkscrew sign is characteristic of malrotation with volvulus |
| Associations | Duodenal atresia strongly associated with Down syndrome (Trisomy 21) [3] | Developmental association; not seen with malrotation |
| Vomiting | Bilious if atresia is distal to ampulla; non-bilious if proximal to ampulla | Same principle as volvulus — the relationship to the ampulla of Vater determines bile content |
3.2 Necrotising Enterocolitis (NEC)
| Feature | How It Differs from Midgut Volvulus | Why |
|---|---|---|
| Population | Predominantly premature infants (< 37 weeks); rare in term neonates | Immature gut barrier + immature immune system + abnormal bacterial colonisation |
| Onset | Usually after initiation of enteral feeds; timing variable (days to weeks) | Enteral feeds provide substrate for pathological bacterial fermentation in immature gut |
| Clinical features | Abdominal distension, bilious vomiting, bloody stools, pneumatosis intestinalis on AXR (intramural gas) | Gas produced by bacteria invading the ischaemic bowel wall — pathognomonic of NEC |
| AXR | Pneumatosis intestinalis, portal venous gas, NO coffee bean or whirl sign | Gas in bowel wall (not lumen) differentiates NEC from volvulus |
| Systemic | More prominent systemic features early: apnoea, bradycardia, temperature instability, metabolic acidosis | Gut barrier failure → bacterial translocation → sepsis |
3.3 Hirschsprung Disease
| Feature | How It Differs from Midgut Volvulus | Why |
|---|---|---|
| Presentation | Failure to pass meconium within 48 hours; progressive abdominal distension; late bilious vomiting | Aganglionic segment (usually rectosigmoid) causes functional distal obstruction from birth |
| PR exam | Explosive passage of gas and meconium on rectal examination ("squirt sign") | The examining finger dilates the aganglionic spastic segment, releasing trapped proximal contents |
| Contrast enema | Transition zone between narrow distal aganglionic segment and dilated proximal normal colon | The ganglionated segment dilates because it receives contents it cannot pass through the aganglionic segment |
| Definitive diagnosis | Rectal suction biopsy showing absent ganglion cells in submucosa | Histological confirmation is required |
3.4 Meconium Ileus
| Feature | How It Differs from Midgut Volvulus | Why |
|---|---|---|
| Association | Strongly associated with cystic fibrosis (CF) | Thick, inspissated meconium due to defective CFTR chloride channel → reduced water secretion into GI lumen |
| AXR | Dilated small bowel loops; "soap-bubble" / ground-glass appearance in RLQ (air mixed with thick meconium) | Viscid meconium has a characteristic mottled appearance when mixed with air |
| Contrast enema | Microcolon (unused colon) with meconium pellets in terminal ileum | The colon is small because thick meconium obstructs the ileum and never reaches the colon |
3.5 Other Neonatal Differentials
| Condition | Key Distinguishing Feature |
|---|---|
| Duplication cysts | Fluid-filled cystic mass on ultrasound; may act as lead point for intussusception or volvulus |
| Incarcerated inguinal hernia | Palpable groin mass; more common in premature males |
| Anorectal malformation | Absent or abnormally positioned anus on perineal inspection — should be identified on routine newborn examination |
| Sepsis, HIE, CMPI, hyponatraemia, congenital heart disease | Medical causes of bilious vomiting — systemic signs predominate (lethargy, poor perfusion, abnormal neurology); no mechanical obstruction on imaging [7] |
4. Summary Table — Key Differentiators
| Condition | Key AXR Finding | Key CT Finding | Key Clinical Clue | Bowel Sounds | Rectal Gas |
|---|---|---|---|---|---|
| Sigmoid volvulus | Coffee bean sign; ahaustral; 3 converging lines from pelvis [2] | Whirl sign, bird's beak [3] | Elderly, constipated, massive distension | Hyperactive → absent | Absent |
| Caecal volvulus | Dilated haustral loop from RLQ, displaced; dilated SB [2] | Whirl sign around ileocolic vessels [3] | Younger female, post-surgery | Hyperactive → absent | Absent |
| Obstructing CRC | Dilated colon to transition point; no coffee bean | Mass at transition point | Weight loss, altered bowel habit, rectal bleeding | Hyperactive | Absent (if complete) |
| Toxic megacolon | Diffuse colonic dilatation; transverse colon > 6 cm | Colonic wall thickening, no whirl | Bloody diarrhoea, systemic toxicity | Absent | Present |
| Ogilvie syndrome | Diffuse colonic dilatation; gas in rectum | No transition point, no mass | Hospitalised, post-op, less pain | Normal | Present |
| Diverticular stricture | Dilated colon to sigmoid; no coffee bean | Fat stranding, wall thickening, ± abscess | Fever, LLQ tenderness, leucocytosis [14] | Variable | Absent (if complete) |
| Ischaemic colitis | Thumbprinting; no coffee bean | Wall thickening at watershed zones | Pain out of proportion, AF, PR bleeding [11] | Absent (paralytic phase) | Variable |
| Malrotation + midgut volvulus | Dilated stomach, no distal gas | Whirl sign around SMA | Bilious vomiting, neonate Day 3–7 [8] | Variable | Variable |
| Duodenal atresia | Double-bubble sign | — | Bilious vomiting Day 1, Down syndrome | Absent distally | Absent |
| NEC | Pneumatosis intestinalis, portal venous gas | Pneumatosis, portal gas | Premature infant, bloody stools | Absent | Variable |
| Hirschsprung | Dilated proximal colon, narrow distal | Transition zone | Failure to pass meconium within 48 h | Present | Explosive on PR |
5. Approach to Narrowing the Differential
The following clinical and investigative features help you narrow the differential efficiently:
- Check the AXR pattern first — coffee bean sign is virtually diagnostic of sigmoid volvulus. Dilated caecum in LUQ suggests caecal volvulus.
- Is there rectal gas? Absent rectal gas → mechanical obstruction (volvulus, CRC, stricture). Present rectal gas → consider pseudo-obstruction (Ogilvie syndrome).
- PR examination — empty rectum (mechanical LBO); dilated rectum (pseudo-obstruction); explosive decompression (Hirschsprung); blood (ischaemia, CRC, NEC).
- Is the patient a neonate? Bilious vomiting in a neonate = malrotation with midgut volvulus until proven otherwise [7][8]. Get an urgent contrast meal study.
- Systemic toxicity + bloody diarrhoea? Think toxic megacolon rather than volvulus.
- CT with whirl sign is highly specific for volvulus — if absent, reconsider diagnosis.
High Yield Summary — Differential Diagnosis of Volvulus
Adult sigmoid volvulus DDx: Obstructing CRC, toxic megacolon, Ogilvie syndrome, diverticular stricture, ischaemic colitis, incarcerated hernia.
Key differentiators: Coffee bean sign + absent rectal gas + obstipation = volvulus. Bloody diarrhoea + systemic toxicity = toxic megacolon. Normal bowel sounds + gas in rectum + hospitalised = Ogilvie. Mass at transition point = CRC.
Neonatal midgut volvulus DDx: Duodenal atresia (Day 1, double-bubble), NEC (premature, pneumatosis), Hirschsprung (failure to pass meconium), meconium ileus (CF, microcolon), plus medical causes (sepsis, CMPI, HIE, hyponatraemia, CHD).
Golden rule: Bilious vomiting in neonate = malrotation with midgut volvulus until proven otherwise. Always check hernial orifices in any IO.
Active Recall - Differential Diagnosis of Volvulus
1. Name four common causes of large bowel obstruction that must be differentiated from sigmoid volvulus.
Show mark scheme
Colorectal cancer, diverticular stricture, Ogilvie syndrome (pseudo-obstruction), toxic megacolon. Also acceptable: incarcerated hernia, ischaemic stricture.
2. How do you differentiate Ogilvie syndrome from sigmoid volvulus on AXR and PR examination?
Show mark scheme
Ogilvie: diffuse colonic dilatation with gas present in rectum; dilated rectum on PR exam; normal bowel sounds. Sigmoid volvulus: coffee bean sign arising from pelvis; absent rectal gas; empty rectum on PR; hyperactive then absent bowel sounds.
3. A neonate presents with bilious vomiting on Day 4 of life. What is the most important diagnosis to exclude, and what investigation would you request urgently?
Show mark scheme
Malrotation with midgut volvulus. Urgent upper GI contrast study (contrast meal / follow-through) to assess position of DJ junction. Abnormal DJ junction or corkscrew appearance confirms malrotation.
4. What AXR finding is pathognomonic for NEC and differentiates it from midgut volvulus?
Show mark scheme
Pneumatosis intestinalis (intramural gas within the bowel wall). May also see portal venous gas. These are not seen in simple midgut volvulus.
5. A patient with sigmoid volvulus has bloody diarrhoea and high fever. What alternative diagnosis should you consider, and what is the key distinguishing pathological feature?
Show mark scheme
Toxic megacolon. Key feature: systemic toxicity (fever >38.6C, tachycardia >120, leucocytosis, anaemia) plus bloody diarrhoea from underlying colitis (IBD, C. difficile). Volvulus causes obstipation, not diarrhoea. Toxic megacolon shows diffuse colonic dilatation without coffee bean sign.
6. Why must you always examine the hernial orifices in a patient presenting with intestinal obstruction?
Show mark scheme
An incarcerated inguinal or femoral hernia is a common and easily correctable cause of intestinal obstruction. If missed, it can progress to strangulation, bowel necrosis, and perforation. A tender irreducible groin lump clinches the diagnosis and changes management immediately.
