Hernia

1. Definition

Hernia: the protrusion of an organ (or part of an organ) through the wall of its containing cavity ^[1][2][3].

Break down the word: "hernia" derives from Latin hernios = rupture/protrusion. The concept is simple — something that should stay inside pushes through a weak spot in the wall that normally contains it. Think of it like an inner tube bulging through a weak spot in a tyre.

Three essential components of every hernia:

1. Hernia sac — the outpouching of peritoneum (or its equivalent) that lines the defect
2. Hernia contents — the organ/tissue that enters the sac (omentum, small bowel, colon, bladder, etc.)
3. Hernia neck/ring — the aperture through which the sac protrudes; its diameter determines the risk of complications (narrow neck → higher strangulation risk)

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2. Epidemiology

2.1 Frequency & Distribution

• Inguinal hernias are the most common type, accounting for ~78% of all abdominal wall hernias ^[2][3].
• Incisional hernias are the second most common type overall ^[2].
• Femoral hernias account for only 2–8% of all adult groin hernias ^[1].
• Indirect inguinal hernia is the MOST common groin hernia in both sexes ^[3][4].

2.2 Age Distribution

• Median age of diagnosis in males: 50–69 years ^[4]
• Median age of diagnosis in females: 60–79 years ^[4]
• Inguinal hernias have a bimodal distribution:
  • Peak 1 — Infancy/early childhood (congenital indirect inguinal hernia from patent processus vaginalis)
  • Peak 2 — Middle-aged to elderly adults (acquired weakness of transversalis fascia)
• Femoral hernia occurs later in life than inguinal hernia ^[4]

2.3 Sex Distribution

• Hernias are generally more common in males ^[4]
  • Male-to-female ratio for inguinal hernias is approximately 8–10 : 1
  • Why? — The deep inguinal ring is wider in males (to accommodate the spermatic cord) compared to the smaller opening for the round ligament in females
  • Deep inguinal ring is narrower in women, hence a lower incidence of indirect inguinal hernia ^[4]
• Femoral hernia is more common in females ^[1][4]
  • Related to the wider pelvis (wider femoral canal) and comparatively less muscle bulk / weakening of musculature from childbirth ^[2][4]
  • However, even in females, inguinal hernia is still more common than femoral hernia ^[4]

2.4 Laterality

• Right-sided inguinal hernias are more common ^[4]
  • Why? — Related to later descent of the right testicle and later obliteration of the processus vaginalis on the right ^[4]

2.5 Complication Rates

• Femoral hernias present with more complications such as incarceration and strangulation than inguinal hernias ^[4]
  • Strangulation risk: Femoral > Indirect inguinal > Direct inguinal ^[2]
  • This directly correlates with neck width: femoral ring is the tightest → highest strangulation risk

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3. Risk Factors

Risk factors can be understood through one unifying framework: hernia = (defect in wall integrity) + (forces pushing contents through). Thus, anything that weakens the wall or increases intra-abdominal pressure (IAP) predisposes.

3.1 Non-Modifiable (Intrinsic) Risk Factors [1][3][4]

3.2 Modifiable (Acquired) Risk Factors [1][3][4]

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4. Anatomy

Understanding hernia anatomy from first principles is non-negotiable — the anatomy determines the type of hernia, the surgical approach, and the risk of complications.

4.1 Layers of the Anterior Abdominal Wall (Superficial → Deep) [2][3]

1. Skin
2. Camper's fascia (superficial fatty layer of superficial fascia)
3. Scarpa's fascia (deep membranous layer of superficial fascia) — continuous with Colles' fascia in the perineum and dartos fascia in the scrotum
4. External oblique (EO) muscle and its aponeurosis
5. Internal oblique (IO) muscle and its aponeurosis
6. Transversus abdominis (TA) muscle and its aponeurosis
7. Transversalis fascia — the critical layer; weakness here allows direct inguinal hernias
8. Extra-peritoneal (pre-peritoneal) fat
9. Parietal peritoneum

4.2 Rectus Sheath [2]

The rectus sheath is formed by the interlacing aponeuroses of EO, IO, and TA:

• Above the arcuate line (approximately 5 cm below umbilicus, at one-third the distance from umbilicus to pubic crest):
  • Anterior sheath: EO aponeurosis + anterior leaf of IO aponeurosis
  • Posterior sheath: posterior leaf of IO aponeurosis + TA aponeurosis
  • Rectus abdominis is fully enclosed
• Below the arcuate line:
  • Anterior sheath: ALL three aponeuroses pass anteriorly
  • Posterior: only transversalis fascia (and peritoneum) — no muscular/aponeurotic posterior sheath
  • This is why the lower abdomen is relatively weaker and why Spigelian hernias and incisional hernias of lower midline incisions are common here

Contents of rectus sheath: rectus abdominis, pyramidalis, superior and inferior epigastric vessels, thoraco-abdominal nerves (T7–T11), subcostal nerve (T12) ^[2].

4.3 The Inguinal Canal [1][2][3]

The inguinal canal is an oblique passage (~4 cm long) through the lower anterior abdominal wall, running inferomedially from the deep inguinal ring to the superficial inguinal ring.

Contents:

• Male: spermatic cord + ilioinguinal nerve
• Female: round ligament of the uterus + ilioinguinal nerve

Walls of the Inguinal Canal ^[2]:

Deep Inguinal Ring ^[2]:

• An opening in the transversalis fascia
• Located 1 cm above the midpoint of the inguinal ligament (midpoint between ASIS and pubic tubercle)
• Lateral to the inferior epigastric vessels — this is the key landmark distinguishing indirect from direct hernias

Superficial Inguinal Ring ^[2]:

• A triangular defect in the external oblique aponeurosis
• Located just superolateral to the pubic tubercle

Landmark tip:

• Mid-point of inguinal ligament (PT to ASIS) → deep inguinal ring is 1 cm above
• Mid-inguinal point (pubic symphysis to ASIS) → femoral artery pulse

4.4 Myopectineal Orifice of Fruchaud (MPO) [1]

First described by Dr. Henri Fruchaud in 1956 ^[1]. This is the conceptual unifying anatomical framework for all groin hernias.

• An area of weakness in the pelvic region ^[1]
• Normal congenital/anatomical gaps occur in this area ^[1]
• Not reinforced by muscle layers like the rest of the abdominal wall ^[1]
• More prone to repetitive increases in intra-abdominal pressure leading to progressive bulging, weakness, and hernia formation ^[1]
• The MPO is a single large orifice divided by the inguinal ligament into:
  • Superior compartment → inguinal hernias (direct and indirect)
  • Inferior compartment → femoral hernias
• Bounded by: rectus abdominis (medially), iliopsoas (laterally), pubic bone/Cooper's ligament (inferiorly), and the conjoined aponeurotic arch (superiorly)

4.5 Hesselbach's Triangle [2][3][4]

The anatomical region through which direct inguinal hernias protrude:

The floor of Hesselbach's triangle is the transversalis fascia covered by the external oblique aponeurosis. Direct hernias push through the weakened transversalis fascia in this region.

4.6 The Spermatic Cord [2]

The spermatic cord runs from the deep inguinal ring to the testis. Its three fascial coverings are derived from the layers of the abdominal wall that the processus vaginalis traverses during testicular descent:

Note: Transversus abdominis (TA) does NOT contribute a fascial layer to the spermatic cord ^[2].

Contents of the Spermatic Cord — "3-3-3 rule" ^[2]:

4.7 Anatomy of the Femoral Canal [1][2]

The femoral canal is the medial-most compartment of the femoral sheath. Femoral hernias protrude through the femoral ring into the femoral canal ^[3][4].

