Intussusception
Intussusception is the telescoping of one segment of bowel into an adjacent distal segment, most commonly occurring in infants aged 6 to 36 months, leading to intestinal obstruction and potential ischemia.
Intussusception in Children
Intussusception — from the Latin intus ("within") + susceptio ("to take up/receive") — refers to the invagination (telescoping) of a proximal segment of bowel (the intussusceptum) into an immediately distal segment (the intussuscipiens) [1][2][3]. Think of it like pushing a telescope inward: one part of the bowel slides into the next, dragging its mesentery and blood supply along with it.
It is the most common cause of intestinal obstruction in infants aged 6–36 months and represents the most common abdominal emergency in early childhood [1][2][3].
Terminology Breakdown
- Intussusceptum = the proximal segment that "enters" (the inner tube — this is the part that undergoes ischaemia first because its mesentery gets compressed)
- Intussuscipiens = the distal receiving segment (the outer tube)
- The mesentery of the intussusceptum is dragged between the two layers → compressed → venous then arterial compromise
| Feature | Detail |
|---|---|
| Incidence | ~1–4 per 1,000 live births; most common abdominal emergency in early childhood [1][2] |
| Peak age | 6–36 months (majority < 2 years); rare before 3 months and after 6 years [1][2] |
| Sex | Male predominance (M:F ≈ 3:2) [2] |
| Seasonality | Slight peaks in spring and autumn — paralleling viral gastroenteritis and URTI seasons |
| Geography | Worldwide; no strong ethnic predilection. In Hong Kong, rotavirus and adenovirus remain common triggers in the pre-vaccine era; post-rotavirus-vaccine surveillance shows a very small incremental risk (see below) |
High Yield: When intussusception occurs outside the typical 6–36 month age window (especially > 6 years), strongly suspect a pathological lead point [1][2][3].
Rotavirus Vaccine Association
- First-generation rotavirus vaccine (RotaShield) was withdrawn in 1999 due to a 1 in 10,000 risk of intussusception.
- Current vaccines (RotaTeq, Rotarix) carry a very small increased risk (~1–5 per 100,000), primarily within the first week after the first dose [3].
- This is why rotavirus vaccine should ideally be given starting at 6 weeks of age with the first dose no later than 14 weeks 6 days — to minimise overlap with peak intussusception age.
- In Hong Kong, rotavirus vaccine is available but is NOT part of the routine government Childhood Immunisation Programme (it is self-financed).
Anatomy and Function
To understand intussusception you need to appreciate the anatomy of the ileocaecal region:
-
Terminal ileum — the last ~20 cm of the small bowel; this is where Peyer's patches (organised lymphoid follicles in the submucosa) are most concentrated. In infants, Peyer's patches are large and reactive because the infant immune system is encountering many antigens for the first time.
-
Ileocaecal valve (ICV) — a physiological sphincter where the ileum opens into the caecum. This is a natural "funnel point" — the narrowing at the ICV acts as a pivot point that allows a swollen terminal ileal segment to be "caught" by peristalsis and pushed through.
-
Caecum and ascending colon — the receiving segment. In infants the caecum is relatively mobile (not yet fully fixed to the retroperitoneum), which may facilitate telescoping.
-
Mesentery — the fan-shaped peritoneal fold carrying blood vessels, lymphatics, and nerves to the bowel. When the intussusceptum telescopes in, it drags its mesentery with it → the vessels get compressed between the two walls → venous congestion → oedema → arterial compromise → ischaemia → necrosis → perforation.
- Prominent Peyer's patches in the terminal ileum that enlarge further with viral infections → act as a "lead point."
- Relatively mobile caecum in young children.
- High peristaltic activity in the growing gut.
- The ileocaecal valve acts as a fulcrum — the most common intussusception type is therefore ileocolic (ileocaecal) [1][2][3].
Aetiology and Pathophysiology
A. Aetiology
- No clear disease trigger or pathological lead point [2].
- Proposed mechanism: reactive lymphoid hyperplasia (hypertrophy of Peyer's patches) in the lymphoid-rich terminal ileum secondary to:
- Viral upper respiratory tract infection (URTI) — adenovirus (serotypes 1, 2, 5), HHV-6
- Viral gastroenteritis — rotavirus, norovirus, enteric adenovirus (serotype 40/41)
- Other viral infections — EBV, CMV
- The enlarged Peyer's patch protrudes into the lumen → gets "grabbed" by normal peristalsis → dragged distally → initiates telescoping [1][2].
- Seasonal variation supports a viral trigger (peaks in spring/autumn).
- Many children have a preceding history of URTI or gastroenteritis in the days before presentation [1][3].
Why Peyer's patches?
Peyer's patches are submucosal aggregates of lymphoid tissue concentrated in the terminal ileum. In young children, they are disproportionately large relative to the bowel wall. When stimulated by a viral infection, they undergo hyperplasia — swelling into the lumen like small polyps. The vigorous peristalsis of a young child's bowel then catches these swollen patches and telescopes them forward through the ileocaecal valve.
A "lead point" is a structural lesion in the bowel wall that is trapped by peristalsis and pulled into the distal segment. The likelihood of a pathological lead point increases with age — if a child > 3 years (and especially > 6 years) presents with intussusception, actively search for one.
| Lead Point | Key Features |
|---|---|
| Meckel's diverticulum | Most common pathological lead point overall; a true diverticulum of the terminal ileum (remnant of omphalomesenteric duct); "rule of twos" — 2% of population, 2 feet from ICV, 2 inches long; should be considered in recurrent small bowel intussusception [4][5] |
| Polyps | Juvenile polyps, Peutz-Jeghers polyps (hamartomatous), familial adenomatous polyposis |
| Lymphoma | Particularly Burkitt lymphoma (B-cell, EBV-associated) — ileocaecal region is a classic site; consider in older children with intussusception [1][2] |
| Duplication cysts | Congenital enteric duplication; fluid-filled cyst sharing a muscular wall with the adjacent bowel |
| Henoch-Schönlein purpura (HSP) / IgA vasculitis | Submucosal haemorrhage/oedema of the bowel wall acts as a lead point; typically causes ileo-ileal intussusception [2] |
| Cystic fibrosis | Inspissated meconium / thick intestinal secretions |
| Rotavirus vaccine | Small risk, especially within 1 week of first dose [3] |
| Post-operative | Uncoordinated peristaltic activity; traction from sutures or devices (e.g. gastrojejunal feeding tube) [2] |
| Others | Haemangioma, lipoma, foreign body, parasitic worms (Ascaris), appendiceal stump |
Exam Pearl
A common exam mistake is to assume all paediatric intussusception is idiopathic. Remember:
- Recurrent intussusception → think pathological lead point (especially Meckel's diverticulum)
- Child > 3–6 years → think pathological lead point (lymphoma, polyp, Meckel's)
- Ileo-ileal pattern → think HSP, post-operative, or Meckel's
- Adults → ALWAYS assume a pathological lead point (tumour until proven otherwise) [3]
| Type | Segment | Proportion | Notes |
|---|---|---|---|
| Ileocolic (ileocaecal) | Terminal ileum → through ICV into colon | ~85–90% | Most common in children |
| Ileo-ileal | Small bowel → small bowel | ~5–10% | More common in HSP, post-op, neonates; less likely to respond to non-operative reduction; more likely to resolve spontaneously [2] |
| Colocolic | Colon → colon | Rare in children | More common in adults (think colonic tumour) |
| Jejuno-jejunal / Jejuno-ileal | Small bowel variants | Rare | Usually pathological lead point |
Understanding the pathophysiology is crucial because every clinical feature can be traced back to this sequence:
Detailed stepwise explanation:
-
Initiation — A "lead point" (hypertrophied Peyer's patch or structural lesion) protrudes into the bowel lumen. Normal peristalsis grabs it and propels it distally.
-
Telescoping — The proximal bowel segment (intussusceptum) progressively invaginates into the distal segment (intussuscipiens). The mesentery is dragged in between the two layers.
-
Venous obstruction (early) — Mesenteric veins are thin-walled and low-pressure, so they are compressed first → venous congestion → engorgement of the trapped bowel wall → mucosal oedema.
-
Mucosal ooze — Congested, oedematous mucosa weeps blood and mucus into the lumen → this produces the classic "red currant jelly stool" (a late sign, appearing ~12–24 hours after onset) [1][2][3].
-
Arterial compromise (later) — As oedema worsens, the thicker-walled arteries are also compressed → transmural ischaemia → gangrenous bowel.
-
Mechanical obstruction — The intussusception physically obstructs the bowel lumen:
- Proximal bowel dilates → colicky abdominal pain (due to powerful peristaltic contractions trying to overcome the obstruction)
- Bilious vomiting occurs because the obstruction is usually distal to the ampulla of Vater [3]
- Abdominal distension develops as the obstruction progresses
-
Necrosis and perforation — If untreated → gangrenous bowel → perforation → faecal peritonitis → sepsis → shock → death.
The natural history is progressive. Early presentation = high success with non-operative reduction. Late presentation = higher risk of perforation and need for surgery. This is why time to diagnosis matters enormously.
Classification
By Location (see table above)
- Idiopathic (vast majority in children)
- Secondary (pathological lead point)
- Post-operative
- Reducible (amenable to pneumatic/hydrostatic reduction)
- Irreducible (failed reduction, peritonitis, necrosis → surgical)
- Acute (classic presentation)
- Recurrent (~5–10% recurrence after successful reduction; recurrent intussusception should prompt investigation for a lead point)
- Chronic (rare; partial, intermittent symptoms over weeks)
Clinical Features
| Symptom | Pathophysiological Basis | Notes |
|---|---|---|
| Intermittent, severe colicky abdominal pain | Peristalsis contracting against the obstructing intussusceptum creates waves of visceral pain. Pain is colicky (comes and goes) because peristalsis is rhythmic — the child screams and draws up their knees during a wave, then becomes quiet between episodes | Classical triad component [3]; the "screaming episodes" with leg-drawing are very characteristic |
| Inconsolable crying / irritability | Same mechanism as above; infants cannot verbalise pain, so they cry and become irritable. Between episodes, the child may appear surprisingly well (the "lucid interval") | May be the only presenting symptom in young infants |
| Vomiting | Initially non-bilious (reflex vomiting from pain and vagal stimulation). As obstruction progresses and becomes complete, vomiting becomes bilious (green) because the obstruction is distal to the ampulla of Vater → bile cannot pass distally and refluxes proximally [3] | Bilious vomiting in any infant is a surgical emergency until proven otherwise |
| "Red currant jelly stool" | Venous congestion of the intussusceptum → mucosal ooze of blood and mucus → mixed stool that looks like redcurrant jelly. This is a LATE sign (appears 12–24+ hours after onset) — its absence does NOT exclude intussusception | Classical triad component [1][2][3]; present in only ~50–60% of cases. May be detected on PR examination before being visible in the nappy |
| Pallor / lethargy / "shock-like" episodes | Autonomic response to visceral pain (vagal activation); also progressive dehydration from vomiting and third-spacing. Severe lethargy can mimic sepsis or a neurological emergency | Sometimes described as "altered consciousness" — a well-known atypical presentation that can mislead clinicians [2] |
| Refusal to feed | Pain, nausea, and obstruction make the child reluctant to eat | Non-specific but important in context |
| Diarrhoea (early) | Increased peristalsis early in the course may produce loose stools before obstruction becomes complete | Can mimic acute gastroenteritis initially, which is a classic diagnostic pitfall |
| Preceding URTI or gastroenteritis symptoms | Viral infection → Peyer's patch hyperplasia → acts as lead point | Very common history to elicit; supports the idiopathic viral trigger hypothesis |
The Classical Triad (present in < 50% of cases!)