References
[1] Lecture slides: GC 194. Intestinal obstruction colorectal cancer.pdf (p41, p60) [2] Senior notes: maxim.md (Section: Volvulus) [3] Senior notes: felixlai.md (Sections: Volvulus, Intestinal atresia, Hirschsprung disease) [5] Lecture slides: GC 195. Lower and diffuse abdominal pain RLQ problems; pelvic inflammatory disease; peritonitis and abdominal emergencies.pdf (p28, p31) [7] Lecture slides: Case Study – Paediatric Surgery Bilious vomiting of new-born _ACH Fung.pdf (p51) [8] Senior notes: maxim.md (Section: Malrotation & volvulus table) [11] Senior notes: maxim.md (Section: Ischemic bowel disease) [13] Senior notes: maxim.md (Section: Pseudo-obstruction / Ogilvie syndrome) [14] Lecture slides: GC 195. Lower and diffuse abdominal pain RLQ problems; pelvic inflammatory disease; peritonitis and abdominal emergencies.pdf (p19)
Diagnostic Criteria, Diagnostic Algorithm, and Investigation Modalities for Volvulus
1. Diagnostic Criteria — Does Volvulus Have Formal "Criteria"?
Unlike conditions such as rheumatic fever or SLE, volvulus does not have formalised diagnostic criteria with a scoring system. Instead, the diagnosis is established through a combination of:
- Clinical suspicion based on the presentation (cardinal features of IO in the right demographic context).
- Radiological confirmation — this is where the diagnosis is truly made.
The clinical picture raises the alarm; the imaging seals the deal. Let's think about this from first principles: volvulus is an anatomical event (a twist), so you need an investigation that can visualise the twist or its consequences — that's radiology and endoscopy.
For neonatal midgut volvulus, the diagnostic standard is even more time-critical: time is essence [4] — you cannot wait for elaborate workups.
2. Diagnostic Algorithm
The following algorithm represents the systematic approach to a patient with suspected volvulus, integrating clinical assessment, resuscitation, and stepwise investigations. It separates the adult pathway (sigmoid/caecal) from the neonatal pathway (midgut).
2.1 Adult Volvulus Diagnostic Algorithm
2.2 Neonatal Midgut Volvulus Diagnostic Algorithm
Approach: Expedited but thorough clinical evaluation. Vital signs, perfusion, hydration status. Exam: Abdominal distension, discolouration, tenderness, mass, bowel sounds; normal anus, hernia. Labs: electrolytes, glucose, urea, creatinine, CBC, urinalysis, capillary blood gas. XRs: AXR supine, cross table lateral. OGT insertion, IV, bolus fluid. Further Ix ± intervention according to DDx [7]
Time is Essence in Neonatal Midgut Volvulus
Time is essence [4]. In neonatal midgut volvulus, every hour of delay increases the risk of irreversible midgut infarction. If the clinical suspicion is high (bilious vomiting in an otherwise well neonate who then deteriorates), do NOT wait for contrast studies — take the baby to theatre. A negative laparotomy is far better than a dead bowel. The upper GI contrast study is done when you have time and doubt, not when the baby is in extremis.
3. Investigation Modalities — Detailed Breakdown
The investigations for volvulus follow the standard surgical principle: bedside → bloods → imaging → endoscopy. The lecture slides outline the general framework for investigating intestinal obstruction: Blood tests, Plain abdominal X-ray (SBO: valvulae conniventes, central; LBO: haustra, peripheral), CT (level of obstruction, cause, viability of bowel, presence of metastasis if malignant cause), Contrast study (Gastrografin follow-through / enema) [15].
Let's also integrate the general investigation framework from the lecture slides: Bedside tests: Urinalysis, pregnancy test. Blood tests: Blood count, renal and liver function, amylase, clotting profile, arterial blood gas, type and screen. Imaging: Erect CXR, erect and supine AXR, USG, CT, contrast studies. Endoscopy: Colonoscopy, upper endoscopy [16].
3.1 Bedside Tests
| Test | Purpose | Key Findings | Explanation |
|---|---|---|---|
| Urinalysis | Rule out urological causes of abdominal pain (renal colic, UTI) [16] | Normal in volvulus | Volvulus is a surgical cause; urinalysis helps exclude medical mimics |
| Pregnancy test | Mandatory in females of reproductive age [16] | Rule out ectopic pregnancy | Abdominal pain + vomiting in a young woman — always exclude pregnancy before imaging/surgery |
| PR examination | Assess rectal contents and tone | Empty rectum with no gas = mechanical LBO; blood on glove = mucosal ischaemia/necrosis | In volvulus, the obstruction is proximal to the rectum, so the rectum is empty and collapsed. Blood suggests gangrenous bowel. |
3.2 Blood Tests (Laboratory Investigations)
Labs: electrolytes, glucose, urea, creatinine, CBC, urinalysis, capillary blood gas [7]
| Investigation | Key Findings in Volvulus | Pathophysiological Explanation |
|---|---|---|
| CBC with differentials [3] | Leukocytosis (raised WCC) | Bowel wall ischaemia → inflammatory cascade → neutrophil mobilisation from bone marrow. A markedly elevated WCC (> 15–20 × 10⁹/L) with left shift suggests gangrenous bowel or established sepsis. |
| RFT (Renal function tests: urea, creatinine, electrolytes) [3] | Hyponatraemia: Na⁺ < 135 mmol/L | Loss of Na⁺ and water from vomiting (gastric secretions contain ~60 mmol/L Na⁺) + third-space sequestration into dilated bowel and peritoneal cavity → total body Na⁺ depletion. |
| Hypokalaemia: K⁺ < 3.5 mmol/L | Multiple mechanisms: (1) Direct K⁺ loss in vomitus; (2) Metabolic alkalosis from vomiting shifts K⁺ intracellularly (H⁺/K⁺ exchange); (3) Increased plasma HCO₃⁻ exceeds resorptive threshold → increased NaHCO₃ delivery to distal nephron → enhanced urinary K⁺ secretion; (4) Hypovolaemia → RAAS activation → aldosterone → renal K⁺ wasting [3]. | |
| Raised urea (pre-renal pattern: urea↑ > creatinine↑) | Dehydration/hypovolaemia → reduced renal perfusion → increased urea reabsorption in proximal tubule | |
| LFT [3] | Usually normal | Ordered to rule out hepatobiliary causes of abdominal pain |
| Serum amylase [3] | Usually normal; may be mildly elevated | Rule out acute pancreatitis; mild elevation can occur with bowel ischaemia (non-specific) |
| Serum lactate [3][11] | Elevated (> 2 mmol/L) | Sensitive marker for bowel ischaemia [3]. Anaerobic glycolysis in ischaemic bowel wall → lactate production. A rising lactate is an ominous sign suggesting progression from reversible ischaemia to irreversible necrosis. |
| Arterial blood gas (ABG) [3][11] | Metabolic acidosis (lactic acidosis: high anion gap) | Bowel ischaemia → anaerobic metabolism → lactic acid accumulation; also reflects systemic hypoperfusion if the patient is hypovolaemic. HAGMA (high anion gap metabolic acidosis) [11]. |
| Metabolic alkalosis (may coexist) | Vomiting of gastric HCl → net loss of H⁺ → rise in plasma HCO₃⁻. In early volvulus with prominent vomiting but no ischaemia yet, alkalosis may predominate [3]. | |
| Clotting profile [16] | Check for coagulopathy | Pre-operative assessment; DIC may develop with advanced bowel gangrene and sepsis |
| Type and screen / Group & save [16] | Blood group + antibody screen | Pre-operative preparation — surgery may be needed urgently |
The Lactate-ABG Axis — What It Tells You
In any patient with suspected volvulus, the lactate and ABG together give you the most important information about bowel viability:
- Normal lactate + metabolic alkalosis → early volvulus, vomiting predominant, bowel likely still viable → attempt endoscopic decompression.
- Rising lactate + metabolic acidosis (HAGMA) → bowel ischaemia progressing → this patient needs surgery, not a sigmoidoscope.
- Very high lactate (> 5 mmol/L) + severe acidosis → established gangrene, likely perforation imminent → emergency laparotomy.
3.3 Imaging
A. Erect Chest X-Ray (CXR)
| Finding | Significance | Why |
|---|---|---|
| Free gas under diaphragm (pneumoperitoneum) [3] | Bowel perforation | Gas escapes from perforated bowel into peritoneal cavity → rises to highest point (under diaphragm in upright position). If present, skip further imaging — go to emergency laparotomy. |
| NG tube position | Confirm correct placement | Essential for drip-and-suck management |
| Basal atelectasis / aspiration pneumonia | Complication of vomiting / distension | Diaphragmatic splinting from massive distension; aspiration of vomitus |
Erect CXR: Look for free gas under diaphragm [3]
B. Plain Abdominal X-Ray (AXR) — Erect and Supine
The AXR is the first-line imaging investigation for suspected volvulus and is often diagnostic, especially for sigmoid volvulus. Understanding what you see requires knowing the difference between small and large bowel on AXR:
- Small bowel: valvulae conniventes (thin, complete mucosal folds crossing the entire width), central position [15].
- Large bowel: haustra (thick, incomplete folds that do NOT cross the full width), peripheral position [15].
AXR Findings — Sigmoid Volvulus vs Caecal Volvulus:
| Feature | Sigmoid Volvulus | Caecal Volvulus |
|---|---|---|
| Origin | Arises from pelvis / LLQ [2] | Arises from RLQ [2] |
| Haustral markings | Ahaustral (the sigmoid is so distended that haustral markings are effaced) [2] | Haustral (the caecum retains its haustral markings even when distended) [2] |
| Characteristic sign | Coffee bean sign — U-shaped, massively distended sigmoid loop extending from pelvis towards RUQ; the two walls of the loop pressed together create a central dense line [1][2][3] | Coffee bean sign — but the dilated caecum is displaced medially and superiorly (often to LUQ or epigastrium) [3] |
| Convergence | 3 lines of sigmoid wall converging to site of obstruction (the two outer walls + the central crease) [2] | Not described |
| Proximal bowel | Dilated large bowel proximal to sigmoid [3] | Dilated small bowel with decompressed colon distal to caecum [2][3] |
| Rectal gas | Absent [2] | Absent [2] |
| Air-fluid levels | Present [3] | Present [3] |
X-rays: dilated sigmoid (coffee bean) [1]
AXR Findings — Complications:
| Finding | Significance | Description |
|---|---|---|
| Thumbprinting sign [3] | Bowel wall ischaemia | Submucosal oedema/haemorrhage thickens the haustral folds at regular intervals, projecting into the lumen like thumbprints |
| Pneumatosis intestinalis [3] | Bowel wall necrosis | Gas produced by bacteria that have invaded the necrotic bowel wall — appears as linear or bubbly lucencies within the bowel wall |
| Pneumoperitoneum / Free gas under diaphragm [3] | Perforation | Gas escaped from perforated bowel into peritoneal cavity |
| Rigler sign (Double-wall sign) [3] | Perforation | Both the inner (luminal) and outer (serosal) surfaces of the bowel wall are outlined by gas — possible only when there is gas on BOTH sides of the bowel wall (i.e., extraluminal gas present) |
Why Is the Coffee Bean Sign So Characteristic?