Femoral Triangle (boundaries) ^[2]:

• Superior: inguinal ligament
• Medial: adductor longus
• Lateral: sartorius
• Contents: NAVEL — Femoral Nerve, Femoral Artery, Femoral Vein, Empty space (femoral canal), Lymph nodes

Femoral Canal Boundaries (posterior/internal view) ^[2][3][4]:

• The femoral canal contains the deep inguinal lymph node of Cloquet which drains the penis/clitoris ^[2]
• The femoral ring is small and rigid (surrounded by ligaments and the femoral vein) — this is why femoral hernias have a high risk of strangulation ^[1][3]

4.8 Processus Vaginalis — The Embryological Foundation [3][4]

Understanding the processus vaginalis (PV) is essential because it explains indirect inguinal hernias, hydroceles, and encysted hydroceles of the cord.

Developmental Sequence:

1. During fetal development (months 7–9), the testes descend from the retroperitoneum through the inguinal canal into the scrotum, guided by the gubernaculum
2. A finger-like evagination of peritoneum — the processus vaginalis — precedes the testis through the inguinal canal
3. The PV normally obliterates (closes) after birth
4. The distal remnant becomes the tunica vaginalis surrounding the testis

In females: The equivalent structure is the canal of Nuck, which accompanies the round ligament through the inguinal canal. If it persists, it produces a hydrocele of the canal of Nuck or an indirect inguinal hernia.

Timing of closure ^[4]:

• Within 2 months: closes in ~40% of neonates
• Within 2 years: additional ~20% close
• Of the remaining ~40% with a patent PV, approximately half (i.e., ~20% overall) develop a clinical hernia

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5. Etiology & Pathophysiology

5.1 Natural Causes of Hernia [4]

Hernias occur at sites of pre-existing anatomical weakness:

A. Natural weakness:

• Lumbar triangles (superior triangle of Grynfeltt-Lesshaft, inferior triangle of Petit)
• Posterior wall of the inguinal canal (Hesselbach's triangle — transversalis fascia)
• Umbilicus (where the abdominal wall never fully muscularises)

B. Weakness due to structures entering and leaving the abdomen:

• Oesophagus through diaphragm → hiatus hernia
• Femoral vessels through femoral ring → femoral hernia
• Spermatic cord/round ligament through inguinal canal → inguinal hernia
• Obturator nerve through obturator foramen → obturator hernia
• Sciatic nerve through sciatic foramen → sciatic hernia

5.2 Congenital Hernia [3][4]

Congenital hernia is due to failure of processus vaginalis to close (patent processus vaginalis) ^[4].

Pathophysiology:

• A patent PV acts as a pre-formed sac
• Increases in IAP (crying, straining) force abdominal contents (usually bowel or omentum) into this sac
• In males: hernia descends alongside the spermatic cord, potentially reaching the scrotum (complete indirect inguinal hernia)
• In females: hernia descends along the round ligament through the canal of Nuck
• Congenital inguinal hernias are almost always indirect

Why are they more common on the right? — Because the right testis descends later in fetal development, and therefore the right processus vaginalis obliterates later, providing a longer window of vulnerability ^[4].

5.3 Acquired Hernia [3][4]

Defect develops as a result of weakening or disruption of fibromuscular tissues of the abdominal wall ^[4].

Two broad mechanisms:

A. Primary tissue degeneration (for direct inguinal and other abdominal wall hernias):

• Ageing → loss of collagen cross-linking, sarcopenia → transversalis fascia stretches and attenuates
• Abnormal collagen metabolism → altered type I:III collagen ratio (type III is mechanically weaker); elevated matrix metalloproteinase (MMP) activity
• Smoking → reduces prolyl hydroxylase activity (needed for collagen synthesis) and increases serine protease activity → net collagen degradation

B. Disruption of wall integrity (for incisional hernias):

• Surgical incision disrupts fascial continuity
• Impaired wound healing (infection, malnutrition, immunosuppression, obesity, smoking, excessive wound tension, use of steroids/chemotherapy) → the scar never regains full strength
• Emergency surgery and prolonged operative time increase risk

C. Raised IAP as a precipitant:

• Chronic cough (COPD), chronic constipation, BPH (straining to void), heavy lifting, obesity, pregnancy, ascites
• Acts on a pre-existing weakness to force peritoneum and contents through

5.4 Pathophysiology of Hernia Complications

The sequential pathophysiology of a hernia that progresses from reducible to gangrenous:

Step-by-step mechanism of strangulation:

1. Bowel enters a tight hernia sac through a narrow neck
2. The narrow neck compresses the thin-walled veins first (venous return is impeded before arterial inflow because venous pressure is lower)
3. Venous congestion → oedema of bowel wall → bowel swells further → now cannot reduce
4. Rising tissue pressure eventually occludes arterioles → ischaemia
5. Mucosal barrier fails → bacterial translocation → toxins enter the peritoneum and bloodstream
6. Full-thickness necrosis (gangrene) → perforation → faecal peritonitis → sepsis → death if untreated

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6. Classification

6.1 By Region [3][4]

6.2 By Etiology [4]

• Congenital — defect present from birth (patent PV → indirect inguinal hernia; umbilical ring defect)
• Acquired — develops from weakening/disruption (direct inguinal, incisional, femoral in adults)

6.3 By Reducibility (Descriptive Terminology) [2][3][4]

6.4 Special Types [1][2][3]

6.5 Inguinal Hernia Sub-classification [1][2][3][4]

Deep Ring Occlusion Test: After reducing the hernia, place your thumb over the deep inguinal ring (1 cm above the midpoint of the inguinal ligament). Ask the patient to cough:

• If the hernia is controlled (does not reappear) → indirect (you have blocked its route through the deep ring)
• If the hernia is not controlled (reappears medially) → direct (it enters through Hesselbach's triangle, not the deep ring)

6.6 Different Types of Ventral Hernia [2][3][4]

Umbilical vs. Paraumbilical Hernia:

• Pathophysiology: occurs due to stretching and thinning of the linea alba ^[4]
• Acquired causes: increased IAP (obesity, pregnancy, chronic cough, constipation, ascites)
• Small hernias contain extraperitoneal fat/omentum; large hernias may contain small or large bowel with high risk of incarceration and strangulation ^[4]

Epigastric hernia: defects in the midline between umbilicus and xiphoid process through the linea alba aponeurotic intersections; usually contain only pre-peritoneal fat (not bowel); occur in middle-aged men after lifting ^[2][3]

Spigelian hernia: passes through the semilunar line (lateral border of rectus sheath), which is the caudal-most extent of the posterior rectus sheath; often interparietal (between muscle layers) and difficult to diagnose clinically ^[3]

Diastasis recti (divarication of recti): linea alba stretches laterally due to overweight or pregnancy; exacerbated by looking at toes (head raise); this is NOT a true hernia (no fascial defect, no hernia sac) — simply a widening of the gap between the two rectus muscles. No risk of incarceration. No surgical repair needed unless symptomatic/cosmetic ^[2].