- Intermittent colicky abdominal pain
- "Red currant jelly" stool (blood and mucus per rectum)
- Sausage-shaped abdominal mass (RUQ)
Fewer than 50% of children present with all three components [3]. Do NOT wait for the full triad to make the diagnosis — a high index of suspicion is needed. Many infants present with only one or two features. Lethargy alone can be the presenting complaint.
| Sign | Pathophysiological Basis | Notes |
|---|---|---|
| Sausage-shaped mass in the RUQ / right hypochondrium | The intussusceptum (usually ileocolic) has telescoped through the ICV and now sits in the ascending colon / hepatic flexure region, forming a palpable cylindrical mass | Classical triad component [3]; best palpated between episodes of colic (when the abdomen is relaxed). May be missed if the child is crying/guarding |
| "Empty" right iliac fossa (Dance's sign) | The caecum and terminal ileum have been dragged out of the RIF by the intussusception, leaving the RIF feeling unusually empty on palpation | A classic but subtle sign; not always present |
| Abdominal distension | Progressive mechanical bowel obstruction → proximal bowel dilates with gas and fluid | Worsens with time; indicates later-stage obstruction |
| Abdominal tenderness / guarding / rigidity | If ischaemia progresses to transmural necrosis or perforation → peritonitis → localised or generalised peritoneal irritation | Peritonitis is a contraindication to non-operative reduction and indicates the need for surgery [3] |
| Blood and/or mucus on per rectal (PR) examination | Even when currant jelly stool is not visible in the nappy, a PR exam may reveal blood-stained mucus on the examining finger — this represents early mucosal ooze from venous congestion | Always perform a PR examination in a child with suspected intussusception — it can clinch the diagnosis |
| Palpable mass on PR | In a long intussusception that has advanced distally, the apex of the intussusceptum may be palpable as a mass on rectal examination. Very rarely, it may even prolapse through the anus | Rare but pathognomonic |
| Dehydration signs | Vomiting + poor intake + third-spacing into oedematous bowel wall → intravascular volume depletion → tachycardia, dry mucous membranes, sunken fontanelle, reduced skin turgor, reduced urine output | Assess hydration status systematically; critical for resuscitation prior to any reduction attempt |
| Tachycardia / hypotension (late) | Hypovolaemia from dehydration and/or sepsis from bowel necrosis/perforation | Late ominous signs |
| Fever | May reflect underlying viral trigger, or complicating bowel necrosis/perforation with secondary bacterial infection | New-onset fever in a child with intussusception should raise concern for ischaemia/perforation |
These are commonly tested because they catch clinicians off-guard:
-
Lethargy / altered consciousness as the predominant feature — can mimic encephalitis, sepsis, or metabolic emergency. The mechanism is thought to involve massive vagal stimulation and endogenous opioid release from visceral pain → "obtunded" appearance [2].
-
Painless intussusception — especially in very young infants or immunocompromised children.
-
Predominantly neurological presentation — e.g. seizure-like episodes (actually severe pain episodes).
-
Diarrhoea mimicking gastroenteritis — early increased peristalsis → loose stools; the child may be initially treated for gastroenteritis, delaying diagnosis.
-
Recurrent intussusception — ~5–10% recurrence rate after successful non-operative reduction; recurrence ≥ 3 times should trigger investigation for a pathological lead point.
| Time from onset | Features |
|---|---|
| 0–6 hours | Sudden colicky pain, crying, vomiting (initially non-bilious), +/- drawing up legs |
| 6–12 hours | Increasing pain episodes, bilious vomiting, lethargy between episodes, dehydration |
| 12–24 hours | Red currant jelly stool appears, palpable mass, progressive obstruction |
| > 24 hours | Risk of bowel ischaemia, necrosis, perforation, peritonitis, septic shock |
Key point for clinical practice in Hong Kong: At Queen Mary Hospital and other HA hospitals, the standard approach is that any infant 6–36 months presenting with acute colicky abdominal pain ± vomiting should have intussusception high on the differential. An ultrasound abdomen should be obtained urgently, as it is the primary diagnostic modality in local practice [3].
- Explain to parents in plain language: "Part of the bowel has folded into itself like a telescope. This is causing a blockage and pain."
- Reassure that in most cases (75–95%), it can be fixed without surgery using air or fluid pressure.
- Informed consent for the reduction procedure must include the small risk of bowel perforation (~0.5–2.5%).
- Keep the family informed at every step — parents are understandably extremely anxious when their infant is in severe pain.
High Yield Summary
- Definition: Telescoping of proximal bowel (intussusceptum) into distal bowel (intussuscipiens); most common abdominal emergency in early childhood.
- Epidemiology: Peak at 6–36 months, M > F (3:2), ~75–90% idiopathic in children.
- Aetiology: Idiopathic (viral → Peyer's patch hyperplasia) vs. pathological lead point (Meckel's, polyp, lymphoma, HSP, duplication cyst). Think lead point if age > 3–6 years or recurrent.
- Location: Ileocolic ~85–90%; ileo-ileal in HSP/post-op.
- Pathophysiology cascade: Telescoping → mesenteric drag → venous congestion → mucosal ooze (currant jelly stool) → arterial compromise → ischaemia → necrosis → perforation → peritonitis.
- Classical triad (< 50% present with all three): Colicky abdominal pain, red currant jelly stool, sausage-shaped RUQ mass.
- Don't miss: Bilious vomiting = surgical emergency. Lethargy can be the sole presentation. Always do a PR exam.
- USG abdomen is the diagnostic investigation of choice — target sign, pseudo-kidney sign [3].
- Treatment: Fluoroscopic-guided pneumatic reduction (75–95% success) — surgical reduction if failed, peritonitis, or suspected pathological lead point [3].
Active Recall - Intussusception (Definition, Epidemiology, Aetiology, Clinical Features)
[1] Lecture slides: GC 142. A child with loose stool.pdf [2] Senior notes: felixlai.md (Intussusception section) [3] Senior notes: maxim.md (Intussusception section) [4] Senior notes: Adrian Lui Pediatrics.pdf (p249–250, Meckel's diverticulum) [5] Senior notes: Ryan Ho GI.pdf (p134, Intussusception; p161, Meckel's diverticulum)
Differential Diagnosis of Intussusception in Children
A child presenting with the cardinal features of intussusception — colicky abdominal pain, vomiting, rectal bleeding, and/or lethargy — shares these features with a number of other paediatric surgical and medical emergencies. The key challenge is to distinguish intussusception from its mimics quickly, because delayed diagnosis leads to bowel ischaemia and perforation, while misdiagnosis may mean unnecessary interventions or missed alternative emergencies.
The differential diagnosis is best organised by presenting symptom complex, because children with intussusception rarely present with the full classical triad. The three major symptom clusters that drive the differential are:
- Acute colicky abdominal pain ± vomiting (the intestinal obstruction picture)
- Rectal bleeding / bloody stool (the lower GI bleeding picture)
- Lethargy / altered consciousness (the neurological mimic picture)
Detailed Differential Diagnosis by Presentation
These are conditions that mimic the obstructive component of intussusception — colicky pain, vomiting (especially bilious), abdominal distension.