Imagine the sigmoid colon as a U-shaped loop. When it twists, the two limbs of the U come together and the loop inflates with trapped gas like a balloon. On AXR, you see a massively dilated, ahaustral, ovoid gas shadow extending from the pelvis upward, with a central dense line where the two walls of the loop are pressed against each other. The overall shape resembles a coffee bean — hence the name. The three converging lines at the base of the bean represent the two outer walls and the central crease converging at the point of torsion.
C. CT Abdomen with Contrast
CT is the gold standard for adult volvulus when the AXR is non-diagnostic, and is increasingly used as the first-line cross-sectional study. It provides information on level of obstruction, cause, viability of bowel, and presence of metastasis if malignant cause [15].
| Finding | Type | Significance |
|---|---|---|
| Whirl sign | Sigmoid and caecal | Dilated sigmoid colon twisting around its mesocolon and vessels [2][3] — the mesentery and mesenteric vessels spiral around the point of torsion, creating a swirling pattern on axial cuts. Pathognomonic of volvulus. For caecal volvulus: twisting of mesentery around ileocolic vessels [3]. |
| Bird-beak sign | Sigmoid | Bird-beak appearance of the afferent and efferent colonic segments [2][3] — the two limbs of the sigmoid taper smoothly towards the point of torsion, converging like a bird's beak |
| Absence of rectal gas | Both | Confirms complete distal obstruction [3] |
| Transition point | Both | Identifies the exact level where dilated proximal bowel transitions to collapsed distal bowel |
| CT findings of ischaemia | ||
| Pneumatosis intestinalis | Gas within the bowel wall — indicates necrosis [3] | |
| Bowel wall thickening | Oedema and congestion from venous obstruction [3] | |
| Reduced or lack of bowel wall enhancement | Arterial compromise → poor perfusion → bowel wall does not enhance with IV contrast [3] | |
| Oedematous and thickened mesentery | Venous congestion and inflammatory fluid in the mesentery [3] | |
| Engorgement of mesenteric vessels | Venous outflow obstruction → distended, engorged veins [3] | |
| Portal venous gas | Gas from necrotic bowel wall enters mesenteric veins → portal system — a very late and ominous sign [3] |
CT (only if AXR / enema inconclusive): whirl sign [2]
D. Contrast Enema (Water-Soluble / Gastrografin or Barium)
| Feature | Details |
|---|---|
| Indications | Reserved when AXR or CT abdomen is NOT diagnostic, provided there is no evidence of peritonitis on physical examination [3] |
| Contraindication | Suspected perforation or peritonitis — introducing contrast into a perforated bowel worsens contamination |
| Sigmoid volvulus finding | Bird-beak sign — contrast tapers smoothly to the point of obstruction where the sigmoid twist narrows the lumen [2][3] |
| Therapeutic potential | Can occasionally reduce a volvulus (hydrostatic pressure from the contrast may untwist the sigmoid), but this is unreliable and the primary purpose is diagnostic [3] |
| Risk | Rarely used given the risk of perforation in volvulus [3] |
| Contrast type | Water-soluble contrast (gastrografin) is preferred over barium — if perforation occurs, barium causes severe chemical peritonitis, whereas gastrografin is absorbed and is less harmful |
E. Upper GI Contrast Study (for Neonatal Midgut Volvulus)
This is a completely different investigation from the contrast enema used in adults. It is the gold standard for diagnosing malrotation and midgut volvulus in neonates [3].
| Feature | Details |
|---|---|
| What it is | Upper GI contrast series (barium meal / small bowel follow-through / small bowel enema) [3] — contrast is administered orally or via NG/OG tube and its passage through the duodenum and proximal jejunum is fluoroscopically observed |
| Why it is the gold standard | GOLD STANDARD — best to visualise the duodenum [3]. The key diagnostic question is: "Where is the DJ junction (ligament of Treitz)?" In normal anatomy, the DJ junction is in the LUQ, to the left of the vertebral column. In malrotation, it is displaced to the right or midline. |
| Classical findings | Corkscrew appearance in the duodenum (the duodenum spirals around the SMA rather than crossing normally from right to left) [3] |
| Beak appearance where contrast tapers to a point at the site of volvulus [3] | |
| Dilatation of stomach and proximal duodenum in duodenal obstruction (from Ladd bands or volvulus) [3] | |
| Clearly misplaced duodenum with ligament of Treitz on right side of abdomen [3] | |
| When to do it | If in doubt [4] — when clinical suspicion exists but AXR is not conclusive. If the baby is critically ill with clear peritonitis or shock, skip this and go straight to theatre. |
Diagnosis: AXR. Upper GI contrast if in doubt. Time is essence. [4]
Neonatal Investigations — Contrast Meal NOT Contrast Enema
A common mistake is to order a contrast enema for a neonate with suspected malrotation. The pathology is in the duodenum (DJ junction position, duodenal obstruction by Ladd bands), so you need an upper GI contrast study that traces the duodenum, not a lower GI study. A contrast enema can show the caecal position (which may be abnormal in malrotation), but this is unreliable — up to 20% of malrotation cases have a normally positioned caecum on enema.
F. CT Abdomen with Contrast (Neonatal — Supplementary)
| Feature | Details |
|---|---|
| Role | Used in evaluation of abdominal pain but is NOT the best test to evaluate for intestinal malrotation [3] — upper GI contrast study is superior |
| Findings | Whirlpool sign (twisting of blood vessels around mesenteric pedicle) [3]; proximal SB mostly to the right of midline; 3rd part of duodenum does not pass between mesenteric artery and aorta; abnormal position of SMA and SMV (SMA/SMV reversal — the SMV is normally to the right of the SMA; in malrotation, the relationship is altered) [3] |
| Limitation | Radiation exposure in neonates; less dynamic than fluoroscopic upper GI study |
3.4 Endoscopy
Endoscopy in volvulus serves a dual role — both diagnostic AND therapeutic. The choice of endoscopy depends on the location of the volvulus [2]:
| Endoscope | Volvulus Type | Diagnostic Role | Therapeutic Role |
|---|---|---|---|
| Flexible sigmoidoscopy [2] | Sigmoid volvulus | Visualise twisted mucosa; assess viability (pink = viable; dark/necrotic = gangrenous → abandon and go to surgery) | De-rotation with cautious insufflation (first line!) [2] — the scope is gently advanced past the twist, decompressing the obstructed loop. Successful reduction is signalled by sudden expulsion of gas and stool [2]. |
| Colonoscopy [2] | Caecal volvulus | Visualise the twist; assess viability | Colonoscopic de-rotation ± caecopexy — but this has a high recurrence rate and is generally not preferred; surgery (right hemicolectomy) is the definitive treatment [2] |
Key points about endoscopy:
- Contraindicated if suspected perforation (e.g., toxic megacolon) [17] — insufflation of air into a perforated bowel is catastrophic.
- If necrotic mucosa is visualised during sigmoidoscopy → abandon the procedure immediately and proceed to emergency laparotomy [2].
- After successful endoscopic decompression of sigmoid volvulus: leave rectal tube in situ for 24 hours for ongoing decompression → serial AXR to monitor [2].
Endoscopy: sigmoidoscopy (sigmoid), colonoscopy (caecal) [2]
Colonoscopy — Therapeutic indication: Volvulus (decompression) [17]
4. Summary — Investigation Pathway at a Glance
| Step | Investigation | What You're Looking For | When |
|---|---|---|---|
| 1 | Bedside: PR exam, urinalysis, pregnancy test | Empty rectum, blood, exclude other causes | Immediately |
| 2 | Bloods: CBC, RFT, LFT, amylase, lactate, ABG, clotting, G&S | Leukocytosis, electrolyte derangement, metabolic acidosis, raised lactate (ischaemia), pre-op workup | Immediately |
| 3 | Erect CXR | Free gas under diaphragm (perforation → straight to theatre) | First imaging |
| 4 | AXR erect + supine | Coffee bean sign (sigmoid), dilated caecum (caecal), air-fluid levels, ischaemia signs (thumbprinting, pneumatosis), absent rectal gas | First-line for diagnosis |
| 5 | CT abdomen with contrast | Whirl sign, bird-beak sign, transition point, ischaemia features, exclude other causes | If AXR non-diagnostic or to assess viability/complications |
| 6 | Contrast enema (gastrografin) | Bird-beak sign; may reduce volvulus | Only if AXR and CT non-diagnostic AND no peritonitis |
| 7 | Flexible sigmoidoscopy / colonoscopy | Mucosal viability; therapeutic decompression | Sigmoid: first-line treatment; Caecal: rarely successful |
| Neonatal | Upper GI contrast study | Corkscrew sign, beak sign, DJ junction position | Gold standard for malrotation; do urgently if in doubt |
High Yield Summary — Diagnosis of Volvulus
AXR is the first-line investigation.
- Sigmoid: coffee bean sign, ahaustral, 3 converging lines, arises from pelvis/LLQ, absent rectal gas
- Caecal: dilated haustral caecum from RLQ, dilated SB, absent rectal gas
CT abdomen if AXR non-diagnostic: whirl sign (pathognomonic), bird-beak sign, assess for ischaemia (pneumatosis, reduced wall enhancement, portal venous gas).
Contrast enema: bird-beak sign; reserved for non-diagnostic AXR/CT; contraindicated if peritonitis.
Endoscopy: Sigmoidoscopy (sigmoid volvulus — first-line treatment); colonoscopy (caecal — usually not successful).
Neonatal: Upper GI contrast study is gold standard — corkscrew sign, abnormal DJ junction. Time is essence.