Incisional hernia ^[2][3][4]:

• Hernia developing at sites where an incision has been made = partial wound dehiscence (skin remains intact)
• Essentially an extrusion of abdominal content through a weak scar
• Risk factors: patient factors (age, obesity, immunocompromised), local factors (infection, haematoma, chemo/RT), surgeon factors (poor surgical technique with tension, placing drains through wounds, emergency/prolonged OT) ^[2]
• Physical examination: define fascial defect by tilting head up to look at toes (contracts rectus, accentuates defect) ^[2]
• Complications: intermittent obstruction, incarceration/strangulation, enterocutaneous fistula (skin excoriation)

Parastomal hernia: a subtype of incisional hernia occurring adjacent to a stoma site (very common, up to 50% of colostomies)

Lumbar hernia ^[3]:

• Occurs in the region bounded: superiorly by 12th rib, inferiorly by iliac crest, medially by erector spinae, laterally by internal oblique
• Through either the superior (Grynfeltt-Lesshaft) or inferior (Petit) lumbar triangle

Obturator hernia ^[3]:

• Passes through the obturator foramen alongside the obturator nerve
• Classic presentation: elderly thin woman with intestinal obstruction and positive Howship-Romberg sign (pain along the medial thigh on internal rotation of the hip — due to obturator nerve compression)

Sciatic hernia ^[3]:

• Extremely rare; passes through greater or lesser sciatic foramen

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7. Clinical Features

7.1 Symptoms

In paediatric patients (neonates/infants) ^[5][6]:

• Intermittent groin swelling during crying or straining is the classical presentation
• Parents may notice a bulge that comes and goes
• Irritability, poor feeding, and inconsolable crying may signal incarceration
• Incarcerated inguinal hernia is a surgical emergency in children — higher risk of gonadal compromise (testicular ischaemia in boys, ovarian torsion in girls)

7.2 Signs

General Examination of a Groin Lump:

Distinguishing Features — Inguinal vs. Femoral Hernia (Physical Examination):

Examination of Associated Features ^[2]: Always examine for underlying causes and contributing factors:

• Abdomen: ascites, organomegaly, abdominal masses (e.g., ovarian mass raising IAP)
• Chest: signs of COPD (barrel chest, hyperresonance) — chronic cough as precipitant
• Digital rectal examination: prostatic enlargement (BPH → straining to void)
• Contralateral groin: bilateral hernias are common, especially in direct type
• Both testes: check for undescended testis (differential), testicular atrophy (post-previous repair)

7.3 Clinical Features Specific to Hernia Complications

7.4 Paediatric Specific Clinical Features [5][6]

Inguinal hernia in children:

• Almost exclusively indirect (patent processus vaginalis)
• More common in premature infants (PV has had less time to obliterate)
• Male:Female ratio approximately 6:1
• 60% right-sided, 30% left-sided, 10% bilateral
• Presents as intermittent inguinal/scrotal swelling during crying, straining, or Valsalva
• Incarceration rate is highest in the first year of life (~30% in infants < 6 months)
• In girls, the ovary (± fallopian tube) may herniate — palpable as a firm, non-tender, mobile nodule in the labia/groin (ovary in the sac)

Umbilical hernia in children:

• Defect in the umbilical ring present from birth
• Very common in African descent infants (up to 25–30%)
• Most close spontaneously by age 3–5 years — therefore observation is appropriate
• Surgery indicated if: (1) persists beyond age 4–5, (2) defect > 1.5–2 cm (unlikely to close), (3) symptomatic, (4) incarceration (rare in children)
• Rarely strangulates in children (the neck is usually broad)

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8. Differential Diagnosis of a Groin Mass [4]

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9. Key Anatomical and Clinical Differences — Summary Table

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Active Recall - Hernia (Definition to Clinical Features)

1. What are the boundaries of Hesselbach's triangle, and which type of inguinal hernia passes through it?

Your answer

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Inferior: inguinal ligament. Lateral: inferior epigastric vessels. Medial: lateral border of rectus sheath. Direct inguinal hernia protrudes through this triangle due to weak transversalis fascia.

2. Name the boundaries of the femoral canal (ring). Why do femoral hernias have a high strangulation risk?

Your answer

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Anterior: inguinal ligament. Posterior: pectineal (Cooper's) ligament. Medial: lacunar ligament. Lateral: femoral vein. The ring is small and rigid (bound by ligaments/vein) so contents are easily trapped.

3. What is a Richter's hernia and why is it dangerous?

Your answer

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Incarcerated hernia involving only one sidewall of the bowel. Causes ischaemia and potential perforation without causing complete intestinal obstruction, delaying diagnosis. Classically associated with femoral hernias.

4. Explain the deep ring occlusion test. How does it differentiate indirect from direct inguinal hernia?

Your answer

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After reducing the hernia, apply digital pressure over the deep inguinal ring (1 cm above midpoint of inguinal ligament). If hernia is controlled (does not reappear on coughing) it is indirect (enters via deep ring). If not controlled (reappears medially) it is direct (enters through Hesselbach's triangle).

5. List the intrinsic and acquired risk factors for inguinal hernia as per the lecture slides.

Your answer

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Intrinsic: (1) family history, (2) previous contralateral hernia, (3) gender (male), (4) age, (5) abnormal collagen metabolism. Acquired: (1) prostatectomy, (2) obesity, (3) chronic constipation, (4) pulmonary disease.

6. Describe the pathophysiological sequence from incarceration to gangrene in a strangulated hernia.

Your answer

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Narrow neck traps bowel, compresses thin-walled veins first (lower pressure), venous congestion leads to oedema, bowel swells and becomes further trapped, rising tissue pressure occludes arterioles, ischaemia ensues, mucosal barrier fails, bacterial translocation occurs, full-thickness necrosis (gangrene), perforation, peritonitis and sepsis.

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References

^[1] Lecture slides: GC 193. Inguinal and scrotal swelling different types of hernia.pdf ^[2] Senior notes: maxim.md (Chapter 6 — Hernia) ^[3] Senior notes: felixlai.md (Hernia section) ^[4] Senior notes: felixlai.md (Epidemiology, Etiology, Pathophysiology sections) ^[5] Lecture slides: GC 203. The child needs an operation Common emergencies and surgery in childhood.pdf ^[6] Lecture slides: Neonatal Surgery.pdf

Differential Diagnosis of Hernia

The differential diagnosis of hernia is fundamentally a question of anatomical location. You are not just asking "is this a hernia?" — you are asking "what else could produce a lump or pain in this region?" The approach differs depending on whether the presentation is a groin lump, a scrotal swelling, or abdominal pain where a hernia might be mimicked or missed.

Let's work through this systematically.

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1. Clinical Approach to Differential Diagnosis

The very first question when confronted with any lump in the inguinal or scrotal region is to determine its anatomical compartment. This dictates your entire differential:

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2. Differential Diagnosis of a Groin Lump

This is the primary differential when hernia is suspected. The lecture slides categorise groin lumps into painful and painless presentations ^[1]:

2.1 Painful Groin Lumps [1]

2.2 Painless Groin Lumps [1]

2.3 Full DDx of Groin Mass — L SHAPE Mnemonic [2]

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3. Differential Diagnosis of Scrotal Swelling

When the presentation is primarily a scrotal mass, the differential overlaps with hernia (because indirect inguinal hernias can descend into the scrotum). The lecture slides provide a clear division ^[1]:

3.1 Painful Scrotal Lumps [1]

3.2 Painless Scrotal Lumps [1]

3.3 Summary Comparison Table for Scrotal Lumps [3][4]

Typical history clues from the lecture slides ^[1]:

• "Reducible groin mass" → Hernia
• "Painful scrotal swelling" → Epididymo-orchitis / Torsion
• "Painless scrotal enlargement" → Hydrocele / Testicular tumour
• "Fullness / bag of worms" → Varicocele

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4. Differential Diagnosis of Abdominal Pain Where Hernia is in the Differential