| Condition | Key Distinguishing Features | Why It Mimics Intussusception | How to Differentiate |
|---|---|---|---|
| Malrotation with midgut volvulus [4][6] | Usually presents in first days to weeks of life (75% within first month); bilious vomiting is the hallmark; abdominal tenderness from peritonitis or ischaemic bowel; can present at any age | Both cause bilious vomiting and can progress to bowel ischaemia. Volvulus also involves mesenteric vascular compromise | Age (neonates > infants); upper GI contrast study shows abnormal position of DJ flexure (not in LUQ); AXR may show paucity of bowel gas. This is the most dangerous mimic — bilious vomiting in a neonate is malrotation with volvulus until proven otherwise [4] |
| Incarcerated inguinal hernia [5] | Irreducible, tender, erythematous groin swelling; pain and irritability, vomiting, cyanosis of the mass; due to patent processus vaginalis (PPV) in children (indirect hernia) | Both cause intestinal obstruction with vomiting and colicky pain in infants of similar age | Clinical examination of the groins — this is why you must ALWAYS examine the inguinal regions in any infant with vomiting or irritability. A tender, non-reducible lump is diagnostic |
| Acute appendicitis [4][5] | Migration of pain from periumbilical to RIF; low-grade fever; anorexia; RIF tenderness with guarding; more likely to be complicated in children (delayed presentation); periappendiceal fat stranding on imaging | Both can cause RLQ/RIF pain and vomiting. In younger children (< 5 years), appendicitis presents atypically and can be confused with intussusception | Age (appendicitis more common > 5 years); pain pattern (appendicitis = constant migratory pain vs intussusception = intermittent colicky pain); no bloody stool in appendicitis typically; USG will show different findings (non-compressible appendix > 6mm vs target sign) |
| Mesenteric adenitis [4][5] | Preceding URTI and high fever ± cervical lymph nodes; usually central 'colicky' pain but can cause RLQ pain; self-limiting | Both can follow a viral illness. Both can cause central/RLQ pain. Both occur in similar age groups | No obstruction features (no bilious vomiting, no abdominal distension); USG shows enlarged mesenteric lymph nodes without intussusception signs; tends to resolve spontaneously. The viral prodrome is longer and more prominent |
| Meckel's diverticulitis [4][5] | Pain may be similar but signs can be central or left-sided; may have history of antecedent abdominal pain or intermittent LGIB; peritoneal signs if perforated | Causes acute abdominal pain with peritoneal irritation that can mimic appendicitis or intussusception | Often only distinguished intra-operatively (< 10% has pre-operative diagnosis) [4]; if operating for suspected appendicitis, should run ileum for 60cm to check [4] |
| Henoch-Schönlein purpura (HSP) — abdominal involvement [4][5] | IgA-mediated small vessel vasculitis; almost always associated with ecchymotic/purpuric rash on extensor surfaces of limbs and buttocks; abdominal pain due to intestinal vasculitis (haemorrhage and oedema within bowel wall and mesentery); can itself cause intussusception (usually ileo-ileal) | HSP causes colicky abdominal pain and bloody stools — indistinguishable from primary intussusception by symptoms alone. HSP is both a mimic and a cause of intussusception | Look for the rash (palpable purpura on legs/buttocks); abdominal pain vs intussusception differentiated by USG [5]; renal involvement common — microscopic haematuria (IgAN-like picture) [4]; arthritis may be present |
| Adhesive small bowel obstruction | History of previous abdominal surgery; features of SBO (colicky pain, bilious vomiting, distension, absolute constipation) | Mechanical SBO from any cause shares symptoms | Surgical history is the key differentiator; AXR/CT shows dilated SB with transition point but no intussusception target sign |
| Post-operative intussusception [2] | Occurs after abdominal surgery (especially retroperitoneal or spinal surgery); typically ileo-ileal; presents 1–14 days post-operatively | This IS intussusception but in a specific context | Maintain high index of suspicion post-operatively; USG for diagnosis; ileo-ileal type is less likely to respond to non-operative reduction but more likely to resolve spontaneously [2] |
The Two Must-Not-Miss Diagnoses
In any infant with acute abdominal pain and bilious vomiting, the two diagnoses you absolutely must not miss are:
- Malrotation with midgut volvulus — because the entire midgut can infarct within hours
- Intussusception — because delayed treatment leads to bowel necrosis and perforation
Both are surgical emergencies. The approach is: stabilise → urgent imaging (USG for intussusception; upper GI contrast for malrotation if suspected) → definitive treatment.
These conditions mimic the "red currant jelly stool" or bloody stool component of intussusception [2][5].
| Condition | Key Distinguishing Features | Why It Mimics Intussusception | How to Differentiate |
|---|---|---|---|
| Meckel's diverticulum (bleeding) [2][5] | Massive painless altered blood (maroon-coloured stool); due to acid secretion by ectopic gastric mucosa causing ulceration of adjacent ileal mucosa; classically painless unless complicated by obstruction or diverticulitis | Both cause LGIB in young children | Painless (vs painful in intussusception); larger volume of altered blood; no mass palpable; Meckel's (Technetium-99m pertechnetate) scan detects ectopic gastric mucosa [5] |
| Bacterial colitis [2] | Acute bloody diarrhoea with mucus; fever; preceding history of contaminated food/water exposure; organisms include Salmonella, Shigella, Campylobacter, E. coli O157:H7, C. difficile | Both can cause bloody, mucoid stools with abdominal pain | Fever more prominent; diarrhoea is the primary symptom (not colicky pain); stool culture is definitive; no mass on examination; USG shows no intussusception |
| Juvenile polyp [5] | Painless rectal bleeding; bright red blood typically coating the stool; most common colorectal polyp in children (> 90% are juvenile hamartomatous polyps); peak age 2–5 years | Both can cause rectal bleeding in toddlers | Painless (no colic); bright red blood (not currant jelly); diagnosed by colonoscopy |
| Anal fissure [5] | Painful defecation; bright red blood on toilet paper or surface of stool; history of constipation (hard stools); visible fissure on inspection | Both present with blood in the stool in an infant/toddler | Outlet-type bleeding (blood on surface/wiping); painful with defecation specifically; visible on inspection; treat underlying constipation |
| Inflammatory bowel disease [1][5] | Prolonged diarrhoea (> 14 days), bloody diarrhoea; failure to thrive or weight loss; usually older children/adolescents; extraintestinal manifestations (joint, eye, skin) | Chronic bloody diarrhoea can overlap | Chronic course (weeks to months vs acute in intussusception); weight loss/growth failure; raised inflammatory markers (ESR, CRP, faecal calprotectin); colonoscopy diagnostic |
| Intestinal duplication cyst [5] | Can cause painless LGIB if contains ectopic gastric mucosa (similar mechanism to Meckel's); can also act as a pathological lead point for intussusception | Bleeding mechanism similar; can also cause intussusception | USG may show a cystic structure adjacent to bowel; Tc-99m scan if ectopic gastric mucosa suspected |
| Small bowel ischaemia (e.g. volvulus) [5] | Bilious vomiting, abdominal pain, bloody stools if bowel becomes gangrenous; signs of shock | Ischaemic bowel from any cause (including intussusception) produces bloody output | Context (neonate → think malrotation/volvulus; post-operative → think adhesions); imaging differentiates |
Clinical pearl from lecture slides: Surgical disorders (bowel obstruction, intussusception, ischaemic bowel) should be suspected when a child presents with bilious vomiting, severe or localised abdominal pain, bloody diarrhoea, and examination reveals abdominal distension, rebound tenderness, mucoid/bloody stools [1].
This is the most treacherous presentation because it can lead clinicians away from an abdominal diagnosis entirely [2].
| Condition | Key Distinguishing Features | Why It Mimics Intussusception | How to Differentiate |
|---|---|---|---|
| Sepsis / septic shock [2] | Fever, tachycardia, hypotension, poor perfusion, possible focus of infection; elevated WCC, CRP, procalcitonin, lactate | Both can cause lethargy, pallor, and shock in an infant | Septic screen (blood cultures, urine, CXR); abdominal examination and USG will differentiate — intussusception has a mass and target sign |
| Meningitis / encephalitis [1] | Persistent vomiting, altered consciousness, irritability, photophobia; petechial/purpuric rash (meningococcal), neck stiffness, bulging fontanelle in infants | Both can cause lethargy, vomiting, and irritability in infants | Neurological signs (meningism, bulging fontanelle); lumbar puncture if safe; no colicky pattern to symptoms |
| Metabolic emergency (DKA, inborn errors of metabolism) [5] | Kussmaul breathing (DKA), ketotic breath, severe dehydration; neonates/infants with IEM may have poor feeding, vomiting, encephalopathy | Both can cause vomiting, lethargy, and dehydration | Blood glucose, ketones, blood gas (metabolic acidosis), ammonia, newborn screening history |
| Non-accidental injury (NAI) | Inconsistent history; unexplained injuries; retinal haemorrhages; subdural haematomas; fractures at different stages of healing | An abused infant may present with lethargy, irritability, and vomiting | Careful history (inconsistency between history and injury pattern); skeletal survey; ophthalmoscopy; safeguarding referral |
| Post-ictal state | History of seizure activity; gradually improving conscious level; may have known epilepsy or febrile seizures | Post-ictal drowsiness mimics the lethargy of intussusception | Witnessed seizure history; improving trajectory; EEG if needed; always examine the abdomen |
Don't Forget the Abdomen!
The most common reason for delayed diagnosis of intussusception is not thinking of it. In any infant presenting with lethargy or altered consciousness, ALWAYS examine the abdomen and perform a PR examination. If there is any doubt, get an urgent USG abdomen. Missing intussusception in a "lethargic infant" is a well-known examination scenario and a real-world diagnostic pitfall [2].
The following table summarises the critical distinguishing features between intussusception and its closest mimics:
| Feature | Intussusception | Malrotation + Volvulus | Incarcerated Hernia | Appendicitis | HSP | Meckel's Bleeding |
|---|---|---|---|---|---|---|
| Typical age | 6–36 months | Neonates (< 1 month) | Any infant | > 5 years (usually) | 3–10 years | < 2 years |
| Pain pattern | Intermittent colicky | Constant, progressive | Constant | Migratory → constant | Colicky | Usually painless |
| Vomiting | Non-bilious → bilious | Bilious from onset | Present | Present (late) | Present | Absent/mild |
| Stool | Currant jelly (late) | Bloody (very late) | Normal initially | Normal | Bloody, mucoid | Painless maroon/altered blood |
| Mass | Sausage-shaped RUQ | None typically | Inguinal lump | RIF tenderness | None | None |
| Rash | None | None | None | None | Purpura on legs/buttocks | None |
| Key investigation | USG: target sign | Upper GI contrast | Clinical exam | USG / CT | USG ± clinical | Tc-99m scan |
- Rotavirus gastroenteritis remains a common preceding illness in Hong Kong before intussusception, given that rotavirus vaccination is not part of the government programme and uptake is variable.
- Bacterial colitis from Salmonella and Campylobacter is relatively common in Hong Kong due to local food practices → these must be considered in children with bloody diarrhoea [1].
- HSP is not uncommon in Hong Kong children and is a recognised both as a differential and a cause of intussusception — always look at the skin.
- Bilious vomiting in any infant or child should be treated as a surgical emergency until proven otherwise — this is a fundamental paediatric principle emphasised across all Hong Kong training programmes [1][4].
High Yield Summary — Differential Diagnosis of Intussusception
- Organise by presentation: (a) colicky pain/obstruction, (b) rectal bleeding, (c) lethargy.
- Most dangerous mimic: Malrotation with midgut volvulus — bilious vomiting in a neonate is volvulus until proven otherwise.
- Don't forget: Always check the inguinal regions (incarcerated hernia) and the skin (HSP purpura).
- HSP is both a differential AND a cause — IgA vasculitis causes bowel wall oedema → ileo-ileal intussusception; differentiate from primary intussusception by USG [5].
- Meckel's diverticulum causes painless massive rectal bleeding (vs painful + currant jelly in intussusception) and can be a pathological lead point for intussusception itself.
- Atypical presentation: Lethargy → always examine the abdomen and get USG. Differential includes sepsis, meningitis, NAI, metabolic emergencies.
- Key lecture slide point: Surgical disorders should be suspected with bilious vomiting, severe/localised abdominal pain, bloody diarrhoea, abdominal distension, rebound tenderness, mucoid/bloody stools [1].