Bloods: Lactate + ABG are the most important for assessing bowel viability. Rising lactate + HAGMA = ischaemia = surgery.
Red flags on AXR: Pneumatosis intestinalis, portal venous gas, Rigler sign → gangrene/perforation → emergency laparotomy, NOT endoscopy.
Active Recall - Diagnosis of Volvulus
1. Describe the coffee bean sign on AXR. What causes this appearance and which type of volvulus is it associated with?
Show mark scheme
Coffee bean sign = massively dilated, ahaustral, ovoid sigmoid loop extending from pelvis to RUQ with a central dense line where the two walls are pressed together. Caused by the U-shaped sigmoid twisting and inflating with trapped gas. Pathognomonic of sigmoid volvulus. Three converging lines at the base represent the two outer walls and central crease at the torsion point.
2. What is the whirl sign on CT and why is it pathognomonic of volvulus?
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Whirl sign = the mesentery and mesenteric vessels spiralling around the point of torsion on axial CT cuts. Pathognomonic because it directly visualises the twisting of the mesentery that defines volvulus. In sigmoid volvulus: sigmoid colon twists around mesocolon and vessels. In caecal volvulus: mesentery twists around ileocolic vessels.
3. A neonate with bilious vomiting has a non-diagnostic AXR. What is the gold standard investigation and what are two classical findings?
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Gold standard: Upper GI contrast study (barium meal / small bowel follow-through). Classical findings: (1) Corkscrew appearance of the duodenum (duodenum spirals around SMA instead of crossing normally); (2) Abnormal position of DJ junction (ligament of Treitz) on the right side instead of LUQ. Also: beak appearance at site of volvulus, dilatation of stomach and proximal duodenum.
4. Name three AXR findings that indicate bowel ischaemia or perforation in volvulus and mandate emergency laparotomy.
Show mark scheme
Any 3 of: (1) Pneumatosis intestinalis (gas within bowel wall = necrosis); (2) Portal venous gas (very late sign of necrosis); (3) Thumbprinting sign (submucosal oedema/haemorrhage from ischaemia); (4) Pneumoperitoneum / free gas under diaphragm (perforation); (5) Rigler sign / double-wall sign (perforation).
5. Explain why serum lactate and ABG are the most important blood tests for determining management in volvulus.
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Serum lactate is a sensitive marker for bowel ischaemia - produced by anaerobic glycolysis in ischaemic bowel wall. ABG shows metabolic acidosis (HAGMA from lactic acidosis) when bowel is ischaemic. Together, rising lactate plus HAGMA indicate that the bowel is dying and endoscopic decompression is insufficient - the patient needs emergency surgery. Conversely, normal lactate with metabolic alkalosis from vomiting suggests viable bowel amenable to endoscopic treatment.
6. Why is a contrast enema contraindicated in volvulus with peritonitis, and why is water-soluble contrast preferred over barium?
Show mark scheme
Contraindicated with peritonitis because introducing contrast into a perforated bowel worsens peritoneal contamination. Water-soluble contrast (gastrografin) preferred because if perforation occurs, it is absorbed by the peritoneum and causes minimal harm. Barium is inert and not absorbed - it causes severe chemical peritonitis (barium peritonitis) which is potentially fatal.
References
[1] Lecture slides: GC 194. Intestinal obstruction colorectal cancer.pdf (p60) [2] Senior notes: maxim.md (Section: Volvulus) [3] Senior notes: felixlai.md (Sections: Volvulus — Diagnosis, Intestinal malrotation — Diagnosis, Intestinal obstruction — Diagnosis) [4] Lecture slides: GC 205. The newborn baby is vomiting repeatedly Neonatal intestinal obstruction and other GI emergencies.pdf (p22, p23) [7] Lecture slides: Case Study – Paediatric Surgery Bilious vomiting of new-born _ACH Fung.pdf (p52) [11] Senior notes: maxim.md (Section: Ischemic bowel disease — Investigations) [15] Lecture slides: GC 195. Lower and diffuse abdominal pain RLQ problems; pelvic inflammatory disease; peritonitis and abdominal emergencies.pdf (p29) [16] Lecture slides: GC 195. Lower and diffuse abdominal pain RLQ problems; pelvic inflammatory disease; peritonitis and abdominal emergencies.pdf (p12) [17] Senior notes: maxim.md (Section: Colonoscopy — indications and contraindications)
Management of Volvulus
1. General Principles
The management of volvulus follows a logical cascade that every surgeon thinks through — sometimes in seconds at 3 AM:
- Is the patient dying right now? → Resuscitate first (ABC).
- Is the bowel dying? → If yes, emergency laparotomy — no time for endoscopy.
- Can I decompress non-operatively? → If sigmoid volvulus without ischaemia, try endoscopic decompression first.
- How do I prevent recurrence? → Definitive surgery (elective resection) for appropriate patients.
The fundamental decision tree splits on two axes:
- Site: Sigmoid vs Caecal vs Midgut (neonatal) — because the management differs dramatically.
- Bowel viability: Viable (no ischaemia) vs Compromised (ischaemia/gangrene/perforation) — because this determines whether you can attempt conservative measures or must operate immediately.
2. Management Algorithm — Overview (Mermaid)
3. Initial Resuscitation (All Types)
Before any definitive treatment — whether endoscopic or surgical — every patient with volvulus needs simultaneous resuscitation. This is the "drip and suck" approach familiar from any intestinal obstruction [2][3][18]:
Initial: NPO, drip & suck, IV antibiotics [2]
Non-operative treatment: Intravenous fluid and electrolytes, Nasogastric decompression, Nutrition when prolonged fasting is anticipated, Frequent monitor of vital signs, abdominal signs and X-rays [18]
| Measure | Rationale | Details |
|---|---|---|
| Nil per os (NPO) [3][18] | Limits further bowel distension from swallowed air/fluid; reduces aspiration risk for anaesthesia | All patients, immediately |
| IV fluid resuscitation (Drip) [3][18] | Replaces intravascular volume lost through vomiting, third-space sequestration into dilated bowel, and reduced oral intake | Crystalloids (normal saline, Ringer's lactate, Hartmann's); guide by urine output, HR, BP. K⁺ replacement guided by serum levels (cautious in AKI) [3]. |
| Nasogastric tube decompression (Suck) [3][18] | Decompresses proximal bowel → reduces vomiting → reduces aspiration risk → reduces intraluminal pressure | NG tube (Ryle or Salem Sump) on free drainage + 4-hourly aspiration [3]. In neonates: OGT (orogastric tube) [8]. |
| IV antibiotics [2][3] | Bacterial translocation occurs through ischaemic, permeable bowel wall → prophylaxis against bacteraemia and peritonitis | Broad-spectrum covering bowel flora: typically IV ceftriaxone + metronidazole [13] or piperacillin-tazobactam. Mandatory for all patients undergoing surgery; warranted especially with complicated obstruction [3]. |
| Analgesia | Mesenteric stretch + ischaemia cause severe pain | Opioids are reasonable, though pain from mechanical IO often responds incompletely to analgesics [3]. |
| Urinary catheter | Monitor urine output as a guide to resuscitation adequacy | Target UO > 0.5 mL/kg/h (adults); > 1 mL/kg/h (neonates) |
| Monitoring | Detect deterioration early | Frequent monitor of vital signs, abdominal signs and X-rays [18] — serial abdominal examination, temperature, HR, BP, WCC, lactate, ABG |
Why Antibiotics for Everyone?
Even if the bowel looks viable on imaging, you cannot be sure until you see it directly (at endoscopy or surgery). Bacterial translocation begins early — as soon as the bowel wall becomes congested and oedematous, its mucosal barrier function is compromised. Giving antibiotics upfront provides a safety net against developing sepsis during the time between diagnosis and definitive treatment.
4. Indications for Emergency Surgery (All Types)
The lecture slides clearly delineate when conservative management must be abandoned and the patient taken straight to the operating theatre:
Indications for urgent surgery: Incarcerated, strangulated hernia; Suspected or proven strangulation; Peritonitis; Pneumoperitoneum; Pneumatosis cystoides intestinalis; Close loop obstruction; Volvulus with peritoneal signs [1]
Translating this to volvulus specifically:
| Indication | Why |
|---|---|
| Peritonitis (guarding, rigidity, rebound tenderness) | Indicates bowel perforation → faecal contamination of peritoneal cavity → endoscopic intervention is futile and dangerous (insufflation would worsen contamination) |
| Pneumoperitoneum (free gas under diaphragm) | Confirmed perforation — needs source control (resection of perforated bowel) |
| Pneumatosis cystoides intestinalis | Gas in bowel wall = transmural necrosis from bacterial invasion — the bowel is dead |
| Volvulus with peritoneal signs [1] | Combined mechanical + vascular compromise with peritoneal irritation — endoscopic decompression will not save gangrenous bowel |
| Failed endoscopic decompression | If the sigmoidoscope cannot reduce the volvulus, the twist is too tight or the bowel is too compromised → surgery is the only option [2][3] |
| Necrotic mucosa visualised at endoscopy | If sigmoidoscopy reveals dark, necrotic, or non-viable mucosa → procedure should be immediately stopped to prevent perforation → proceed to laparotomy [3] |
| Haemodynamic instability refractory to resuscitation | Suggests established sepsis from gangrenous bowel → source control urgently needed |
5. Management by Type
5.1 Sigmoid Volvulus
Sigmoid volvulus is the one type where non-operative management is the preferred first-line approach — specifically, endoscopic decompression. This is because the sigmoid is easily accessible with a sigmoidoscope, and successful decompression avoids an emergency operation in what is typically an elderly, comorbid patient.