Hernias (inguinal and femoral) frequently appear in the differential diagnosis of lower abdominal pain because a strangulated or obstructed hernia can present as an acute abdomen. The lecture slides emphasise this ^[5][6]:

4.1 Right Lower Quadrant (RLQ) Pain [5]

Inguinal/femoral hernia must be considered alongside:

• Acute appendicitis (the most common surgical emergency)
• Caecal diverticulitis
• Ureteric colic
• Ruptured ectopic pregnancy
• Mesenteric adenitis
• Torsion of ovarian cyst
• Ileitis (Crohn's, Yersinia)
• Meckel's diverticulitis
• Caecal ischaemia
• Cancer of caecum
• Testicular pathology (torsion, epididymo-orchitis)
• Perforated peptic ulcer (referred)
• Acute cholecystitis (referred)

4.2 Left Lower Quadrant (LLQ) Pain [6]

Inguinal/femoral hernia must also be considered here:

• Sigmoid diverticulitis
• Cancer of sigmoid colon
• Torsion of ovarian cyst
• Ruptured ectopic pregnancy
• Ureteric colic
• Testicular pathology

4.3 Diffuse / Non-specific Abdominal Pain [5]

In the lecture slide titled "Have You Forgotten?", hernias are specifically listed as a commonly overlooked diagnosis ^[5]:

"Hernia, inguinal or femoral" — Always examine the groin in any patient with abdominal pain, vomiting, or intestinal obstruction. A strangulated femoral hernia in an elderly woman can easily be missed if the groin is not examined.

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5. Differential Diagnosis Specific to Hernia Type

When you have already established that the patient likely has a hernia, the next step is determining what type and differentiating between them:

5.1 Inguinal vs Femoral Hernia

5.2 Direct vs Indirect Inguinal Hernia

5.3 Inguinal Hernia vs Communicating Hydrocele (Paediatric) [7]

This is a critical paediatric differential — both arise from a patent processus vaginalis:

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6. Comprehensive DDx by Anatomical Region — Master Table [1][2][3][5][6]

The lecture slides provide detailed region-by-region lists ^[1]:

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7. Paediatric-Specific Differentials [7]

In infants and children presenting with an inguinal/scrotal swelling, the differential is slightly different:

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Active Recall - Differential Diagnosis of Hernia

1. A 75-year-old woman presents with a small, firm, non-reducible lump below and lateral to the pubic tubercle with no cough impulse. She is vomiting and has not passed flatus for 12 hours. What is the most likely diagnosis and why is it dangerous?

Your answer

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Strangulated femoral hernia. Dangerous because the femoral ring is small and rigid (bounded by ligaments and femoral vein), giving a very tight neck that rapidly compresses venous return then arterial supply, leading to bowel ischaemia and gangrene. Often presents as Richter's hernia (only sidewall of bowel caught).

2. Name the L SHAPE mnemonic for the differential diagnosis of a groin lump and provide one distinguishing feature for each.

Your answer

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L = Lymph nodes (multiple, discrete, non-reducible, no cough impulse). S = Saphena varix (bluish, fluid thrill on cough, disappears on lying). H = Hernia (cough impulse, reducible). A = Aneurysm of femoral artery (expansile pulsation). P = Psoas abscess (fluctuant, hip held in flexion, associated with spinal TB). E = Ectopic/undescended testis (absent ipsilateral scrotal testis).

3. How do you differentiate between an indirect inguinal hernia and a communicating hydrocele in a child? What is their common embryological basis?

Your answer

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Both arise from a patent processus vaginalis. Hernia: contains bowel/omentum, does NOT transilluminate, has cough impulse, reduces quickly. Communicating hydrocele: contains only peritoneal fluid, transilluminates, no cough impulse, gradually empties when supine and enlarges over the day. Both are repaired by herniotomy (high ligation of PV).

4. List the typical history clues for each of the following scrotal pathologies as highlighted in the lecture slides: hernia, epididymo-orchitis/torsion, hydrocele/testicular tumour, varicocele.

Your answer

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Reducible groin mass = hernia. Painful scrotal swelling = epididymo-orchitis or torsion. Painless scrotal enlargement = hydrocele or testicular tumour. Fullness or bag of worms = varicocele.

5. Why must you always examine the groin in a patient with acute abdominal pain or intestinal obstruction?

Your answer

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A strangulated femoral or inguinal hernia can present as intestinal obstruction or acute abdomen. Femoral hernias in particular (small, below inguinal ligament, in obese elderly women) are easily missed if groins are not examined. The lecture slide explicitly warns: Have you forgotten? Hernia, inguinal or femoral.

References

^[1] Lecture slides: GC 193. Inguinal and scrotal swelling different types of hernia.pdf (p6, p7, p8, p25) ^[2] Senior notes: maxim.md (Chapter 6 — Hernia; DDx of groin lump — L SHAPE) ^[3] Senior notes: felixlai.md (Hernia — DDx of groin mass; Scrotal swelling tables) ^[4] Senior notes: felixlai.md (Comparison between hydrocele, varicocele and spermatocele) ^[5] Lecture slides: GC 195. Lower and diffuse abdominal pain RLQ problems; pelvic inflammatory disease; peritonitis and abdominal emergencies.pdf (p5, p44) ^[6] Lecture slides: GC 195. Lower and diffuse abdominal pain RLQ problems; pelvic inflammatory disease; peritonitis and abdominal emergencies.pdf (p6) ^[7] Lecture slides: GC 203. The child needs an operation Common emergencies and surgery in childhood.pdf

Diagnostic Criteria, Algorithm & Investigations for Hernia

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1. Diagnostic Criteria — Is It a Hernia?

Hernia is fundamentally a clinical diagnosis ^[1][2]. There are no formal "diagnostic criteria" in the way that, say, rheumatic fever has the Jones criteria. Instead, the diagnosis rests on recognising a constellation of clinical findings during a systematic physical examination. Think of it as a checklist of positive physical signs that, taken together, confirm the diagnosis and characterise the hernia.

1.1 The Clinical Diagnostic Triad

For a groin lump to be confidently called a hernia, you need to demonstrate:

1. An inguinoscrotal or groin lump that you cannot get above — this means the lump originates from, or extends into, the abdominal cavity/inguinal canal rather than being a purely scrotal or subcutaneous pathology
2. Cough impulse — an expansile impulse felt or seen on coughing, confirming communication between the lump and the peritoneal cavity via the defect (although femoral hernias commonly do NOT exhibit cough impulse due to the tight neck ^[3][4])
3. Reducibility — the ability to return contents into the abdomen (present in uncomplicated hernias; absent in irreducible/incarcerated/strangulated hernias)

When all three are present, the clinical diagnosis is essentially certain. When they are equivocal (e.g., intermittent symptoms with no demonstrable lump, or a small irreducible lump without cough impulse), imaging is needed.