- USG abdomen is the first-line investigation to differentiate intussusception from its mimics (target sign, pseudo-kidney sign) [3][5].
Active Recall - Differential Diagnosis of Intussusception
References
[1] Lecture slides: GC 142. A child with loose stool.pdf (p19, Table 3.3) [2] Senior notes: felixlai.md (Intussusception section — Differential diagnosis, Clinical manifestation) [3] Senior notes: maxim.md (Intussusception section) [4] Senior notes: Adrian Lui Pediatrics.pdf (p248–250, Appendicitis differentials, Malrotation, Intussusception) [5] Senior notes: maxim.md (GI bleed section, Meckel diverticulum, HSP, Paediatric surgical abdomen) [6] Senior notes: felixlai.md (Intestinal malrotation section)
Diagnostic Criteria, Algorithm, and Investigations for Intussusception in Children
Intussusception does not have a single universally agreed "diagnostic criteria checklist" in the way that, say, rheumatic fever has the Jones criteria. Instead, the diagnosis is made by combining clinical suspicion (based on history and examination) with confirmatory imaging. In practical paediatric emergency medicine, the diagnostic pathway is:
- Clinical suspicion — raised by any combination of the cardinal features (colicky pain, vomiting, bloody stool, palpable mass, lethargy) in an infant aged 6–36 months.
- Imaging confirmation — USG abdomen is the diagnostic gold standard [3][7].
- Therapeutic confirmation — in some cases, successful enema reduction (pneumatic or hydrostatic) simultaneously confirms the diagnosis and treats the condition.
There Is No Formal 'Scoring System' for Intussusception
Unlike appendicitis (where the Alvarado/PAS score exists), intussusception relies on clinical gestalt + ultrasound. The key message is: if you think of it, image it. The threshold to obtain an urgent USG should be very low in any infant with unexplained abdominal pain, vomiting, or irritability.
Brighton Collaboration Case Definition (Used in Vaccine Safety Surveillance)
For epidemiological and vaccine-safety purposes, the Brighton Collaboration provides a standardised case definition of intussusception with three levels of diagnostic certainty [7]:
| Level | Criteria |
|---|---|
| Level 1 (Definite) | Surgical confirmation (intussusception found at laparotomy or laparoscopy), OR autopsy findings, OR air/liquid enema reduction with confirmation of intussusception by imaging |
| Level 2 (Probable) | Two or more of the following: (a) characteristic imaging findings (USG target sign/pseudo-kidney sign; CT target/donut lesion), (b) characteristic clinical features (abdominal mass, bloody stool, signs of IO), (c) pathological lead point found |
| Level 3 (Possible) | Clinical features suggestive of intussusception without imaging or surgical confirmation |
In clinical practice (as opposed to surveillance), Level 1 or Level 2 is what we aim for — i.e., USG confirmation + clinical features, or confirmation at surgery/enema.
Investigation Modalities — Detailed Breakdown
1. Bedside Investigations
- What it tells you: Blood and/or mucus on the examining finger (early mucosal ooze from venous congestion) even before currant jelly stool is visible in the nappy. Occasionally the apex of the intussusceptum is palpable as a mass.
- Why it matters: This is a rapid, no-cost bedside test that can clinch the diagnosis and is often the finding that tips the clinician toward ordering an urgent USG.
- Paediatric consideration: Explain the procedure to the caregiver and obtain consent. Use a well-lubricated little finger in an infant. It should not be deferred "because the child is crying" — in a child with suspected intussusception, the information gained is critical.
| Parameter | What to look for | Why |
|---|---|---|
| Heart rate | Tachycardia (age-appropriate: e.g. > 160 bpm in infant) | Dehydration from vomiting, third-spacing; pain; or sepsis if perforation |
| Blood pressure | Hypotension (late sign in children) | Hypovolaemic or septic shock |
| Temperature | Fever | Underlying viral trigger, or complicating bowel necrosis/peritonitis |
| Capillary refill time | > 2 seconds | Poor perfusion from dehydration/shock |
| Fontanelle (if open) | Sunken | Dehydration |
These are not diagnostic of intussusception per se, but are essential for assessing the child's physiological status, guiding resuscitation, and preparing for potential surgery [8][9].
| Test | What to look for | Pathophysiological basis |
|---|---|---|
| CBC | Leucocytosis (↑WCC with neutrophilia) | Stress response, dehydration (haemoconcentration), or secondary bacterial infection if bowel ischaemia/perforation. Anaemia if significant LGIB. |
| Electrolytes (Na⁺, K⁺, Cl⁻, HCO₃⁻) | HypoK/hypoCl from prolonged vomiting; hyponatraemia from third-spacing + inappropriate ADH | Vomiting → loss of H⁺ and Cl⁻ → metabolic alkalosis → renal K⁺ wasting (H⁺/K⁺ exchange) [8][9] |
| RFT (Urea, Creatinine) | Raised urea:creatinine ratio (pre-renal AKI) | Dehydration from vomiting and poor intake → reduced renal perfusion → pre-renal uraemia [8][9] |
| Blood gas (capillary/venous) | Metabolic acidosis with raised lactate → bowel ischaemia. Metabolic alkalosis → prolonged vomiting [8][9] | Ischaemic bowel switches to anaerobic metabolism → lactic acid production. Vomiting loses gastric H⁺ → alkalosis |
| CRP | Elevated if necrosis, perforation, or secondary peritonitis | Non-specific inflammatory marker; rising CRP with clinical deterioration suggests complication |
| Group & Save / Cross-match | Prepare for potential surgery | All children with suspected surgical abdomen should have blood available |
| Coagulation profile | Usually normal; abnormal if DIC from sepsis | If perforation → peritonitis → sepsis → DIC → consumptive coagulopathy |
| Blood glucose | Hypoglycaemia (infants have low glycogen reserves; stress + fasting) | Always check in any acutely unwell infant — hypoglycaemia can compound the clinical picture |
Paediatric Normal Values — Know Your Ranges
Always interpret blood results against age-appropriate normal ranges:
- Neonatal WCC: 10–26 × 10⁹/L (normally higher than older children)
- Infant WCC: 6–17.5 × 10⁹/L
- Creatinine: much lower in infants (15–30 µmol/L) than adults
- Lactate: normal < 2 mmol/L in children; > 2 mmol/L is concerning for ischaemia
3. Radiological Investigations
Role: Performed as part of the evaluation of patients with abdominal symptoms and to exclude perforation in patients with suspected intussusception [7]. AXR is NOT diagnostic of intussusception on its own — its main value is to look for complications (perforation, obstruction) and to exclude other diagnoses. Some centres now skip AXR and go straight to USG.
Key findings on AXR [7][8][9]:
| Finding | Description | Significance |
|---|---|---|
| Distended loops of small bowel with absence of colonic gas [3][7] | Proximal small bowel dilated (> 3 cm); no gas seen in the colon (because the intussusception blocks passage of gas distally) | Supports the diagnosis of mechanical bowel obstruction at the level of the ileocaecal region |
| Air-fluid levels (on erect film) | Multiple air-fluid levels in the small bowel | Sign of small bowel obstruction (> 5 air-fluid levels is diagnostic of IO) [8][9] |
| "Target sign" (AXR) [7] | Two concentric radiolucent circles superimposed on the right kidney — representing peritoneal fat surrounding and within the intussusception | Relatively specific when seen, but not commonly identified on plain film |
| "Crescent sign" [7] | A soft-tissue density representing the intussusceptum projecting into the gas of the large bowel | The head of the intussusceptum is outlined by colonic gas |
| "Sausage-shaped opacity" [9] | A soft-tissue mass in the RUQ/transverse colon region corresponding to the intussusception itself | May be visible, especially if the colon is relatively gas-free |
| Pneumoperitoneum (on erect CXR or AXR) | Free gas under the diaphragm (erect CXR) or Rigler's sign (gas on both sides of bowel wall on supine AXR) | Indicates perforation — contraindication to enema reduction → proceed directly to surgery |
| Normal AXR | No specific findings | A normal AXR does NOT exclude intussusception — sensitivity is only ~45–50%. Must proceed to USG if clinical suspicion remains |
AXR Is Not Enough
A normal AXR does not rule out intussusception. The AXR may appear entirely normal in early intussusception before significant obstruction develops. If you suspect intussusception clinically, you MUST proceed to USG regardless of the AXR result [7]. The main purpose of the AXR is to check for perforation (free gas) before attempting enema reduction.
USG is the imaging modality of choice to identify intussusception [3][7].
Why USG is ideal in paediatrics:
- No ionising radiation — critical in children (ALARA principle: As Low As Reasonably Achievable)
- Non-invasive and painless — can be performed at the bedside
- Sensitivity and specificity can approach 100% in experienced hands [7]
- Able to detect pathological lead points [7]
- Can monitor success of reduction procedure [7]
- Can assess bowel wall perfusion (Doppler) to evaluate for ischaemia
Classical USG findings [3][7]:
| View | Finding | Description | Pathophysiological explanation |
|---|---|---|---|
| Transverse | "Target sign" (also called "doughnut" or "bull's-eye" sign) [3][7] | Multiple concentric rings seen on cross-section — alternating hypoechoic (bowel wall) and hyperechoic (mesenteric fat, mucosa) layers | The intussusceptum is surrounded by the intussuscipiens → layering of bowel wall + mesentery + bowel wall creates concentric rings, like a target or doughnut |
| Longitudinal | "Pseudo-kidney sign" [3][7] | An elongated mass with a hyperechoic centre (mesenteric fat of intussusceptum) and hypoechoic rim (bowel wall of intussuscipiens) | In longitudinal section, the layered structure looks like a kidney — the central "hilum" is the trapped mesentery, the "cortex" is the outer bowel wall |
| Doppler | Lack of perfusion in intussusceptum indicates development of ischaemia [7] | Absent or markedly reduced blood flow within the intussusceptum on colour Doppler | Mesenteric vessel compression → no arterial flow detectable → implies ischaemia, increasing urgency for reduction or surgery |
| Lead point | Mass within the intussusceptum | A discrete mass (polyp, Meckel's, lymphoma) at the apex of the intussusception | The lead point is the structural lesion that initiated the telescoping |
Additional USG features to assess:
- Outer diameter of the intussusception: typically > 3 cm (often 2.5–5 cm)
- Trapped fluid between layers: indicates oedema; large amounts suggest ischaemia and lower likelihood of successful non-operative reduction
- Free peritoneal fluid: suggests advanced disease; if significant, lower success rate of enema reduction
- Lymph nodes: enlarged mesenteric lymph nodes may be seen (consistent with viral trigger or mesenteric adenitis)
USG Interpretation — What the Signs Mean Physically
Imagine cutting through a telescoped bowel (like cutting through a rolled-up newspaper):
- Transverse cut → you see concentric rings (target/doughnut sign)
- Longitudinal cut → you see a layered sausage with a bright centre (the trapped mesentery fat) resembling a kidney (pseudo-kidney sign)
The more layers you see, the more bowel has telescoped in. The presence of trapped fluid between layers and absence of Doppler flow are ominous signs.