Sigmoidoscopic decompression (recurrence: 50%). Surgery (perforation, strangulation or failed decompression). Resection. [1]
Sigmoid volvulus: conservative decompression preferred [2][18]
A. Non-Operative: Endoscopic Decompression (First Line)
| Step | Details | Rationale |
|---|---|---|
| Instrument | Flexible sigmoidoscopy [2] or rigid sigmoidoscopy [17] | The flexible scope can navigate the twist more easily; rigid scope is simpler and available at bedside |
| Technique | De-rotation with cautious insufflation [2] — gentle pressure advances the scope past the point of torsion, straightening and untwisting the sigmoid colon [3] | Minimal insufflation is critical — excessive air pressure in an already compromised bowel risks perforation |
| Signs of success | Sudden expulsion of gas and stool [2]; visualisation of a dilated proximal segment filled with gas and stool [3] | The decompressed segment releases its trapped contents when the twist is undone |
| Viability assessment | Allows assessment of viability of the colon — mucosa proximal to the site of obstruction should be inspected for evidence of bowel ischaemia [3] | Pink, healthy-looking mucosa = viable → proceed with rectal tube. Dark, necrotic mucosa = gangrenous → stop immediately and go to surgery [3]. |
| Post-decompression | Leave rectal tube in situ for 24 hours for decompression → serial AXR to monitor [2] | The rectal tube maintains the lumen open, prevents immediate re-torsion, and allows ongoing gas/stool drainage while the oedematous bowel recovers |
| Success rate | ~70–80% initial success | But recurrence rate is ~50% [1] — hence the need for definitive surgery in selected patients |
Lower gastrointestinal endoscopy — Diagnostic. Therapeutic: Decompression in sigmoid volvulus and pseudo-obstruction. Stenting. Cautions: to avoid excessive insufflation of gas [1]
Contraindications to endoscopic decompression:
- Peritonitis (guarding, rigidity, rebound tenderness) [1]
- Perforation (pneumoperitoneum on CXR/AXR)
- Necrotic mucosa seen during the procedure [3]
- Haemodynamic instability unresponsive to resuscitation
Why Not Just Keep Doing Endoscopic Decompression?
Because the recurrence rate is ~50% [1]. Each recurrence carries the same risk of ischaemia, gangrene, and perforation. Repeated endoscopic decompression without definitive surgery is like repeatedly draining an abscess without treating the source — eventually, you will lose the patient. This is why elective sigmoidectomy is recommended for appropriate candidates after successful initial decompression.
B. Operative Management — Emergency
Indicated when sigmoidoscopic reduction is unsuccessful, or in patients with signs and symptoms suggestive of peritonitis [3].
The choice of operation depends on bowel viability and patient fitness:
| Scenario | Operation | Explanation |
|---|---|---|
| Viable bowel, stable patient, no contamination | Sigmoid colectomy with primary anastomosis [3] | The redundant sigmoid is resected and the two healthy bowel ends are joined directly. Only safe when bowel ends are viable, no peritoneal contamination, and the patient is haemodynamically stable [3]. On-table colonic lavage may be performed to decompress and clean the unprepared proximal colon [2]. |
| Non-viable bowel, or contamination, or unstable patient | Emergency Hartmann's operation [2][18] — sigmoid resection + formation of end colostomy at LIF + closure of rectal stump | When the bowel is gangrenous or perforated, or the patient is too unstable for a prolonged operation with anastomosis, Hartmann's is the safer choice. A primary anastomosis in a contaminated, inflamed, or unprepared field has a very high leak rate. The colostomy can be reversed electively in 2–3 months [18]. |
| Alternative to Hartmann's | Paul-Mikulicz procedure — resection of volvulus + formation of double-barrel colostomy for future anastomosis [2] | Both ends of the bowel are brought out as adjacent stomas. This avoids leaving a closed rectal stump (which can leak/form abscess). Easier to reverse than Hartmann's. |
| Sigmoidopexy | Fixation of sigmoid colon to posterior abdominal wall | Rarely performed due to high risk of recurrence [3] — the underlying problem (redundant sigmoid) is not addressed |
C. Elective Sigmoidectomy — Definitive / Recurrence Prevention
Elective sigmoidectomy: for young patients or elderly with recurrent volvulus (not in every elderly: high mortality) due to high risk of recurrence after endoscopic Tx [2]
| Indication | Rationale |
|---|---|
| Young / fit patients after first episode | The recurrence rate after endoscopic decompression alone is ~50% [1]. Young patients have many decades ahead — the cumulative risk of recurrent volvulus with eventual gangrene is unacceptable. Elective surgery in a prepared, stable patient has much lower mortality than emergency surgery for a recurrence with gangrene. |
| Elderly patients with recurrent volvulus | If an elderly patient has had ≥ 2 episodes despite endoscopic treatment, the benefit of elective surgery outweighs the risk. However, elective sigmoidectomy is not offered to every elderly patient after first episode because the surgical mortality in this frail population is significant [2]. |
| Patients who cannot be reduced endoscopically but have no acute ischaemia | Semi-urgent sigmoidectomy after resuscitation |
The elective operation is typically a sigmoid colectomy with primary colorectal anastomosis (one-stage procedure). This can be done open or laparoscopically.
5.2 Caecal Volvulus
Caecal volvulus is fundamentally different from sigmoid volvulus in management because:
- Endoscopic reduction with colonoscopy is RARELY successful and therefore should NOT be attempted [3] — the colonoscope cannot reliably navigate the twist.
- Caecal volvulus is usually already ischaemic at presentation [2] — the thin-walled caecum distends rapidly (Laplace's law), and vascular compromise occurs early.
- Therefore, surgery is indicated as the primary treatment [2].
Caecal volvulus: surgery is indicated — usually ischaemic. Surgery: right hemicolectomy. Colonoscopic derotation ± caecopexy (fixation of caecum to RIF) — high recurrence [2]
The operative approach is guided by bowel viability and haemodynamic stability [3]:
| Bowel Compromise | Haemodynamic Stability | Treatment | Rationale |
|---|---|---|---|
| No | Stable | Surgical detorsion + Right hemicolectomy with primary ileocolic anastomosis [3] | Resection is required because detorsion alone is associated with a high failure rate — the underlying mobile caecum will simply twist again [3]. Right hemicolectomy removes the mobile caecum and ascending colon, eliminating the substrate for recurrence. |
| No | Unstable | Cecopexy + Cecostomy tube placement [3] | ONLY for patients who cannot tolerate a resectional procedure [3]. Cecopexy = fixation of caecum to RIF peritoneum to prevent re-torsion. Cecostomy tube = decompresses the caecum. However, recurrence is high because the fundamental problem (mobile caecum) is not fully addressed. |
| Yes | Stable | Right hemicolectomy with primary ileocolic anastomosis + defunctioning loop ileostomy [3] | Detorsion is NOT performed when the bowel is compromised because reperfusion of compromised bowel may promote bacteraemia and sepsis [3]. The gangrenous segment is resected en bloc. A defunctioning ileostomy protects the anastomosis. |
| Yes | Unstable | Right hemicolectomy with end ileostomy [3] | Quickest, safest option in a critically ill patient. No anastomosis (avoids leak risk). Ileostomy is reversed once the patient is stabilised [3]. |
Why NOT Detorse a Gangrenous Caecum?
It seems intuitive to untwist the bowel first to "save" it. But if the bowel is already gangrenous, untwisting it restores blood flow to dead, bacteria-laden tissue. This creates a reperfusion injury: reactive oxygen species flood the necrotic tissue, bacterial toxins and endotoxin wash out into the portal and systemic circulation, and the patient develops overwhelming sepsis. This is why detorsion is NOT performed when bowel is compromised [3] — you resect the dead bowel without untwisting it first.
5.3 Neonatal Midgut Volvulus (Malrotation)
This is a pure surgical emergency. There is no role for endoscopic management. The baby goes to theatre.
Management: Time is essence. Laparotomy. Malrotation — Ladd's procedure. Midgut volvulus: De-torting of volvulus, Assess viability, Resection if needed [4][6]
Pre-operative Preparation [3][8]
| Step | Details |
|---|---|
| NPO | Immediately on suspicion |
| NG/OGT decompression | Decompress stomach and proximal duodenum |
| IV access + bolus fluid | NS 10–20 mL/kg; correct electrolytes, glucose |
| Broad-spectrum IV antibiotics | Cover bowel flora (e.g., ampicillin + gentamicin + metronidazole) |
| Warming | Neonates lose heat rapidly — maintain normothermia |
| Bloods: electrolytes, glucose, CBC, blood gas, cross-match | Pre-operative workup |
The Ladd Procedure — Step by Step
The Ladd procedure (named after Dr William Ladd, 1880–1967, pioneer of paediatric surgery) is the definitive operation for malrotation ± midgut volvulus. Understanding its steps requires understanding what went wrong embryologically:
Untwist the bowel if volvulus (anticlockwise). Check viability ± resect ± anastomosis. Widen mesentery. Appendectomy. Return large bowel to left, small bowel to right (non-rotation position). [7]
| Step | Technique | Rationale |
|---|---|---|
| 1. Assessment for volvulus [3] | Inspect the mesentery for twisting; identify the direction of rotation | Must determine if volvulus is present before proceeding |
| 2. Detorsion | Volvulus is untwisted counterclockwise [3][7] | Midgut volvulus occurs clockwise (following the failed rotation); therefore, you reverse it by going anticlockwise |
| 3. Assess viability | Check viability ± resect ± anastomosis [7]. Inspect bowel colour, peristalsis, mesenteric arterial pulsation. Wrap in warm saline-soaked packs and reassess after 15–20 minutes if questionable. | Necrotic segments should be resected; segments with questionable viability should be preserved to avoid short bowel syndrome [3] — you only resect what is clearly dead. In a neonate, every centimetre of bowel matters. |
| 4. Ladd band division | Ladd bands are fibrous bands that run between duodenum and cecum → divide them completely [3] | These bands cross the duodenum and cause extrinsic compression. Dividing them relieves duodenal obstruction. |
| 5. Widen mesentery | Widen mesentery [7] — the narrow mesenteric base is broadened by dividing peritoneal attachments | A wider base reduces the risk of re-volvulus (harder for a wide fan to twist than a narrow pedicle) |
| 6. Appendectomy | Appendectomy [3][7] | The caecum is placed in the LUQ (non-rotation position) after the procedure. If the patient develops appendicitis in the future, it would present with LUQ pain, confusing the clinical picture. Removing the appendix pre-emptively eliminates this diagnostic trap. |
| 7. Position bowel in non-rotation | Return large bowel to left, small bowel to right (non-rotation position) [7] | The purpose of surgery is NOT to return the bowel to a normal configuration (which is anatomically impossible) [3], but to place it in a stable non-rotation position — small bowel on the right, colon on the left — with a widened mesenteric base. This creates adhesions that hold the bowel in place and makes future volvulus unlikely. |
Why Non-Rotation and Not 'Normal' Position?