1.2 Characterising the Hernia — Physical Examination Approach

Once you've established that a hernia exists, the physical examination classifies it:

Step 1 — Standing Inspection ^[3]:

• Position the patient standing with full exposure from upper abdomen to thigh
• Look for scars, lumps/swellings bilaterally, scrotal swelling, skin changes (oedema, erythema → strangulation)
• Ask the patient to cough and look for a visible expansile cough impulse
• Ask the patient to look down at toes to tense abdominal muscles (accentuates ventral/incisional hernias)
• Ask the patient to reduce the hernia or reduce by gentle pressure in the direction of the inguinal canal

Step 2 — Palpation (standing) ^[3]:

• Assess size, border, surface, consistency, temperature, tenderness
• Try to get above the hernia — cannot get above = hernia; can get above = think hydrocele/scrotal pathology
• Feel for palpable cough impulse (reduce first, then cough)
• Check for inguinal lymphadenopathy

Step 3 — Supine Examination ^[3]:

• Determine relationship to pubic tubercle and inguinal ligament:
  • Medial + above pubic tubercle → inguinal hernia
  • Below + lateral to pubic tubercle → femoral hernia
• Perform the deep ring occlusion test:
  • Place finger over the deep inguinal ring (2 cm above the midpoint of the inguinal ligament)
  • Ask the patient to stand and cough
  • Direct hernia: hernia reappears medial to the deep ring (not controlled)
  • Indirect hernia: hernia is controlled with pressure on the deep ring
  • Pantaloon hernia: hernia appears slightly on coughing, and appears more fully after removal of compression
• Remove finger and observe the direction of reappearance:
  • Direct hernia: projects forward (straight through Hesselbach's triangle)
  • Indirect hernia: slides obliquely (along the inguinal canal)

Step 4 — Completion ^[3]:

• Genital examination — check for scrotal extension, undescended testis, baseline testicular volume
• Contralateral groin — bilateral hernias are common
• Per rectal (PR) examination — check for BPH (straining as precipitant); lower anal canal drains to superficial inguinal LN
• Per vagina (PV) examination — lower vagina drains to superficial inguinal LN
• Examine abdomen — ascites, organomegaly
• Examine chest — COPD signs (chronic cough as precipitant)

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2. Classification Systems

Classification systems exist to standardise communication and guide surgical approach. Two are highlighted in the lecture slides:

2.1 Nyhus Classification [1]

Designed for the posterior approach based on the size of the internal ring and the integrity of the posterior wall ^[1]:

Why does this matter? The Nyhus system is particularly useful for laparoscopic surgeons operating from the posterior/pre-peritoneal approach (TEP/TAPP), where you are looking at the myopectineal orifice from behind and can assess the internal ring size and posterior wall integrity directly.

2.2 EHS (European Hernia Society) Groin Hernia Classification [1]

A simpler, more practical classification used widely in modern practice:

Example: Primary L2 = a primary indirect inguinal hernia with a defect of 1–2 finger-breadths ^[1].

Why EHS is preferred clinically: It is quick to apply, directly describes the hernia you see, and the size grading correlates with recurrence risk and choice of repair technique. It can be applied both clinically and intraoperatively.

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3. Diagnostic Algorithm

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4. Investigation Modalities

The lecture slides explicitly state the diagnostic hierarchy ^[1]:

Diagnosis: (1) Physical examination alone; (2) Ultrasound; (3) CT; (4) Less commonly still MRI, herniography

Let us work through each modality from first principles, understanding when to use it, what you are looking for, and why.

4.1 No Investigation Required — Clinical Diagnosis

For the vast majority of straightforward, reducible, uncomplicated inguinal or femoral hernias, no investigation is needed ^[1][2]. The physical examination findings are sufficient to make the diagnosis and plan surgery.

• Clinical diagnosis is the standard for inguinal hernia ^[2]
• Investigations are only needed when clinical findings are equivocal or when complications are suspected

4.2 Abdominal X-ray (AXR)

Key findings and interpretation:

4.3 Ultrasound (USG) — First-Line Imaging [1][2][3]

USG groin is the imaging modality of choice ^[3]. It is the most practical, accessible, and cost-effective imaging tool for hernia assessment.

Key USG findings and interpretation:

4.4 CT Scan (CT Abdomen/Pelvis)

CT is indicated when physical examination cannot definitively identify the hernia ^[3], or when complications are suspected and surgical planning requires detailed cross-sectional anatomy.

Key CT findings and interpretation:

4.5 MRI

4.6 Herniography

Less commonly used ^[1] — largely historical but worth knowing:

• Involves injection of water-soluble contrast into the peritoneal cavity, followed by fluoroscopy or X-ray
• The contrast outlines the peritoneal sac if a hernia is present
• Was used for occult hernias when ultrasound and CT were not as advanced
• Largely superseded by dynamic USG and MRI in modern practice
• Risks: contrast allergy, bowel perforation during injection, peritonitis

4.7 Blood Investigations (for Complicated Hernias)

When a hernia presents with features of complications (incarceration, obstruction, strangulation), blood tests are needed not to diagnose the hernia itself but to assess the patient's physiological status and plan for emergency surgery:

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5. Special Diagnostic Scenarios

5.1 Occult Inguinal Hernia

Some patients present with groin pain on exertion but no demonstrable lump on examination. This is the "occult hernia" or early hernia with intermittent protrusion.

• First-line: Dynamic groin USG with Valsalva — may show transient herniation through the deep ring or Hesselbach's triangle
• Second-line: Dynamic MRI with Valsalva — more sensitive for subtle posterior wall bulging
• Consider differential: sportsman's hernia (athletic pubalgia) — there is inguinal canal posterior wall weakness but no true hernial sac; hip pathology (labral tear, FAI); adductor tendinopathy; iliopsoas bursitis

5.2 Incisional Hernia

• Physical examination: define the fascial defect by tilting head up to look at toes (this tenses the rectus, making the fascial defect and hernia bulge more obvious) ^[2]
• Percuss for content — dull = omentum; resonant = bowel ^[2]
• Imaging: CT abdomen/pelvis is the gold standard for incisional hernias — it maps the exact size and location of the defect, identifies contents, and reveals any additional defects (important for surgical planning, especially large/complex incisional hernias)

5.3 Obturator Hernia

• Often no external lump visible (hernia is deep within the pelvis)
• Diagnosed on CT scan showing bowel herniating through the obturator foramen
• Clinical clue: Howship-Romberg sign (pain along the medial thigh on internal rotation of the hip — obturator nerve compression)
• Typically in thin elderly females ("little old lady hernia") ^[2]

5.4 Paediatric Inguinal Hernia [5]

• Clinical diagnosis in children — history of intermittent inguinal/scrotal swelling during crying or straining is often sufficient
• "Silk glove sign" — thickened spermatic cord palpated at the external ring, feeling like rubbing two layers of silk together — suggests a patent processus vaginalis
• USG can be helpful if the hernia is not demonstrable at the time of consultation, but a convincing history from the parents is sufficient for surgical referral in paediatric practice
• Differentiate from communicating hydrocele: hydrocele transilluminates, varies in size over the day, and empties gradually when supine

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6. Summary of Investigation Algorithm by Clinical Scenario

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Active Recall - Diagnosis of Hernia

1. What is the investigation hierarchy for hernia as stated in the lecture slides?

Your answer

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(1) Physical examination alone, (2) Ultrasound, (3) CT, (4) Less commonly MRI or herniography. Most hernias are diagnosed clinically without any imaging.

2. Describe the deep ring occlusion test: how is it performed, what does it differentiate, and what is its accuracy?

Your answer

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Reduce hernia, place finger over deep inguinal ring (2 cm above midpoint of inguinal ligament). Patient stands and coughs. Controlled (hernia does not reappear) = indirect (accuracy 86%). Not controlled (reappears medially) = direct (accuracy only 35%). Definitive classification is made intraoperatively.

3. List the Nyhus classification types 1 through 4 for groin hernias.

Your answer

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Type 1: indirect hernia with normal internal ring. Type 2: indirect hernia with enlarged internal ring. Type 3a: direct inguinal hernia. Type 3b: indirect hernia causing posterior wall weakness (includes pantaloon and sliding). Type 3c: femoral hernia. Type 4: all recurrent hernias.