In older practice, a barium enema was used diagnostically (and could be therapeutic). This has largely been replaced by pneumatic (air) enema or hydrostatic (saline) enema under fluoroscopic or USG guidance, which serves the dual purpose of diagnosis and treatment [3][5]. The diagnostic findings on contrast/air enema are:
| Finding | Description |
|---|---|
| "Meniscus sign" or "coiled-spring sign" | Contrast (or air) outlines the intussusceptum within the colon — the leading edge appears as a meniscus (crescent), and the compressed mucosal folds of the intussusceptum create a coiled-spring appearance |
| "Claw sign" | The contrast or air columns around the intussusceptum create a claw-like indentation at the apex of the intussusception |
| Obstruction to retrograde flow | Contrast/air cannot pass beyond the point of intussusception |
| Successful reduction | Gush of air into the terminal ileum (in pneumatic reduction) or free flow of contrast into the small bowel — confirms complete reduction [3] |
In modern Hong Kong paediatric practice, USG is performed first for diagnosis, and if intussusception is confirmed and there are no contraindications, the child proceeds to fluoroscopic-guided pneumatic reduction [3].
CT scan is reserved for patients in whom other imaging modalities are unrevealing or to characterise pathological lead points for intussusception detected by USG [7].
| Feature | Detail |
|---|---|
| When to use | Atypical presentations; older children where a pathological lead point (e.g. lymphoma) is suspected; unclear USG findings; to assess for complications (perforation, abscess) |
| Key findings | "Target sign" (alternating hypodense and hyperdense layers) [7][9]; pathological lead point (mass); bowel wall thickening; mesenteric oedema; free fluid; pneumatosis intestinalis and portal venous gas if ischaemia/necrosis [7][9] |
| Disadvantage | Exposes patients to substantial radiation [7] — in paediatrics, CT should only be used when the information gained outweighs the radiation risk |
Radiation Awareness in Paediatric Imaging
Children are significantly more sensitive to ionising radiation than adults (higher radiosensitivity of dividing cells + longer remaining lifespan for cancer to develop). The hierarchy of imaging for intussusception should be:
- USG (no radiation, diagnostic)
- AXR (low radiation, for obstruction/perforation screening)
- CT (high radiation, reserved for complex/unclear cases or to characterise lead points)
Never jump to CT when USG can answer the question [7].
| Investigation | Role | Key Findings in Intussusception | Sensitivity/Specificity | When to Use |
|---|---|---|---|---|
| PR examination | Bedside; detect occult blood | Blood/mucus on finger; rarely palpable mass | High clinical utility | Always — in every suspected case |
| Bloods | Assess physiology, prep for surgery | Leucocytosis, electrolyte derangement, metabolic acidosis/raised lactate if ischaemia | Non-diagnostic | Always |
| AXR (supine ± erect) | Screen for obstruction/perforation | Distended SB, absent LB gas [3]; target/crescent sign (uncommon); free gas if perforated | Sensitivity ~45–50%; poor for excluding | First-line alongside USG; mainly to exclude perforation |
| USG abdomen | Diagnostic gold standard [3][7] | Target/doughnut sign (transverse); pseudo-kidney sign (longitudinal); trapped fluid; absent Doppler flow if ischaemic; detect lead point | Sensitivity ~98–100%; specificity ~98–100% [7] | All suspected cases |
| Pneumatic/hydrostatic enema | Diagnostic + therapeutic | Meniscus/claw/coiled-spring sign; successful reduction = gush of air into terminal ileum | Very high (performed under fluoroscopic guidance) | After USG confirms diagnosis and no contraindications |
| CT abdomen | Complex/atypical cases | Target/donut lesion; lead point characterisation; complications (pneumatosis, portal gas) | Very high but radiation cost | Only if USG unclear or to characterise lead point in older children |
Before proceeding to enema reduction, you must ensure there are no contraindications. These are critical because attempting reduction in these circumstances risks perforation, peritoneal contamination, and death [3][5]:
| Contraindication | Rationale |
|---|---|
| Peritonitis / signs of peritoneal irritation [3] | Suggests bowel necrosis or perforation already present — enema pressure would worsen perforation |
| Pneumoperitoneum on AXR/CXR | Confirmed perforation — requires emergency laparotomy |
| Haemodynamic instability / shock unresponsive to resuscitation | Child too unstable for enema; needs surgery |
| Suspected pathological lead point (e.g. lymphoma, large polyp) [3] | Non-operative reduction may temporarily reduce the intussusception but does not address the underlying lesion; recurrence is very likely; the lead point needs surgical excision and histological diagnosis |
| Prolonged symptoms (> 48 hours) with signs of bowel compromise | Higher likelihood of gangrenous bowel; lower success rate of reduction; higher perforation risk |
High Yield Summary — Diagnosis of Intussusception
- Diagnosis is clinical suspicion + USG confirmation. There are no formal "diagnostic criteria" in daily practice — use the Brighton case definition for surveillance.
- USG abdomen is the imaging modality of choice: target sign (transverse), pseudo-kidney sign (longitudinal), ± absent Doppler flow (ischaemia), ± visible lead point. Sensitivity and specificity approach 100% [3][7].
- AXR is performed to screen for obstruction and exclude perforation (free gas) — a normal AXR does NOT exclude intussusception.
- CT is reserved for atypical/complex cases or to characterise pathological lead points. Avoid unnecessary radiation in children.
- Bloods are for physiological assessment and pre-operative preparation — not for diagnosis. Key findings: leucocytosis, metabolic acidosis with raised lactate (ischaemia), electrolyte derangement from vomiting.
- Contraindications to enema reduction: peritonitis, perforation (pneumoperitoneum), shock, suspected pathological lead point [3].
- Fluoroscopic-guided pneumatic reduction is both diagnostic and therapeutic — successful reduction confirmed by gush of air into the terminal ileum [3].
- Always do a PR examination — blood/mucus on the finger may be the first objective sign.
Active Recall - Diagnosis of Intussusception
References
[3] Senior notes: maxim.md (Intussusception section) [5] Senior notes: maxim.md (Paediatric surgical abdomen; GI bleed section; Meckel diverticulum section) [7] Senior notes: felixlai.md (Intussusception — Diagnosis section) [8] Senior notes: Ryan Ho Fundamentals.pdf (p279, Investigations for acute abdomen) [9] Senior notes: Ryan Ho GI.pdf (p134, Intussusception; p136, Diagnostic evaluation of IO; p105, Investigations for acute abdomen)
Management of Intussusception in Children
The management of paediatric intussusception follows a clear logical sequence:
- Resuscitate and stabilise — before anything else, correct dehydration and physiological derangement.
- Determine suitability for non-operative reduction — check for contraindications.
- Attempt non-operative reduction (pneumatic or hydrostatic enema) — this is the first-line treatment in the vast majority of children [3][7][10].
- Proceed to surgery if non-operative reduction fails or is contraindicated [3][7][10].
- Post-reduction monitoring — observe for recurrence and complications.
- Investigate for pathological lead point — especially in recurrent, atypical, or older-child cases.
The beauty of paediatric intussusception management (compared to adults) is that most cases can be treated non-operatively with excellent success rates. In adults, intussusception almost always requires formal surgical resection because there is nearly always a pathological lead point (often malignant) [9].
Before any reduction attempt, the child must be adequately resuscitated. This is because:
- Dehydrated, hypovolaemic children tolerate procedures poorly and are at higher risk of cardiovascular collapse.
- Electrolyte derangements (especially hypokalaemia from vomiting) predispose to cardiac arrhythmias under anaesthesia.
- The enema reduction procedure itself carries a small risk of perforation → the child must be in the best possible physiological state.
| Step | Detail | Rationale |
|---|---|---|
| IV access | Secure at least one reliable cannula (22G in infant; 20G in older child); send bloods | Need for fluid resuscitation and potential emergency surgery |
| NPO (nil per os) [10] | Nothing by mouth from the moment intussusception is suspected | Risk of aspiration during reduction procedure or if emergency surgery required; reduces further bowel distension |
| IV fluid resuscitation | NS or Hartmann's solution; bolus 20 mL/kg if clinically dehydrated or shocked, reassess, repeat if needed [10] | Replace intravascular volume lost through vomiting, third-spacing into oedematous bowel wall, and poor intake. Use isotonic crystalloids — not dextrose-only solutions, as these do not expand intravascular volume effectively |
| NG tube decompression [10] | Insert NG tube (8Fr in infants, 10–12Fr in older children); place on free drainage with 4-hourly aspiration | Decompress proximal bowel → reduces distension, decreases risk of aspiration during induction of anaesthesia, reduces intraluminal pressure that may worsen ischaemia [10] |
| Analgesia | IV paracetamol (15 mg/kg) as first-line; IV morphine (0.1 mg/kg) or intranasal fentanyl for severe pain | Children in severe pain from colicky intussusception need adequate analgesia. Paracetamol alone is often insufficient for visceral colic; opioids may be required. In paediatrics, always use weight-based dosing |
| Prophylactic IV antibiotics [7][10] | Broad-spectrum cover (e.g., IV co-amoxiclav 30 mg/kg or IV cefuroxime + metronidazole) | Due to risk of perforation during reduction and because obstructed, ischaemic bowel undergoes bacterial translocation (bacteria crossing the compromised mucosal barrier into the bloodstream) [7] |
| Correct electrolytes | Check K⁺, Na⁺, Cl⁻, HCO₃⁻, glucose; replace as needed | HypoK and hypoCl from prolonged vomiting [8][9]; hypoglycaemia risk in fasting infants (low glycogen stores) |
| Group & Save / Cross-match | Type and screen blood | Must be available in case emergency surgery with potential bowel resection is required |
| Urinary catheter | Consider if shocked or heading to theatre | Monitor urine output (target > 1 mL/kg/hr in children) as a marker of end-organ perfusion |
'Drip and Suck' — The Universal IO Management Principle
"Drip and suck" is the standard supportive management for any intestinal obstruction [10]:
- "Drip" = IV fluids (replace losses, maintain hydration)
- "Suck" = NG tube decompression (decompress the proximal bowel)
This applies to intussusception as much as to any other cause of IO. Get these running immediately while organising definitive treatment.