Normal rotation requires 270° of anticlockwise rotation with subsequent fixation — you cannot recreate this surgically. Instead, the Ladd procedure places the bowel in the position of non-rotation (which is actually what the bowel looks like if it never rotated at all). The key is that the mesentery is widened and the bowel is positioned so it cannot twist. Adhesions that form post-operatively further stabilise the bowel.
If Extensive Bowel Necrosis Is Found
- If the entire midgut is gangrenous (catastrophic midgut volvulus), the surgeon faces an agonising decision: resecting the entire midgut leaves the child with short gut syndrome requiring lifelong TPN or intestinal transplantation.
- Resection if needed [4][6] — but the principle is maximal bowel preservation. A "second-look" laparotomy at 24–48 hours may be planned to reassess borderline segments before committing to resection.
6. Summary Table — Management by Type
| Type | First-Line | Indications for Surgery | Definitive Operation | Recurrence Prevention |
|---|---|---|---|---|
| Sigmoid volvulus | Flexible sigmoidoscopy decompression + rectal tube [1][2] | Failed endoscopy, peritonitis, perforation, necrotic mucosa at endoscopy, haemodynamic instability | Sigmoid colectomy ± primary anastomosis or Hartmann's [2][18] | Elective sigmoidectomy for young patients or recurrent volvulus [2] |
| Caecal volvulus | Surgery (endoscopy NOT recommended) [2][3] | All cases — surgery is primary treatment | Right hemicolectomy with primary ileocolic anastomosis (stable) or end ileostomy (unstable) [3] | Right hemicolectomy is definitive (removes mobile caecum) |
| Neonatal midgut volvulus | Emergency Ladd procedure [4][6][7] | All cases — this is a surgical emergency | Ladd procedure (detorsion, Ladd band division, widen mesentery, appendectomy, non-rotation positioning) ± bowel resection [3][7] | Ladd procedure itself prevents recurrence by widening mesentery + creating adhesions |
7. Assessing Bowel Viability at Surgery
A critical intra-operative decision is whether the bowel is viable or needs resection. The surgeon assesses [3]:
| Feature | Viable | Non-Viable |
|---|---|---|
| Colour | Dark colour becomes lighter (after detorsion/reperfusion) | Dark colour persists (does not pink up) |
| Mesenteric pulsation | Visible pulsation in mesenteric arteries | No detectable pulsation |
| Surface appearance | Shiny (serosal glistening intact) | Dull and lusterless (serosal necrosis) |
| Peristalsis | Peristalsis may be observed (give it time — wrap in warm packs for 10–15 min) | No peristalsis |
| Musculature | Firm (maintains tone) | Flaccid, paper-thin |
If viability is equivocal, the surgeon may use adjuncts:
- Intravenous fluorescein + Wood's lamp: fluorescein glows under UV light in perfused tissue; non-perfused tissue remains dark.
- Doppler ultrasound of mesenteric vessels.
- Second-look laparotomy at 24–48 hours (especially in neonates where preserving maximal bowel length is critical) [3].
8. Post-Operative Care and Monitoring
| Aspect | Details |
|---|---|
| NG/OGT decompression | Continue until bowel function returns (passage of flatus/stool) |
| IVF / TPN | Continue IV fluids; TPN if prolonged NPO anticipated (especially neonates) |
| Serial AXR | Monitor for resolution of dilatation; detect early re-volvulus or anastomotic leak |
| Stoma care (if applicable) | Education on colostomy/ileostomy management; plan for reversal (typically 2–3 months post-op for Hartmann's) |
| Signs of resolution [18] | Passage of flatus/stool, decreased abdominal distension, reduced NG tube output, resolved AXR signs |
High Yield Summary — Management of Volvulus
All volvulus: Resuscitate first — NPO, IVF, NG tube, IV antibiotics, monitoring.
Sigmoid volvulus:
- First line: Flexible sigmoidoscopy decompression with cautious insufflation → rectal tube in situ 24h → serial AXR.
- Recurrence ~50% → elective sigmoidectomy for young patients or recurrent episodes.
- Surgery if: failed endoscopy, peritonitis, perforation, necrotic mucosa at endoscopy.
- Operations: Sigmoid colectomy + primary anastomosis (viable, stable) or Hartmann's (non-viable/unstable/contaminated) or Paul-Mikulicz (double-barrel colostomy).
Caecal volvulus:
- Endoscopy NOT recommended — surgery is the primary treatment.
- Right hemicolectomy is definitive.
- Match operation to patient stability: primary anastomosis (stable) vs end ileostomy (unstable).
- Do NOT detorse gangrenous bowel — reperfusion injury causes sepsis.
Neonatal midgut volvulus:
- Emergency Ladd procedure: Untwist anticlockwise → assess viability ± resect → divide Ladd bands → widen mesentery → appendectomy → non-rotation position.
- Time is essence — delay = short gut syndrome.
Indications for emergency laparotomy: Peritonitis, pneumoperitoneum, pneumatosis, volvulus with peritoneal signs, failed endoscopic decompression, necrotic mucosa at endoscopy.
Active Recall - Management of Volvulus
1. What is the first-line treatment for sigmoid volvulus without signs of ischaemia, and what indicates successful decompression?
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First line: flexible sigmoidoscopy decompression with cautious insufflation. Success indicated by sudden expulsion of gas and stool. Post-procedure: leave rectal tube in situ for 24h for ongoing decompression, serial AXR monitoring.
2. Why is elective sigmoidectomy recommended after successful endoscopic decompression of sigmoid volvulus in young patients?
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Because recurrence rate after endoscopic decompression alone is approximately 50%. Young patients have many decades of cumulative recurrence risk. Each recurrence risks ischaemia, gangrene, and perforation. Elective surgery in a prepared stable patient has much lower mortality than emergency surgery for gangrenous recurrence.
3. Name the five steps of the Ladd procedure for neonatal malrotation with midgut volvulus.
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(1) Untwist volvulus anticlockwise and assess viability, resect necrotic segments if needed. (2) Divide Ladd bands between duodenum and caecum. (3) Widen the mesenteric base. (4) Appendectomy. (5) Return bowel to non-rotation position — large bowel to left, small bowel to right.
4. A patient with caecal volvulus has gangrenous bowel and is haemodynamically unstable. What operation should be performed and why is detorsion avoided?
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Right hemicolectomy with end ileostomy (no anastomosis in unstable patient). Detorsion is avoided because reperfusion of compromised/gangrenous bowel washes bacterial toxins and endotoxin into the systemic circulation, promoting bacteraemia and septic shock. The dead bowel is resected en bloc without untwisting.
5. List four indications for emergency laparotomy in volvulus as mentioned in the lecture slides.
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Any 4 of: (1) Peritonitis, (2) Pneumoperitoneum, (3) Pneumatosis cystoides intestinalis, (4) Volvulus with peritoneal signs, (5) Failed endoscopic decompression, (6) Suspected or proven strangulation, (7) Incarcerated strangulated hernia, (8) Close-loop obstruction.
6. What is a Hartmann's operation and when is it indicated in sigmoid volvulus?
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Hartmann's operation: sigmoid resection + formation of temporary end colostomy at LIF + closure of rectal stump. Re-anastomosis performed electively 2-3 months later. Indicated when sigmoid is gangrenous/perforated, there is faecal contamination of peritoneal cavity, or the patient is haemodynamically unstable — situations where primary anastomosis has unacceptably high leak rate.
References
[1] Lecture slides: GC 194. Intestinal obstruction colorectal cancer.pdf (p25, p44, p62) [2] Senior notes: maxim.md (Section: Volvulus, Hartmann's operation) [3] Senior notes: felixlai.md (Sections: Volvulus — Treatment, Intestinal obstruction — Treatment, Intestinal malrotation — Treatment) [4] Lecture slides: GC 205. The newborn baby is vomiting repeatedly Neonatal intestinal obstruction and other GI emergencies.pdf (p25) [6] Lecture slides: Neonatal Surgery.pdf (p33) [7] Lecture slides: Case Study – Paediatric Surgery Bilious vomiting of new-born _ACH Fung.pdf (p34) [8] Senior notes: maxim.md (Section: Malrotation & volvulus table — Management) [13] Senior notes: maxim.md (Section: Intestinal obstruction — Initial management) [17] Senior notes: maxim.md (Section: Rigid sigmoidoscopy — Therapeutic indication) [18] Lecture slides: GC 194. Intestinal obstruction colorectal cancer.pdf (p7, p28, p43)
Complications of Volvulus
Complications of volvulus can be organised into three temporal categories: (1) complications of the volvulus itself (i.e., what happens if it is not treated or treatment is delayed), (2) complications of treatment (endoscopic and surgical), and (3) long-term sequelae. Each complication flows logically from the underlying pathophysiology — the twist, the ischaemia, the surgery, or the recovery.
1. Complications of Volvulus Itself (Pre-Treatment / Delayed Treatment)
These complications arise from the fundamental pathophysiology of volvulus: closed-loop obstruction + mesenteric vascular occlusion. They follow a predictable cascade of escalating severity.