4. When should an AXR be ordered in the context of hernia? What key findings would you look for?

Your answer

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AXR is NOT routine. Indicated only when intestinal obstruction is suspected (incarcerated/strangulated hernia). Key findings: dilated SB loops (> 3 cm) with air-fluid levels on erect film, absent distal gas, gas shadow within hernia sac in groin. A normal AXR does not exclude obstruction (early stage or Richter's hernia).

5. What are the CT signs that differentiate simple incarceration from strangulation in a hernia?

Your answer

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Strangulation signs: (1) bowel wall thickening with non-enhancement (no contrast uptake = loss of blood supply), (2) mesenteric fat stranding, (3) free fluid in sac or peritoneum, (4) pneumatosis intestinalis (gas in bowel wall = necrosis). These mandate emergency surgery.

6. Explain the EHS groin hernia classification system. How would you classify a primary indirect inguinal hernia with a defect of 1-2 finger-breadths?

Your answer

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EHS uses: Primary/Recurrent, Location (L = Lateral/Indirect, M = Medial/Direct, F = Femoral), Size (1 = 1 finger or less, 2 = 1-2 fingers, 3 = 3 or more fingers, x = not investigated). The described hernia would be classified as Primary L2.

References

^[1] Lecture slides: GC 193. Inguinal and scrotal swelling different types of hernia.pdf (p27, p39, p58, p59) ^[2] Senior notes: maxim.md (Chapter 6 — Hernia: Investigations, Incisional hernia, Femoral hernia) ^[3] Senior notes: felixlai.md (Physical examination, Radiological tests sections) ^[4] Senior notes: maxim.md (Chapter 6.6 — Femoral hernia: Investigations) ^[5] Lecture slides: GC 203. The child needs an operation Common emergencies and surgery in childhood.pdf

Management of Hernia

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1. Overview — Management Principles

The fundamental management decision for any hernia is simple: operate or observe? The answer depends on the hernia type, symptoms, complication risk, and patient fitness.

The core management principles for all hernia repairs are ^[2]:

1. Reduction of hernia contents ± removal of non-viable tissues and repair of bowel
2. Excision and closure of the peritoneal sac
3. Re-approximate the walls of the neck of the hernia
4. Reinforce the abdominal wall defect with sutures or mesh

Before diving into the details, let's define the surgical terminology clearly as stated in the lecture slides ^[1]:

Herniotomy: Excision of the hernia sac after reduction of contents — no reinforcement of the posterior wall. Only used in children (because the abdominal wall tissues in children are healthy and do not need reinforcement — the problem is purely the patent processus vaginalis, not tissue weakness) ^[1][2].

Herniorrhaphy: Herniotomy + strengthening of the posterior wall without mesh — a tissue-based repair using sutures to re-approximate native tissue layers ^[1].

Hernioplasty: Herniotomy + strengthening of the posterior wall with mesh — the modern standard; "tension-free" repair where mesh covers the defect, avoiding muscle fibre distortion that increases tension ^[1][2].

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2. Management Algorithm

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3. Conservative Management

Conservative management (watchful waiting) is an option for asymptomatic inguinal hernia or patients not fit for surgery ^[2][3].

3.1 Indications for Watchful Waiting [1][2]

• Asymptomatic inguinal hernia — the lecture slides state that 70% will become symptomatic and require surgery within 5 years ^[1], but the risk of acute incarceration is low (~1–3% per year for inguinal hernias), so observation is safe in the short term
• Patients unfit for surgery (high anaesthetic risk, concurrent medical problems)
• Pregnancy — pregnant women should not have elective surgical repair of inguinal or femoral hernia until at least 4 weeks after delivery; urgent repair can still be performed if complications arise ^[3]

3.2 Components of Conservative Management [2][3]

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4. Surgical Management — Inguinal Hernia

The lecture slides provide a comprehensive decision tree for inguinal hernia repair ^[1]:

4.1 Decision Framework

The slide outlines the entire treatment pathway ^[1]:

Inguinal hernia → (1) Watchful waiting; (2) Mesh repair; (3) Tissue repair

Within mesh repair:

• Open → Anterior repair (e.g., Lichtenstein) or Posterior repair (e.g., Stoppa)
• Laparoscopic → Posterior repair: TEP, TAPP, eTEP

Within tissue repair:

• Bassini
• Shouldice

4.2 Indications for Surgical Repair [2][3]

4.3 Contraindications to Elective Repair [3]

4.4 Choice Between Open vs Laparoscopic [1][2]

European Hernia Society Guideline (from lecture slides) ^[1]:

• Endoscopic repair recommended for both unilateral and bilateral hernias
• Preferred approach when dealing with recurrent hernia after open repair

4.5 The "Opposite Approach" Principle for Recurrence [1]

When a hernia recurs, choose the opposite approach to avoid scar tissue ^[1]:

Rationale: operating through virgin tissue planes (not through previous scar tissue) reduces the risk of injury, is technically easier, and has better outcomes ^[1].

4.6 Females — Special Considerations [1]

• Laparo-endoscopic repair recommended for women
• Why? (1) Decrease chronic pain risk (laparoscopic approach avoids the superficial inguinal nerves), (2) Avoid missing a femoral hernia (laparoscopic posterior view allows visualisation of the entire myopectineal orifice, including the femoral ring — a femoral hernia that was clinically misdiagnosed as inguinal can be identified and repaired simultaneously)
• Pregnant women → Watchful waiting → self-limiting round ligament varicosities (an important differential that resolves postpartum and does not require surgery) ^[1]

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5. Specific Open Repair Techniques — Inguinal Hernia

5.1 Mesh Repairs (Hernioplasty)

A. Lichtenstein Repair (Anterior open mesh repair) ^[1][2][3]

This is the gold standard open repair for inguinal hernia worldwide.

B. Stoppa Repair (Posterior open mesh repair) ^[1]

5.2 Non-Mesh Repairs (Herniorrhaphy)

Non-mesh tissue repairs have a higher recurrence rate but are indicated in patients with active groin infection or contamination as a result of bowel perforation from strangulated hernia ^[3] (you cannot place a prosthetic mesh in a contaminated field — it would become an infected foreign body).

A. Shouldice Repair ^[1][3]

B. Bassini Repair ^[1][3]

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6. Laparoscopic Repair Techniques — Inguinal Hernia

All laparoscopic approaches use mesh placed in the pre-peritoneal (sublay) position, which is the strongest position biomechanically — intra-abdominal pressure pushes the mesh against the abdominal wall, reinforcing it (Pascal's principle).

6.1 TEP — Totally Extraperitoneal Repair [1][2][3]

6.2 TAPP — Transabdominal Pre-peritoneal Repair [1][2][3]

6.3 eTEP — Extended Totally Extraperitoneal Repair [1]

A newer evolution of TEP that uses a crossover technique to access both groins entirely extraperitoneally through a single set of ports. Increasingly popular for bilateral and complex hernias.

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7. Mesh — Types and Positioning [2]

7.1 Mesh Types

7.2 Mesh Positioning [2]

Key point: Open repair allows all mesh positions; laparoscopic repair only allows sublay ^[2].

7.3 When Mesh Cannot Be Used

Mesh may be difficult if complicated hernia (infected / oedematous) → use non-mesh repair ^[2]:

• Active infection (mesh acts as a foreign body nidus)
• Grossly contaminated field (bowel perforation with faecal peritonitis)
• Severely oedematous tissues (mesh cannot be fixed properly; tissue ingrowth is impaired)

In these circumstances, use a tissue repair (Shouldice or Bassini) or consider biological mesh if mesh reinforcement is strongly desired.