Phase 2: Non-Operative Reduction — First-Line Definitive Treatment
Non-operative enema reduction is the preferred first treatment for paediatric intussusception with a high success rate (75–95%) [3][7].
There are two techniques: pneumatic (air) and hydrostatic (liquid). Both work on the same principle — applying retrograde pressure through the rectum to push the intussusceptum back out of the intussuscipiens, like un-telescoping a tube by blowing air or pushing fluid backward through it.
| Aspect | Detail |
|---|---|
| Principle | Air is insufflated per rectum under controlled pressure → the air column exerts retrograde pressure on the intussusceptum → gradually pushes it proximally back through the ileocaecal valve |
| Guidance | Fluoroscopic guidance — allows real-time visualisation of the air column and the intussusception as it reduces [3] |
| Technique | Insert 18–22 Fr Foley catheter into rectum, inflate the balloon to seal the anus, connect to a pressure-limited air insufflator. Maintain pressure at ~100–120 mmHg for ~3 minutes per attempt. Observe for a gush of air into the terminal ileum which confirms successful reduction [3] |
| Advantages over hydrostatic | Pneumatic technique reduces intussusception more easily [7]; if perforation occurs, air is less harmful to the peritoneum than barium (barium peritonitis is catastrophic); faster procedure |
| Success rate | 75–95% [3] |
| Number of attempts | Up to 2–3 attempts are generally considered reasonable before declaring failure; some centres use a "delayed repeat attempt" strategy (wait 30–60 min and retry) |
| Confirmation of complete reduction | Gush of air into the terminal ileum on fluoroscopy [3]; relief of clinical symptoms; disappearance of the abdominal mass on palpation |
"Successful reduction is indicated by appearance of water and bubbles in terminal ileum, free flow of contrast or air into terminal ileum, relief of symptoms, and disappearance of abdominal mass" [7].
| Aspect | Detail |
|---|---|
| Principle | Warm normal saline (or occasionally dilute contrast) is instilled per rectum under gravity or controlled pressure → fluid column pushes intussusceptum back |
| Guidance | USG guidance — now increasingly the intervention of choice [7]; allows direct visualisation of the intussusception reducing in real-time without radiation |
| Technique | Foley catheter into rectum; saline reservoir at a height of ~100 cm above the patient (generates hydrostatic pressure ~75–80 mmHg); monitor with USG for disappearance of target sign and free flow of saline into terminal ileum |
| Advantages | No ionising radiation (can be performed entirely under USG); readily available |
| Disadvantages | Slightly lower success rate than pneumatic in some studies; if perforation occurs, saline spillage is less harmful than barium but more voluminous than air |
Pneumatic vs. Hydrostatic — Which to Choose?
Pneumatic technique using air or CO₂ reduces intussusception more easily and is more advantageous if perforation occurs [7]. However, USG-guided hydrostatic reduction with saline is now increasingly popular because it avoids all radiation exposure — particularly valuable in paediatrics.
In Hong Kong HA hospitals, both modalities are available. The choice often depends on local expertise and radiologist preference. At institutions with strong paediatric radiology USG capability (e.g. Queen Mary Hospital, Prince of Wales Hospital), USG-guided hydrostatic reduction is commonly performed. Where fluoroscopic facilities are more established, pneumatic reduction may be preferred [3].
These are the situations where you must NOT attempt enema reduction and should proceed directly to surgery [3][7][10]:
| Contraindication | Rationale |
|---|---|
| Peritonitis (generalised abdominal tenderness, guarding, rigidity) [3] | Peritonitis implies bowel necrosis and/or perforation — applying enema pressure would worsen contamination and perforation |
| Perforation / pneumoperitoneum [3][7][10] | Confirmed bowel perforation on CXR/AXR (free gas under diaphragm) — further insufflation would cause tension pneumoperitoneum and cardiovascular collapse |
| Haemodynamic instability / shock unresponsive to resuscitation | Child too physiologically compromised for a semi-elective procedure; requires emergency laparotomy |
| Suspected pathological lead point [3] | Non-operative reduction may transiently succeed but the lead point remains → high recurrence rate; the lead point needs surgical excision and histological diagnosis (especially to exclude lymphoma) |
| Prolonged symptoms (> 48–72 hours) with evidence of bowel compromise | Higher risk of gangrenous bowel; very low success rate of non-operative reduction |
| Complication | Incidence | Detail |
|---|---|---|
| Bowel perforation | < 1% (pneumatic); ~0.5–2.5% overall | Risk factors: age < 6 months, long duration of symptoms, and higher pressure during reduction [7]. Pneumatic perforation → tension pneumoperitoneum (air under tension in the peritoneal cavity → can compress IVC → cardiovascular collapse); requires immediate needle decompression (14G needle in LUQ, midclavicular line) followed by emergency laparotomy [3] |
| Recurrence | ~5–10% after successful non-operative reduction [3] | Most recurrences occur within 72 hours; the vast majority can be treated with repeat enema reduction. ≥ 3 recurrences → investigate for pathological lead point |
| Incomplete reduction | Variable | The intussusception reduces partially but a residual "nubbin" of oedematous ileum remains at the ICV → may re-intussuscept. Complete reduction (free air/fluid reflux into terminal ileum) must be confirmed |
Phase 3: Surgical Management
Surgical reduction is indicated when non-operative reduction fails, is contraindicated, or when a pathological lead point is suspected [3].
| Indication | Explanation |
|---|---|
| Failed pneumatic/hydrostatic reduction (after 2–3 attempts) [3] | The intussusception cannot be reduced by retrograde pressure alone — the bowel is too oedematous, the intussusception is too tightly impacted, or the bowel has become adherent |
| Peritonitis / signs of bowel necrosis [3] | Gangrenous bowel will not reduce safely and needs resection |
| Perforation | Requires emergency laparotomy for washout and repair/resection |
| Suspected pathological lead point [3] | Need direct visualisation, excision, and histological diagnosis |
| Critically ill child | Suspected intussusception who is critically ill [7] — too unstable for a prolonged enema attempt; better served by direct surgical intervention |
| Recurrent intussusception (≥ 3 episodes) | High likelihood of a pathological lead point driving recurrence; surgical exploration indicated to identify and resect it |
| Step | Detail | Rationale |
|---|---|---|
| Approach | Laparotomy (transverse RLQ incision in children) or laparoscopy (in experienced centres); laparotomy is more common in the emergency setting | Direct visualisation and access to the bowel |
| Manual reduction [7][10] | Achieved by gently compressing the most distal part of the intussusception towards its origin [10] — this means you squeeze the intussusceptum out of the intussuscipiens by applying gentle pressure on the apex of the mass, pushing it backward/proximally. Never pull on the intussusceptum — this risks serosal tearing and perforation | The bowel wall is oedematous and fragile; gentle sustained retrograde pressure is the safest approach |
| Assessment of bowel viability [10] | After reduction, inspect the bowel for viability: colour (pink = viable, dark/black = necrotic), peristalsis (present = viable), mesenteric pulsation (palpable = viable), surface (shiny = viable, dull/lusterless = necrotic) | Necrotic bowel must be resected — leaving it in situ leads to perforation and peritonitis |
| Bowel resection + primary anastomosis | If bowel is gangrenous / non-viable: resect the affected segment and perform end-to-end or end-to-side anastomosis. In children, primary anastomosis is generally preferred over stoma formation (healthy peritoneum, good healing capacity) | Remove the source of necrosis and restore bowel continuity |
| Examine for pathological lead point | Run the terminal ileum for ~60 cm from the ileocaecal valve [4]; inspect the Meckel's diverticulum, polyps, lymphoma, or other masses | Any lead point found must be excised and sent for histological examination |
| Appendicectomy | Some surgeons perform an incidental appendicectomy if the approach is through a RLQ incision | Avoids future diagnostic confusion (the incision scar may mimic appendicectomy history) |
Surgical Rule: Squeeze, Don't Pull!
During manual operative reduction, always push the intussusceptum retrograde from its distal apex. Never grab and pull the proximal bowel — this tears the serosal surface and can cause full-thickness perforation. Think of it like pushing a sock back out of a sleeve: you push from the end that went in last (the most distal point), not pull from the open end.
| Outcome | Detail |
|---|---|
| Mortality | < 1% in developed settings with timely intervention; rises significantly (up to 10–30%) if gangrenous/strangulated bowel [9] |
| Morbidity | Wound infection (~3–5%), anastomotic leak (rare in children), adhesive SBO in future (long-term risk of any laparotomy), short bowel syndrome (only if extensive resection required — very rare) |
| Recurrence after surgical reduction | ~1–4% (lower than non-operative reduction, ~5–10%) |
Regardless of whether reduction was non-operative or surgical, the child requires a period of close observation [7]:
| Component | Detail | Rationale |
|---|---|---|
| Hospital observation for 12–24 hours (post non-operative reduction) [7] | Monitor vitals, abdominal examination, and stool output frequently | Watch for recurrence (most common in first 72 hours) and complications |
| NG suction maintained until bowel function returns [7] | Continue NG decompression until passage of flatus or stool | Bowel function may take hours to normalise; premature feeding risks vomiting and aspiration |
| IV fluids | Continue maintenance IV fluids (e.g. 0.9% NaCl + 5% dextrose with 10–20 mmol/L KCl, at maintenance rate using Holliday-Segar formula) | Maintain hydration until oral intake re-established |
| Gradual reintroduction of feeds | Start with clear fluids once NG output decreases and bowel sounds return; advance to milk/formula/age-appropriate diet as tolerated | Ensure bowel function has recovered before challenging the gut |
| Fever post-reduction [7] | Patient usually presents with fever after successful reduction due to bacterial translocation or release of endotoxin or cytokines [7] | This is expected and does not necessarily indicate a complication. However, persistent or high fever should prompt re-evaluation (sepsis workup, repeat imaging) |
| Watch for recurrence | ~5–10% recurrence rate after non-operative reduction [3]; most occur within 72 hours; child and family should be counselled to return immediately if symptoms recur | Most recurrences can be treated with repeat enema reduction. ≥ 3 recurrences → surgical exploration for lead point |
| Discharge criteria | Tolerating full oral feeds, pain-free, afebrile, passing normal stools, parents counselled on recurrence signs | Safe discharge only when clinical recovery is confirmed |
Phase 5: Special Scenarios
- First recurrence: Repeat non-operative enema reduction is appropriate (success rate similar to first attempt).