1.1 Strangulation (Bowel Ischaemia → Necrosis)
Blood supply is compromised when bowel dilation is excessive. Bowel becomes ischaemic and leads to necrosis or perforation. [3]
| Feature | Explanation |
|---|---|
| Mechanism | The twisted mesentery compresses veins first (low pressure), then arteries. Continued arterial inflow with obstructed venous outflow causes venous congestion → bowel wall oedema → haemorrhagic infarction → transmural necrosis. Additionally, increased intraluminal pressure within the closed loop directly compresses mural vessels, and the interrupted mesenteric blood flow from the twist compounds the insult [3]. |
| Why volvulus is particularly dangerous | Because it is a closed-loop obstruction, the trapped segment cannot decompress. Intraluminal pressure rises far more rapidly than in simple obstruction, accelerating the vascular compromise. |
| Causes of strangulation | ↑ Intraluminal pressure; Direct pressure on bowel wall; Interrupted mesenteric blood flow [3] |
| Features suggestive of strangulation | Clinical (Signs): Fever, Tachycardia, Peritoneal signs (guarding, rigidity, rebound). Clinical (Symptoms): Continuous or worsening abdominal pain (colicky pain becomes constant as ischaemia sets in). Biochemical: Leukocytosis, Metabolic acidosis (lactic). Radiological: Pneumoperitoneum, Pneumatosis intestinalis, Portal venous gas [3]. |
| Prognosis | Morbidity and mortality are dependent on duration of ischaemia and its extent. Any length of ischaemic bowel can cause significant systemic effects secondary to sepsis and dehydration [3]. |
Strangulation — The Core Complication
Strangulation is not a separate diagnosis from volvulus — it is the inevitable consequence of untreated volvulus. Every volvulus will progress to strangulation if the twist is not relieved. The clinical question is always: "Has this volvulus already strangulated?" If the answer is yes, the patient goes to theatre immediately. If the answer is not yet, you have a window for endoscopic decompression (sigmoid) or planned surgery (caecal).
1.2 Bowel Perforation → Peritonitis
| Feature | Explanation |
|---|---|
| Mechanism | Transmural necrosis weakens the bowel wall → the ischaemic, gangrenous wall ruptures under the rising intraluminal pressure → luminal contents (faeces, gas, bacteria) spill into the peritoneal cavity → faecal peritonitis. |
| Why this is catastrophic | Faecal peritonitis carries a mortality of 30–50% in elderly patients. The peritoneal cavity is flooded with enteric bacteria (E. coli, Bacteroides, Enterococcus) and bacterial endotoxin → massive systemic inflammatory response → septic shock → multi-organ failure. |
| Clinical features | Sudden worsening of abdominal pain → board-like rigidity of the abdomen; signs of septic shock (hypotension, tachycardia, fever or hypothermia, altered consciousness). Peritonitis from intestinal perforation due to volvulus [3]. |
| Radiological signs | Pneumoperitoneum (free gas under diaphragm on erect CXR/AXR); Rigler sign (double-wall sign — both sides of the bowel wall outlined by gas) [3]. |
1.3 Sepsis and Septic Shock
| Feature | Explanation |
|---|---|
| Mechanism | Even before frank perforation, bacterial translocation occurs through the ischaemic, permeable bowel wall → bacteria and endotoxin enter the mesenteric venous system → portal circulation → systemic bacteraemia. Once perforation occurs, the bacterial load multiplies enormously. |
| Clinical features | Shock (Haemodynamic instability) — Septic shock due to bowel necrosis [3]. SIRS criteria → sepsis → septic shock (hypotension refractory to fluid resuscitation, requiring vasopressors). |
| Multi-organ failure | Septic shock triggers a cascade: acute kidney injury (renal hypoperfusion), ARDS (pulmonary capillary leak), DIC (consumptive coagulopathy), hepatic failure → death. |
1.4 Dehydration, Hypovolaemia, and Electrolyte Disturbance
Complications — Systemic: dehydration, electrolyte disturbance, aspiration pneumonia [13]
| Complication | Mechanism |
|---|---|
| Dehydration / hypovolaemia | Reduced oral intake + vomiting + third-space fluid sequestration into dilated bowel lumen and peritoneal cavity → intravascular volume depletion → pre-renal AKI, haemodynamic instability. Hypovolaemia due to dehydration or third-space loss [3]. |
| Hypokalaemia | Direct K⁺ loss in vomitus + metabolic alkalosis driving K⁺ intracellularly + RAAS activation → renal K⁺ wasting. Dangerous because hypokalaemia causes cardiac arrhythmias and paralytic ileus (worsening the obstruction). |
| Hyponatraemia | Na⁺ loss in vomitus + third-space losses. |
| Metabolic alkalosis | Loss of gastric HCl from vomiting → net gain of HCO₃⁻. |
| Metabolic acidosis (lactic) | Bowel ischaemia → anaerobic glycolysis → lactate accumulation; hypovolaemia → systemic hypoperfusion. May co-exist with alkalosis (mixed picture). |
1.5 Aspiration Pneumonia
| Feature | Explanation |
|---|---|
| Mechanism | Massive proximal bowel distension → retrograde flow of intestinal contents into the stomach → vomiting of large volumes of faeculent or bilious fluid → aspiration into the tracheobronchial tree. Particularly dangerous in obtunded patients (elderly, neuropsychiatric patients, sedated patients). |
| Clinical features | Fever, cough, tachypnoea, hypoxia, crackles on auscultation. CXR shows infiltrates (typically right lower lobe due to anatomy of right main bronchus). |
| Prevention | NG tube decompression (drip and suck) is a key early intervention — by keeping the stomach empty, you dramatically reduce aspiration risk [3]. |
1.6 Recurrence
| Feature | Explanation |
|---|---|
| Sigmoid volvulus | Recurrence after endoscopic decompression is approximately 50% [1]. The underlying problem (redundant sigmoid with narrow mesenteric attachment) is not corrected by decompression alone. Each recurrence carries the full risk of ischaemia and gangrene. |
| Caecal volvulus | Colonoscopic derotation ± caecopexy has high recurrence [2]. This is why right hemicolectomy (which removes the mobile caecum entirely) is the definitive treatment. |
| Prevention | Elective sigmoidectomy for sigmoid volvulus; right hemicolectomy for caecal volvulus. |
2. Complications of Treatment
2.1 Complications of Endoscopic Decompression (Sigmoidoscopy)
| Complication | Mechanism | Management |
|---|---|---|
| Bowel perforation during procedure | Excessive insufflation of gas into an already compromised, thinned bowel wall → perforation. This is why the procedure requires cautious insufflation [2]. Also, advancing the scope through necrotic mucosa can tear the bowel wall. | Immediate emergency laparotomy for source control |
| Failed reduction | The twist is too tight, or extensive oedema prevents the scope from passing the torsion point. Occurs in ~20–30% of attempts. | Proceed to emergency surgery |
| Incomplete assessment of viability | Endoscopy can only visualise the luminal mucosa — it cannot assess the serosal surface or mesentery. Mucosa may appear deceptively viable while the outer wall is gangrenous. | Maintain high index of suspicion; monitor closely post-decompression with serial AXR, lactate, clinical exam. Any deterioration → laparotomy. |
| Recurrence (see above) | The decompression treats the acute event but not the underlying anatomical predisposition. | Elective sigmoidectomy in appropriate candidates |
2.2 Complications of Surgery (General Post-Operative)
| Complication | Mechanism | Relevance to Volvulus |
|---|---|---|
| Anastomotic leak | The join between the two bowel ends fails to heal → faecal contents leak into the peritoneal cavity → peritonitis, sepsis. Risk factors include: emergency surgery, unprepared bowel, poor blood supply to anastomotic ends, patient malnutrition, steroid use, haemodynamic instability. | Particularly relevant when primary anastomosis is performed in the emergency setting for volvulus. This is why Hartmann's procedure (no anastomosis) is preferred in unstable or contaminated settings [2]. |
| Wound infection / Surgical site infection | Contamination of the wound with faecal/enteric organisms during emergency surgery on unprepared bowel. | Higher risk in emergency volvulus surgery than elective surgery due to faecal contamination |
| Post-operative ileus | Any abdominal surgery temporarily disrupts bowel motility. The myenteric plexus is inhibited by surgical handling, inflammation, and opioid analgesia. | Monitor for return of bowel function (passage of flatus/stool). |
| Intra-abdominal abscess | Collection of infected fluid in the peritoneal cavity post-operatively, especially if there was faecal contamination or an anastomotic leak. | Presents as persistent fever, raised WCC, failure to progress. Diagnosed by CT; managed by percutaneous drainage + antibiotics. |
| Adhesive small bowel obstruction | Any abdominal surgery creates adhesions (fibrous bands between organs/peritoneum). These can cause future bowel obstruction. Small bowel obstruction from adhesions is listed as a complication of the Ladd procedure [3]. | A known long-term risk of any intra-abdominal surgery. Risk is higher after emergency surgery with contamination/inflammation. |
2.3 Complications Specific to Hartmann's Procedure
Specific complications: Rectal stump leak, abscess, fistula; Ureter injury; Stoma complications [2]
| Complication | Mechanism |
|---|---|
| Rectal stump leak / abscess / fistula | The closed rectal stump can break down, especially in the setting of inflammation and poor tissue quality, leading to pelvic abscess or fistula formation. |
| Ureteric injury | The left ureter runs in close proximity to the sigmoid mesocolon. During emergency surgery with inflamed, distorted anatomy, the ureter can be inadvertently divided, ligated, or cauterised. |
| Stoma complications | Includes: parastomal hernia (weakness in abdominal wall around stoma), stoma prolapse (bowel protrudes excessively), stoma retraction (stoma sinks below skin level), skin excoriation (irritant output damages peristomal skin), stoma stenosis (narrowing of the stoma opening), high-output stoma (especially ileostomy → dehydration and electrolyte losses). |
| Non-reversal of stoma | Up to 30–40% of Hartmann's procedures are never reversed, particularly in elderly, frail patients. The patient lives permanently with a colostomy. |
2.4 Complications Specific to the Ladd Procedure (Neonatal)
| Complication | Mechanism | Clinical Significance |
|---|---|---|
| Small bowel obstruction from adhesions [3] | Adhesions are inevitable after any laparotomy; in neonates, the relatively small abdominal cavity increases the chance that adhesive bands will kink a small bowel loop. | Recurrent vomiting, abdominal distension in a child with a history of Ladd procedure → suspect adhesive SBO |
| Short bowel syndrome (if resection is necessary when necrotic bowel is present) [3][7] | If midgut volvulus causes extensive necrosis requiring massive small bowel resection, the child is left with insufficient absorptive surface. | Defined by functional malabsorption of macronutrients and micronutrients. |
| Recurrent volvulus post-Ladd procedure | Rare (~2–5%) but possible, particularly after laparoscopic Ladd procedure (fewer adhesions form → less fixation of bowel in non-rotation position). | Presents with bilious vomiting again → urgent re-evaluation |
3. Short Bowel Syndrome — The Most Devastating Long-Term Complication of Midgut Volvulus
This deserves special attention because it is the single most feared consequence of neonatal midgut volvulus and is explicitly highlighted in the lecture slides.