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8. Surgical Management — Femoral Hernia [1][3][4]

All femoral hernias should be treated surgically — there is no role for watchful waiting ^[2][4].

The lecture slides state: Femoral hernia repair — (a) Lockwood's infrainguinal approach; (b) Lotheissen's transinguinal approach; (c) McEvedy's high approach — depends whether there is strangulation ^[1].

8.1 Open Approaches

8.2 Laparoscopic Repair

TEP or TAPP — usually reserved for elective cases ^[4]. The posterior laparoscopic view allows excellent visualisation of the femoral ring, and a large mesh can be placed to cover both the inguinal and femoral defects simultaneously.

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9. Surgical Management — Other Hernia Types

9.1 Incisional Hernia [2][4]

Conservative:

• Lifestyle modification, treat medical conditions, truss
• Indicated if: high anaesthetic risk, concurrent medical problems, risk of infection/dehiscence/haematoma

Surgical repair (open or laparoscopic) — indicated if symptomatic or risk of strangulation ^[2]:

• Dissect hernia sac and surrounding tissues ≥ 3 cm on all sides
• Reduce hernia contents and repair the fascial defect
• Defects < 1 cm: Mayo repair — fascial edge repaired with 2 cm overlap, using interrupted + continuous sutures
• Defects > 1 cm: tension-free mesh repair — allow 5–8 cm adequate overlapping over normal tissues for mesh shrinkage/contraction in ALL directions
• Sublay has the lowest recurrence rate ^[2]

9.2 Umbilical / Paraumbilical Hernia [2][3][4]

• Congenital (children): repair if symptomatic; most close spontaneously by age 3–5 ^[2][4]
  • Surgery indicated if: persists beyond age 4–5, defect > 1.5–2 cm, symptomatic, incarceration
• Acquired (adults): always consider surgery ^[4]
  • Small defect: Mayo repair
  • Large defect: sublay extra-peritoneal mesh ^[4]
• Small and asymptomatic hernia do NOT require repair and can be observed ^[3]

9.3 Hiatus Hernia [2]

• Conservative: indicated if sliding hernia (Type 1) — weight loss, smoking cessation, reduce alcohol, treat GERD with PPI
• Surgical (hernia repair + Nissen fundoplication): indicated in:
  • Symptomatic despite maximum medical treatment
  • Rolling type (Type 2–4): increased risk of gastric volvulus — surgical emergency ^[2]

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10. Paediatric Hernia Management [5]

Inguinal hernia and hydrocele share the same aetiology — patent processus vaginalis (PPV) ^[5]:

Key paediatric points ^[5]:

• Hernias are common in neonates (30% in premature babies)
• Increased bilateral hernias with decreasing age
• Bowel strangulation is a potential complication — incarceration rate highest in infants < 6 months
• In children: herniotomy only (no mesh, no hernioplasty) — simply excise the patent processus vaginalis (c.f. mesh repair in adults) ^[2]
• Open or laparoscopic herniotomy — laparoscopic approach allows visualisation of the contralateral internal ring (useful given the high bilateral rate in young infants)

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11. Emergency Management — Complicated Hernia [2][3]

When a hernia presents as an emergency (incarcerated, obstructed, or strangulated), the approach follows a systematic resuscitation → assessment → surgery pathway:

11.1 Resuscitation (Drip and Suck) [3]

11.2 Attempt at Manual Reduction

• Taxis (gentle manual reduction) may be attempted for incarcerated but NOT strangulated hernias
• Apply gentle, sustained pressure with the patient in Trendelenburg position (head down) ± analgesia/sedation to relax the abdominal wall
• Manual reduction should NOT be performed if there are signs of strangulation (peritonitis, systemic sepsis, skin changes) ^[2] because:
  • Risk of reduction-en-masse (apparently "reduced" but sac and contents pushed together behind fascia → still strangulated)
  • Risk of peritonitis if ischaemic/gangrenous bowel is reduced into the peritoneal cavity
  • Recurrence is likely ^[2]

11.3 Surgical Exploration

• If reduction fails or strangulation is suspected → emergency inguinal exploration (for inguinal hernia) or McEvedy's approach (for femoral hernia — better access to bowel)
• Intraoperative assessment of bowel viability — the 6 P's: cold, pulsation, pallor, peristalsis (and colour, perforation) ^[2]

• If viable: reduce contents → repair hernia (mesh if tissues appear normal or only mildly oedematous; non-mesh if contaminated) ^[3]
• If non-viable: resect non-viable bowel → primary anastomosis (if clean field, stable patient) or stoma (if contaminated, unstable) → non-mesh hernia repair (contaminated field)

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12. Post-Operative Management [2][3]

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13. Summary Table — Management by Hernia Type

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Active Recall - Management of Hernia

1. Define herniotomy, herniorrhaphy, and hernioplasty. In which patient population is herniotomy alone appropriate?

Your answer

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Herniotomy = excision of hernia sac after reduction of contents, no wall reinforcement. Herniorrhaphy = herniotomy + strengthening of posterior wall WITHOUT mesh. Hernioplasty = herniotomy + strengthening with mesh. Herniotomy alone is used in children because their abdominal wall tissues are healthy — the problem is the patent processus vaginalis, not tissue weakness.

2. Why is Lichtenstein repair not applicable to femoral hernia? What approach should be used instead?

Your answer

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Lichtenstein places mesh anterior to the posterior wall of the inguinal canal, above the inguinal ligament. The femoral ring is below the inguinal ligament in a different compartment, so the mesh cannot reach it. For femoral hernia use: Lockwood's infrainguinal (elective), Lotheissen's transinguinal, or McEvedy's suprainguinal (emergency). Laparoscopic TEP/TAPP also covers the femoral ring from posteriorly.

3. A hernia recurs after a previous open anterior (Lichtenstein) repair. What surgical approach should be used for the recurrence, and why?

Your answer

Grade

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Use a posterior approach (laparoscopic TEP or TAPP). The principle is to avoid scar tissue from the previous repair by choosing the opposite approach — operating through virgin tissue planes reduces injury risk, is technically easier, and has better outcomes.

4. List the indications for emergency surgery in a patient with a complicated hernia presenting with intestinal obstruction.

Your answer

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Strangulated (complicated) obstruction; closed-loop obstruction; peritonitis; incarcerated or strangulated hernia with failed manual reduction or signs of bowel compromise. Also: failed conservative management after 72 hours.

5. When can mesh be used in an emergency hernia repair, and when should it be avoided?

Your answer

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Mesh is safe if tissues appear normal or only mildly oedematous and there is no contamination. Mesh should be avoided (use tissue repair or biological mesh) if there is: active infection, gross contamination from bowel perforation, severely oedematous tissues, or faecal peritonitis.

6. Describe the management approach for incisional hernia including indications for conservative vs surgical treatment and the choice of repair technique based on defect size.

Your answer

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Conservative (truss, lifestyle modification, treat medical conditions): indicated if high anaesthetic risk, asymptomatic, concurrent medical problems. Surgical: indicated if symptomatic or risk of strangulation. Defect < 1 cm: Mayo repair (fascial overlap 2 cm, interrupted + continuous sutures). Defect > 1 cm: tension-free mesh repair with 5-8 cm overlap in all directions. Sublay position has the lowest recurrence rate.