- Second recurrence: Consider repeat enema but discuss with paediatric surgery.
- Third or more recurrences: Strongly consider surgical exploration to identify and resect a pathological lead point. Investigations before surgery may include CT abdomen with contrast to characterise the lead point.
- More common in HSP, post-operative, neonates, and older children with lead points [2].
- Less likely to respond to non-operative reduction (because the enema pressure is applied through the rectum and cannot easily reach a small bowel intussusception proximal to the ICV) [2].
- More likely to resolve spontaneously (the intussusception may self-reduce as peristalsis normalises) [2].
- Management: observation initially; surgical reduction if symptoms persist or worsen.
- Usually ileo-ileal; caused by submucosal haemorrhage and oedema.
- Non-operative reduction less effective for ileo-ileal type.
- Treatment of the underlying HSP (supportive ± steroids for severe abdominal pain) may allow spontaneous resolution.
- Surgical reduction if persistent or complicated.
| Stage | What to Communicate |
|---|---|
| At diagnosis | "Part of your child's bowel has folded inside itself, like a telescope. This is blocking the bowel and affecting its blood supply. We need to fix this urgently." |
| Before enema reduction | "We will gently inflate the bowel with air (or fill it with fluid) through the bottom to push the folded part back into place. This works in about 8 or 9 out of 10 children. There is a very small risk (less than 1 in 100) that the bowel could tear, and if that happens, we would need to proceed to surgery immediately." |
| If surgery needed | "The non-operative treatment was not successful / is not safe in your child's case. We need to do an operation to unfold the bowel. If any part of the bowel is damaged, we may need to remove that section. The surgeon will also look carefully for any underlying cause." |
| At discharge | "Your child has recovered well. However, there is about a 1 in 10 chance that this could happen again, usually within the next few days. If you notice severe crying, drawing up of legs, vomiting, or blood in the nappy, please bring your child back to the Emergency Department immediately." |
High Yield Summary — Management of Intussusception
- Resuscitate first: NPO, IV fluids (NS/Hartmann's 20 mL/kg bolus), NG decompression ("drip and suck"), analgesia, prophylactic IV antibiotics, correct electrolytes [7][10].
- Non-operative reduction is first-line: Pneumatic (air, fluoroscopic-guided) or hydrostatic (saline, USG-guided); 75–95% success rate [3].
- Pneumatic reduction technique: 18–22 Fr Foley catheter, maintain pressure ~100–120 mmHg for ~3 min per attempt, confirm success by gush of air into terminal ileum [3].
- Contraindications to enema reduction: Peritonitis, perforation, shock, suspected pathological lead point [3].
- Complications of enema reduction: Bowel perforation (< 1%), tension pneumoperitoneum (if pneumatic perforation), recurrence (~5–10%) [3][7].
- Surgical reduction indicated if: Failed enema, peritonitis/necrosis, perforation, suspected lead point, critically ill child [3][7].
- Surgical technique: Manual reduction by gentle retrograde compression (squeeze distally, do not pull); assess viability; resect if gangrenous; examine for lead point (run ileum 60 cm) [7][10].
- Post-reduction: Observe 12–24 hours; NG suction until bowel function returns; expect transient fever (bacterial translocation); watch for recurrence within 72 hours [7].
- Recurrence ≥ 3 times → surgical exploration for pathological lead point.
Active Recall - Management of Intussusception
References
[2] Senior notes: felixlai.md (Intussusception — Overview, Etiology) [3] Senior notes: maxim.md (Intussusception section) [4] Senior notes: Adrian Lui Pediatrics.pdf (p248–250, Intussusception, Meckel's diverticulum) [7] Senior notes: felixlai.md (Intussusception — Treatment section) [8] Senior notes: Ryan Ho Fundamentals.pdf (p279, Investigations for acute abdomen) [9] Senior notes: Ryan Ho GI.pdf (p134, Intussusception; p138–139, IO management) [10] Senior notes: felixlai.md (IO — Supportive management, Surgical treatment sections)
Complications of Intussusception in Children
The complications of intussusception arise from two interrelated processes:
- The disease process itself — progressive telescoping → mesenteric compromise → ischaemia → necrosis → perforation → peritonitis → sepsis → death.
- The treatment — both non-operative reduction and surgical intervention carry their own specific risks.
Every complication can be traced back to first principles if you understand the underlying pathophysiology: the intussusceptum drags its mesentery between two bowel walls → venous congestion → oedema → arterial compromise → ischaemia. The longer this process continues, the more complications accumulate. Time is bowel — early diagnosis and treatment dramatically reduce complication rates.
A. Complications of the Disease Process (Untreated or Delayed Diagnosis)
| Aspect | Detail |
|---|---|
| Mechanism | Telescoping drags the associated mesentery leading to venous and lymphatic congestion → intestinal oedema → ischaemia [4][7]. Initially, thin-walled mesenteric veins are compressed (low pressure, easily occluded). As oedema worsens, thicker-walled arteries are also compressed → complete transmural ischaemia → gangrenous bowel |
| Timeline | Risk increases significantly after 12–24 hours from symptom onset, though it can occur earlier in tight intussusception or children with vulnerable mesenteric perfusion |
| Clinical features | Constant (no longer colicky) severe abdominal pain; increasing abdominal distension and tenderness; peritoneal signs (guarding, rigidity, rebound); tachycardia; fever; metabolic acidosis with raised serum lactate [9][11] |
| Radiological signs | Pneumatosis intestinalis (intramural gas — gas produced by bacteria within the necrotic bowel wall); portal venous gas (gas tracking along mesenteric veins to the portal system); bowel wall thickening with reduced or lack of bowel wall enhancement on CT; engorgement of mesenteric vessels and oedematous, thickened mesentery [9][11] |
| Consequence | Gangrenous bowel cannot be salvaged → requires surgical resection with primary anastomosis. If extensive, may result in short bowel syndrome (see below) |
| Prognosis | Mortality: 2% (non-strangulated) vs 10–30% (strangulated) [9] — this stark difference underscores the importance of early diagnosis |
Why Does Venous Obstruction Precede Arterial?
Veins have thinner walls, lower intraluminal pressure (~5–10 mmHg), and are more compressible than arteries (~80–120 mmHg systolic). When the mesentery is compressed between the two bowel layers, the veins collapse first while the arteries continue to pump blood in. This creates a "vascular trap" — blood enters via the artery but cannot leave via the vein → venous engorgement → mucosal oedema → eventually the swelling compresses the arteries too → complete ischaemia.
| Aspect | Detail |
|---|---|
| Mechanism | Transmural necrosis weakens the bowel wall → the intraluminal pressure (from gas and fluid accumulating proximally to the obstruction) exceeds the wall's structural integrity → perforation at the site of maximum ischaemia (usually the apex of the intussusceptum or the point of maximum mesenteric compression) |
| Clinical features | Sudden worsening of pain → followed by transient relief (as intraluminal pressure drops); then rapid deterioration with generalised peritonitis, rigid abdomen, absent bowel sounds, septic shock |
| Radiological signs | Pneumoperitoneum — free gas under the diaphragm on erect CXR; Rigler's (double-wall) sign on supine AXR (gas visible on both sides of the bowel wall) [9][11] |
| Consequence | Faecal peritonitis → requires emergency laparotomy for washout, bowel resection, and primary anastomosis (or stoma in severely contaminated cases) |
| Aspect | Detail |
|---|---|
| Mechanism | Perforation allows bowel contents (bacteria, faecal matter, digestive enzymes) to spill into the peritoneal cavity → intense inflammatory response → generalised peritonitis. Even without overt perforation, bacterial translocation across ischaemic, compromised bowel wall can cause localised peritoneal inflammation |
| Clinical features | Peritoneal signs: fever, tachycardia, generalised abdominal tenderness, guarding, rigidity, rebound tenderness [11]; absent bowel sounds; the child lies very still (movement worsens pain) |
| Why it matters | Peritonitis is an absolute contraindication to non-operative enema reduction [3] — the bowel is too compromised, and insufflating air or fluid would worsen perforation/contamination. These children need emergency surgery |
| Aspect | Detail |
|---|---|
| Mechanism | Bacterial translocation across ischaemic bowel wall → bacteraemia → systemic inflammatory response → sepsis. If perforation has occurred → massive faecal contamination → overwhelming sepsis. Common organisms: gram-negative enterics (E. coli, Klebsiella), anaerobes (Bacteroides fragilis) |
| Clinical features | Fever or hypothermia; tachycardia; tachypnoea; poor peripheral perfusion (prolonged capillary refill > 3 seconds); altered mental status (lethargy, irritability); hypotension (late sign in children — children compensate well until they "crash") |
| Paediatric consideration | Children can maintain blood pressure through tachycardia and peripheral vasoconstriction until very late → hypotension in a child is a pre-arrest sign. Look for the early signs: tachycardia, poor perfusion, altered consciousness |
| Management | Aggressive IV fluid resuscitation (NS/Hartmann's 20 mL/kg bolus, repeat up to 3 times if needed); broad-spectrum IV antibiotics; emergency surgical source control |
| Aspect | Detail |
|---|---|
| Mechanism | Pooling of fluid in gut → hypovolaemic shock [4]. Multiple mechanisms contribute: (a) vomiting → external fluid loss; (b) third-spacing → fluid sequestered into oedematous bowel wall and peritoneal cavity (non-functional extracellular fluid); (c) poor oral intake; (d) if significant LGIB → haemorrhagic component |
| Clinical features | Tachycardia, cool extremities, weak peripheral pulses, prolonged capillary refill, reduced urine output (< 1 mL/kg/hr), sunken fontanelle (in infants), dry mucous membranes |
| Key point | Hypovolaemic shock can develop before sepsis in intussusception — it is a direct consequence of fluid losses from obstruction and vomiting. Always resuscitate aggressively before any intervention |
| Aspect | Detail |
|---|---|
| Mechanism | Vomiting → loss of gastric H⁺ and Cl⁻ → hypochloraemic, hypokalaemic metabolic alkalosis. Conversely, if bowel ischaemia develops → lactic acidosis superimposed. Third-spacing and poor intake worsen overall dehydration |
| Paediatric vulnerability | Infants have higher body-surface-area-to-weight ratio → proportionally greater insensible fluid losses. Lower glycogen reserves → risk of hypoglycaemia with fasting. Immature renal concentrating ability → less able to compensate for fluid losses |
| Assessment | Weight loss (% dehydration), skin turgor, fontanelle, mucous membranes, urine output, serum electrolytes, blood gas |
B. Complications of Non-Operative Reduction (Enema)
| Aspect | Detail |
|---|---|
| Incidence | < 1% for pneumatic reduction [7]; ~0.5–2.5% overall (slightly higher for hydrostatic with barium) |
| Mechanism | The enema pressure exceeds the structural integrity of the oedematous, potentially ischaemic bowel wall → perforation at the point of maximum weakness |
| Risk factors | Age < 6 months, long duration of symptoms, and higher pressure during reduction [7] |
| Consequences | Pneumatic perforation → tension pneumoperitoneum [3] — air escapes into the peritoneal cavity under pressure → abdominal distension → diaphragmatic splinting → respiratory compromise → compression of IVC → cardiovascular collapse. This is a life-threatening emergency requiring immediate needle decompression (14–16G needle in LUQ, midclavicular line) followed by emergency laparotomy. Hydrostatic perforation → fluid peritonitis (less acutely life-threatening than tension pneumoperitoneum but still requires emergency surgery). Barium perforation → barium peritonitis (catastrophic chemical peritonitis with very high mortality — this is why barium is largely avoided in modern practice) |
Tension Pneumoperitoneum — A True Emergency
Tension pneumoperitoneum is the most feared acute complication of pneumatic reduction [3]. Free air under pressure in the peritoneal cavity acts like a tension pneumothorax but in the abdomen — it compresses the diaphragm (impairs ventilation) and the IVC (impairs venous return → cardiovascular collapse).