Complications of extensive small bowel resection — short bowel syndrome: Malabsorption; TPN-related cholestasis, liver failure; Central line sepsis; Long-term quality of life? Most are premature infants — complications of prematurity [7]
3.1 What Is Short Bowel Syndrome?
Short bowel syndrome (SBS) is a state of functional intestinal insufficiency following massive bowel resection, where the remaining intestine cannot absorb sufficient nutrients, fluids, and electrolytes to maintain health without supplementation. In children, the most common cause is midgut volvulus [3].
3.2 Complications of SBS (and Its Treatment)
| Complication | Mechanism | Why |
|---|---|---|
| Malabsorption [7] | Reduced absorptive surface area → insufficient digestion and absorption of macronutrients (carbohydrates, fats, proteins) and micronutrients (vitamins, minerals, trace elements) | The small bowel is where the vast majority of nutrient absorption occurs. Loss of jejunum → carbohydrate/protein malabsorption. Loss of ileum → bile salt and B₁₂ malabsorption (the ileum is the only site for bile salt reabsorption and B₁₂ absorption). |
| TPN-related cholestasis → liver failure [7] | Patients with SBS require long-term total parenteral nutrition (TPN). TPN bypasses the gut, reducing enteral stimulation of bile flow → cholestasis (bile stagnation in liver) → progressive liver fibrosis → cirrhosis → liver failure. TPN components (lipid emulsions, glucose) may also be directly hepatotoxic. | This is the leading cause of death in children with SBS on long-term TPN. "Intestinal failure-associated liver disease" (IFALD). |
| Central line sepsis [7] | TPN is delivered through a central venous catheter (e.g., Hickman line, PICC). Long-term central venous access carries a continuous risk of catheter-related bloodstream infections (CRBSI) from skin flora (Staph epidermidis, Staph aureus) or gut organisms. | Each episode of line sepsis risks metastatic infection (endocarditis, osteomyelitis) and loss of venous access sites. Eventually, patients "run out of veins." |
| Long-term quality of life [7] | Life tethered to IV infusions (TPN typically 12–18 hours/day); recurrent hospitalisations for sepsis, dehydration, metabolic crises; growth and developmental delay in children; psychological impact. | A devastating chronic condition that affects every aspect of life. |
| Complications of prematurity [7] | Most are premature infants — they carry the additional burden of prematurity-related complications (retinopathy of prematurity, bronchopulmonary dysplasia, intraventricular haemorrhage, developmental delay). | The neonatal midgut volvulus patient often starts life at a significant disadvantage. |
| D-lactic acidosis | Unabsorbed carbohydrates reach the colon → bacterial fermentation produces D-lactate → systemic absorption → encephalopathy (confusion, ataxia, slurred speech). | Unusual metabolic complication of SBS with intact colon. Standard lactate assays measure L-lactate; must specifically request D-lactate. |
| Oxalate kidney stones | Unabsorbed fatty acids bind calcium in the gut lumen → reduced calcium available to bind oxalate → free oxalate is absorbed from the colon → hyperoxaluria → calcium oxalate renal stones. | Occurs specifically when the colon is in continuity (provides the absorptive surface for free oxalate). |
Why Is Prevention of Short Bowel Syndrome So Critical in Neonatal Surgery?
Once the midgut is gangrenous and resected, you cannot get it back. There is no artificial replacement for the small bowel that matches its absorptive capacity. Intestinal transplantation exists but carries enormous risks (rejection, infection, graft-versus-host disease) and limited availability. This is why the neonatal surgical mantra is "time is essence" [4][6] — early surgery before gangrene sets in preserves bowel and prevents SBS. And even when gangrene is found, segments with questionable viability should be preserved [3] — resect only what is clearly dead, consider second-look laparotomy.
4. Summary Table — Complications at a Glance
| Category | Complication | Mechanism | Key Point |
|---|---|---|---|
| Pre-treatment | Strangulation → Necrosis | Closed-loop + vascular compromise | Duration and extent of ischaemia determine outcome [3] |
| Perforation → Peritonitis | Necrotic wall ruptures under pressure | Pneumoperitoneum on CXR = straight to OT | |
| Sepsis → Septic shock → MOF | Bacterial translocation ± perforation | Any length of ischaemic bowel can cause significant systemic effects [3] | |
| Dehydration + electrolyte disturbance | Vomiting, third-spacing, reduced intake | Hypokalaemia, hyponatraemia, metabolic alkalosis/acidosis | |
| Aspiration pneumonia | Vomiting + obtunded patient | Prevented by NG tube decompression [13] | |
| Recurrence | Underlying anatomy not corrected | ~50% after endoscopic decompression of sigmoid [1] | |
| Post-endoscopy | Perforation during procedure | Excessive insufflation or scope trauma | Use cautious insufflation [2] |
| Post-surgery | Anastomotic leak | Poor healing at join site | Higher risk in emergency, contaminated settings |
| Wound infection | Faecal contamination | Higher in emergency surgery | |
| Adhesive SBO | Post-operative adhesion formation | Long-term risk after any abdominal surgery [3] | |
| Rectal stump leak / ureteric injury | Hartmann's-specific | Anatomical proximity of ureter to sigmoid [2] | |
| Stoma complications | Colostomy / ileostomy-related | Parastomal hernia, prolapse, retraction, skin excoriation [2] | |
| Long-term (neonatal) | Short bowel syndrome | Massive resection for gangrenous midgut | Malabsorption, TPN cholestasis → liver failure, central line sepsis [7] |
High Yield Summary — Complications of Volvulus
Complications of volvulus itself (the natural history of untreated volvulus):
- Strangulation → ischaemia → necrosis → perforation → faecal peritonitis → septic shock → multi-organ failure → death.
- Dehydration and electrolyte disturbance (hypokalaemia, hyponatraemia, metabolic alkalosis ± acidosis).
- Aspiration pneumonia (prevented by NG tube).
- Recurrence: ~50% after endoscopic decompression of sigmoid volvulus.
Features of strangulation: Fever, tachycardia, peritoneal signs; continuous pain; leukocytosis, metabolic acidosis; pneumoperitoneum, pneumatosis intestinalis, portal venous gas.
Complications of treatment:
- Endoscopic: perforation, failed reduction, recurrence.
- Surgical: anastomotic leak, wound infection, post-op ileus, intra-abdominal abscess, adhesive SBO.
- Hartmann's-specific: rectal stump leak, ureteric injury, stoma complications.
- Ladd procedure-specific: adhesive SBO, recurrent volvulus, short bowel syndrome.
Short bowel syndrome (the most devastating long-term complication of neonatal midgut volvulus):
- Malabsorption, TPN-related cholestasis → liver failure, central line sepsis, long-term quality of life concerns.
- Prevention: early surgery (time is essence), maximal bowel preservation.
Active Recall - Complications of Volvulus
1. List the three pathophysiological causes of strangulation in intestinal obstruction/volvulus.
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(1) Increased intraluminal pressure; (2) Direct pressure on bowel wall; (3) Interrupted mesenteric blood flow. These cause sequential venous congestion then arterial compromise, leading to ischaemia, necrosis, and perforation.
2. What are the clinical, biochemical, and radiological features suggestive of strangulated bowel in volvulus?
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Clinical signs: fever, tachycardia, peritoneal signs. Clinical symptoms: continuous or worsening abdominal pain. Biochemical: leukocytosis, metabolic acidosis (raised lactate). Radiological: pneumoperitoneum, pneumatosis intestinalis, portal venous gas.
3. Why is the recurrence rate of sigmoid volvulus approximately 50% after endoscopic decompression alone?
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Endoscopic decompression treats the acute twist but does not correct the underlying anatomical predisposition — the redundant elongated sigmoid colon with narrow mesenteric attachment. The same anatomy that caused the first volvulus remains, allowing the sigmoid to twist again.
4. Name four complications of short bowel syndrome following neonatal midgut volvulus requiring extensive bowel resection.
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Any 4 of: (1) Malabsorption of macronutrients and micronutrients; (2) TPN-related cholestasis progressing to liver failure; (3) Central line sepsis; (4) D-lactic acidosis; (5) Oxalate renal stones; (6) Poor long-term quality of life; (7) Growth and developmental delay. Plus complications of prematurity if applicable.
5. What are the specific complications of Hartmann's procedure performed for gangrenous sigmoid volvulus?
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Rectal stump leak, abscess, or fistula; ureteric injury (left ureter runs close to sigmoid mesocolon); stoma complications (parastomal hernia, prolapse, retraction, skin excoriation, stenosis); non-reversal of stoma (up to 30-40% never reversed, especially in elderly).
6. Why should detorsion NOT be performed on gangrenous bowel in caecal volvulus before resection?
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Detorsion of gangrenous bowel restores blood flow to necrotic, bacteria-laden tissue, causing reperfusion injury: reactive oxygen species damage tissue, and bacterial toxins and endotoxin are washed into the portal and systemic circulation, promoting bacteraemia and septic shock. The gangrenous segment should be resected en bloc without untwisting.
References
[1] Lecture slides: GC 194. Intestinal obstruction colorectal cancer.pdf (p62) [2] Senior notes: maxim.md (Sections: Volvulus, Hartmann's operation) [3] Senior notes: felixlai.md (Sections: Volvulus, Intestinal obstruction — Complications, Intestinal malrotation — Complications, Strangulation) [4] Lecture slides: GC 205. The newborn baby is vomiting repeatedly Neonatal intestinal obstruction and other GI emergencies.pdf (p25) [6] Lecture slides: Neonatal Surgery.pdf (p33) [7] Lecture slides: Case Study – Paediatric Surgery Bilious vomiting of new-born _ACH Fung.pdf (p22) [13] Senior notes: maxim.md (Section: Intestinal obstruction — Complications)