Immediate management:
- Recognise: sudden deterioration during pneumatic reduction, abdominal distension, haemodynamic collapse
- Needle decompression: Insert 14–16G cannula in the left upper quadrant, midclavicular line to release the trapped air
- Emergency laparotomy for bowel repair/resection and peritoneal washout
| Aspect | Detail |
|---|---|
| Incidence | ~5% (some series up to 10%) [3] |
| Timing | Most recurrences occur within 72 hours of initial reduction; a second peak may occur within 6 months |
| Mechanism | Residual bowel inflammation which may itself act as a pathological lead point [7] — the oedematous, recently reduced ileum remains swollen → peristalsis catches it again → re-telescoping. Alternatively, the original trigger (e.g. viral Peyer's patch hypertrophy) persists |
| Management | First and second recurrences → repeat non-operative enema reduction (success rate similar to initial attempt). ≥ 3 recurrences → surgical exploration to identify and resect a pathological lead point |
| Key point | Recurrent intussusception beyond the typical age group or ≥ 3 episodes should prompt investigation for a structural lead point (Meckel's diverticulum, polyp, lymphoma, duplication cyst) [4][9] |
| Aspect | Detail |
|---|---|
| Incidence | Common — many children develop a low-grade fever in the hours after successful reduction |
| Mechanism | Bacterial translocation or release of endotoxin or cytokines [7] — the ischaemic, congested bowel wall has a compromised mucosal barrier. When the intussusception is reduced and perfusion restored (reperfusion), bacteria and endotoxins that had translocated across the damaged mucosa are released into the systemic circulation, triggering a transient febrile response |
| Management | Usually self-limiting; prophylactic antibiotics given pre-procedure help mitigate this. Persistent or high-grade fever (> 38.5°C for > 24 hours) warrants re-evaluation: repeat USG (to exclude recurrence), blood cultures, and clinical reassessment |
| Aspect | Detail |
|---|---|
| Mechanism | The intussusception appears to reduce on fluoroscopy/USG, but a small residual "nubbin" of oedematous ileum remains at the ileocaecal valve, which may serve as a nidus for re-intussusception |
| How to avoid | Confirm complete reduction by visualising free flow of air/contrast into the terminal ileum; post-reduction USG to ensure no residual intussusception |
| Complication | Mechanism | Incidence | Notes |
|---|---|---|---|
| Wound infection | Contamination of surgical wound by bowel flora, especially if perforation was present | ~3–5% | Standard wound care; IV antibiotics peri-operatively |
| Anastomotic leak | Failure of the bowel anastomosis to heal → leakage of intestinal contents into peritoneal cavity → peritonitis | Rare in children (< 2%) | Children generally have excellent healing capacity; risk increases if anastomosis performed on oedematous or ischaemic bowel margins |
| Adhesive small bowel obstruction | Any laparotomy causes intra-abdominal adhesions (fibrous bands) as part of the healing process → adhesions can kink or compress bowel loops → mechanical SBO | Long-term risk ~5% | Can present months to years after the original surgery. This is the most common cause of SBO in any patient with prior abdominal surgery |
| Short bowel syndrome | If extensive bowel resection is required (e.g. long gangrenous segment) → insufficient remaining bowel length for adequate nutrient absorption → malabsorption, failure to thrive | Very rare | More likely if > 50% of small bowel is resected. In neonates/infants, the minimum viable length is ~40 cm of small bowel with the ileocaecal valve intact (or ~70 cm without ICV). Requires long-term parenteral nutrition support |
| Recurrence after surgical reduction | Lower than non-operative reduction (~1–4%) because the surgeon directly reduces the intussusception and can address any lead point | ~1–4% | Still possible if a small lead point was missed or if no lead point was present (idiopathic) |
| Stoma-related complications | If a stoma was created (rare in children; only if very contaminated field or tenuous anastomosis): stomal prolapse, retraction, parastomal hernia, high-output stoma with dehydration/electrolyte loss | Uncommon | Paediatric stoma care requires specialist nursing input and family education |
If a pathological lead point was the cause of the intussusception and was not identified/treated, it will continue to cause problems:
| Lead Point | Complications if Missed |
|---|---|
| Meckel's diverticulum | Recurrent intussusception; recurrent GI bleeding (from ectopic gastric mucosa); Meckel's diverticulitis (mimics appendicitis); volvulus around fibrous band [5] |
| Lymphoma (Burkitt) | Progressive tumour growth → recurrent intussusception, bowel obstruction, perforation; systemic dissemination if not diagnosed and treated with chemotherapy |
| Polyps | Recurrent intussusception; ongoing LGIB; risk of malignant transformation in certain polyposis syndromes (e.g. FAP, Peutz-Jeghers) |
| Duplication cyst | Recurrent intussusception; GI bleeding (if contains ectopic gastric mucosa); volvulus; infection |
| Timeline | Complication |
|---|---|
| During the disease (untreated) | Bowel ischaemia → necrosis → perforation → peritonitis → sepsis → shock → death |
| During non-operative reduction | Bowel perforation (< 1%); tension pneumoperitoneum (pneumatic) [3] |
| Hours after reduction | Post-reduction fever (bacterial translocation); incomplete reduction |
| Days after reduction | Recurrence (~5–10%) [3]; wound infection (post-surgical) |
| Weeks to months | Recurrence (late); adhesive SBO (post-surgical) |
| Long-term | Short bowel syndrome (if extensive resection); adhesive SBO; complications of missed lead point |
| Scenario | Outcome |
|---|---|
| Early presentation + successful non-operative reduction | Excellent prognosis; near-zero mortality; full recovery expected |
| Early presentation + surgical reduction (viable bowel) | Very good prognosis; mortality < 1% |
| Delayed presentation with gangrenous bowel | Mortality rises to 10–30% [9]; morbidity significantly higher |
| Perforation with faecal peritonitis and sepsis | Highest mortality; multiple complications including organ failure |
The single most important prognostic factor is time to diagnosis and treatment. In Hong Kong, maintaining a high index of suspicion in any infant 6–36 months with acute abdominal symptoms and obtaining urgent USG leads to early diagnosis and excellent outcomes.
High Yield Summary — Complications of Intussusception
- Disease complications follow a cascade: ischaemia → necrosis → perforation → peritonitis → sepsis → shock → death. Mortality: 2% (non-strangulated) vs 10–30% (strangulated) [9].
- Venous obstruction precedes arterial — veins are low-pressure and compress first → "vascular trap" → congestion → mucosal ooze (currant jelly stool) → then arterial compromise → gangrene.
- Hypovolaemic shock from fluid pooling in the gut, vomiting, and third-spacing can develop before sepsis [4].
- Non-operative reduction complications: Perforation (< 1%), risk factors: age < 6 months, prolonged symptoms, high pressure [7]. Pneumatic perforation → tension pneumoperitoneum → needle decompression → emergency laparotomy [3].
- Recurrence: ~5–10% after non-operative reduction [3]; most within 72 hours. ≥ 3 recurrences → surgical exploration for pathological lead point.
- Post-reduction fever is expected (bacterial translocation) and usually self-limiting [7].
- Surgical complications: Wound infection, anastomotic leak (rare in children), adhesive SBO (long-term), short bowel syndrome (very rare, only if extensive resection).
- Always look for and address the underlying lead point — if missed, the lead point will cause recurrence and its own disease-specific complications.
- Key paediatric vulnerabilities: Higher radiation sensitivity, higher surface-area-to-weight ratio (faster dehydration), lower glycogen reserves (hypoglycaemia risk), immature renal function, difficulty verbalising symptoms.
Active Recall - Complications of Intussusception
References
[3] Senior notes: maxim.md (Intussusception section) [4] Senior notes: Adrian Lui Pediatrics.pdf (p248, Intussusception) [5] Senior notes: maxim.md (Meckel diverticulum section) [7] Senior notes: felixlai.md (Intussusception — Treatment, Complications) [9] Senior notes: Ryan Ho GI.pdf (p134, Intussusception; p137, IO complications; p139, IO surgical Mx and prognosis) [11] Senior notes: felixlai.md (IO — Complications: Strangulation, CT findings of complicated IO)
Coarctation Of The Aorta
Coarctation of the aorta is a congenital narrowing of the aorta, typically near the ductus arteriosus, presenting in neonates with heart failure or in older children and adolescents with upper extremity hypertension, diminished femoral pulses, and a blood pressure gradient between the arms and legs.
Noisy Breathing / Snoring
Noisy breathing or snoring in children is turbulent airflow through a partially obstructed upper airway during sleep, most commonly caused by adenotonsillar hypertrophy, and may indicate obstructive sleep-disordered breathing requiring further evaluation.