References

^[1] Lecture slides: GC 193. Inguinal and scrotal swelling different types of hernia.pdf (p41, p42, p43, p53, p57, p64, p65, p66) ^[2] Senior notes: maxim.md (Chapter 6 — Hernia: Surgery, Mesh, Incisional hernia, Umbilical hernia, Femoral hernia, Post-op recovery, Complications) ^[3] Senior notes: felixlai.md (Treatment — Inguinal hernia, Femoral hernia, Complications, Post-op follow-up) ^[4] Senior notes: maxim.md (Chapter 6.6 — Femoral hernia management; Chapter 6.5 — Umbilical hernia) ^[5] Lecture slides: GC 203. The child needs an operation Common emergencies and surgery in childhood.pdf (p6, p9)

Complications of Hernia

Complications of hernia fall into two broad categories: (A) complications of the hernia itself (the disease process) and (B) complications of hernia repair (the surgical treatment). Both are high-yield and must be understood from first principles.

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Part A — Complications of the Hernia (Disease Complications)

These are the complications that arise from an untreated or under-treated hernia progressing along the pathophysiological sequence we established in earlier sections: reducible → irreducible → incarcerated → obstructed → strangulated → infarcted.

A1. Irreducibility

• Definition: bowel becomes trapped and unable to return to the main peritoneal cavity because adhesions have formed between contents and sac wall, or the defect is too small relative to the contents that have entered ^[3]
• Why it happens: repeated episodes of herniation cause chronic friction between the sac lining and its contents (omentum or bowel serosa) → fibrinous adhesions develop → contents become fixed within the sac
• Significance: an irreducible hernia is at constant risk of progressing to incarceration and strangulation — it cannot decompress itself

A2. Intestinal Obstruction [3]

A loop of bowel is trapped in the hernia sac such that the bowel lumen (but not its blood supply) is obstructed ^[3].

This is a closed-loop obstruction when both the afferent and efferent limbs of the bowel loop are trapped at the hernia neck. Closed-loop obstruction is particularly dangerous because:

1. The trapped loop cannot decompress in either direction
2. Intraluminal pressure rises rapidly → compromises venous return in the bowel wall
3. Rapid progression to strangulation

Hernia is the 2nd most common cause of small bowel obstruction (after adhesions) — accounting for approximately 10% of all SBO cases ^[2].

A3. Strangulation — The Most Serious Complication [3]

Bowel necrosis as a result of strangulation is the most serious complication ^[3].

The pathophysiological cascade — understanding this from first principles:

Strangulation risk by hernia type ^[2]:

Incidence of strangulation: femoral > indirect inguinal > direct inguinal ^[2]

Why? The risk is inversely proportional to the neck diameter:

• Femoral ring — smallest and most rigid (bounded by ligaments and the femoral vein) → highest strangulation risk
• Deep inguinal ring (indirect) — relatively narrow muscular ring → moderate risk
• Hesselbach's triangle (direct) — broad-based defect → rarely strangulates

Clinical features suggestive of strangulation ^[3]:

Prognosis: morbidity and mortality are dependent on the duration of ischaemia and its extent. Any length of ischaemic bowel can cause significant systemic effects secondary to sepsis and dehydration ^[3].

A4. Incarceration — Specific Organ Damage [3]

Incarceration of inguinal hernia causes organ-specific complications depending on the patient's sex ^[3]:

• Males: compromise of blood supply to the testes resulting in ischaemic necrosis and atrophy, as well as injury to the vas deferens — the spermatic cord structures are compressed at the hernia neck alongside the bowel
• Females: torsion rather than direct compression compromises blood supply to the ovaries — in girls and women, the ovary (± fallopian tube) may herniate and undergo torsion within the sac

Paediatric: bowel strangulation is a potential complication of inguinal hernia in neonates and infants ^[5]. The incarceration rate is highest in the first 6 months of life (~30%) because:

• The hernia neck (deep ring) in infants is relatively small compared to the bowel volume that can enter
• Infants cannot communicate symptoms effectively → delayed presentation

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Part B — Complications of Hernia Repair (Post-Operative Complications)

These are classified by timing into immediate, early, and late ^[2][3].

B1. Immediate Complications (Intra-operative / first 24 hours)

B2. Early Complications (Days to weeks post-operatively)

B3. Late Complications (Weeks to months to years post-operatively)

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Chronic Postoperative Inguinal Pain (CPIP) — Deep Dive

This deserves special attention because the lecture slides dedicate a separate section to it ^[1]:

CPIP ^[1]:

• Affects 10–12% of inguinal hernia repair patients
• Defined as bothersome moderate pain impacting daily activities lasting at least 3 months postoperatively
• Risk factors: young age, female gender, high preoperative pain, early high postoperative pain, recurrent hernia, and open repair

Pathophysiology: Three mechanisms of nerve injury cause CPIP:

The three key nerves at risk ^[2]:

1. Ilioinguinal nerve — runs on the spermatic cord surface within the inguinal canal; sensory to the inguinal region, upper medial thigh, and root of penis/scrotum (or mons pubis/labium majus)
2. Iliohypogastric nerve — runs between internal oblique and transversus abdominis; sensory to the suprapubic region
3. Genital branch of the genitofemoral nerve — runs through the deep ring alongside the spermatic cord; motor to cremaster, sensory to the anterolateral scrotum/labium
4. Lateral femoral cutaneous nerve of the thigh — can be injured during laparoscopic dissection in the pre-peritoneal space (runs lateral to the external iliac artery on the iliopsoas) → meralgia paraesthetica (numbness/burning over the anterolateral thigh)

Management of CPIP:

• Prevention (most important): minimised by avoiding manipulation of nerves during dissection and repair, or by selective neurectomy ^[3]
  • If a nerve is directly in the surgical field and cannot be safely preserved → prophylactic neurectomy is better than leaving a damaged nerve in situ
  • Laparoscopic repair has less chronic pain because it is performed at a deeper level away from the 3 nerves ^[2]
• Treatment of established CPIP:
  • Conservative: neuropathic pain medications (gabapentin, pregabalin, amitriptyline), local nerve blocks, physiotherapy
  • Interventional: ultrasound-guided nerve blocks (diagnostic and therapeutic)
  • Neurectomy is selected for cases involving inadvertent trauma to a nerve or when the location of the nerve would make entrapment with sutures during mesh fixation ^[3] — can be performed as a primary procedure if nerve injury is recognised intraoperatively, or as a secondary procedure for refractory CPIP
  • Mesh removal: if the pain is thought to be mesh-related (meshoma, mesh erosion, chronic inflammatory response)

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Complications of Incisional Hernia [2]

Incisional hernias carry their own specific set of complications:

• Intermittent obstruction — bowel enters and exits the sac, causing episodic obstructive symptoms
• Incarceration / strangulation — same pathophysiology as groin hernias
• Enterocutaneous fistula — if bowel adheres to the sac wall and erodes through the skin → faecal discharge through the skin → skin excoriation ^[2]
• Loss of domain — in very large incisional hernias, so much abdominal content has herniated into the sac that the abdominal cavity has "shrunk" and can no longer accommodate the contents if they were reduced. This creates a massive surgical challenge (reducing the hernia contents raises intra-abdominal pressure → abdominal compartment syndrome)

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Complications of Hiatus Hernia [6]

For completeness:

• Gastric volvulus (only in rolling type / Type 2–4) — the herniated stomach rotates → obstruction → ischaemia. Borchardt's triad: retching without vomiting, epigastric distension, inability to pass NG tube. This is a surgical emergency ^[6].
• Strangulation of the herniated stomach
• Gastric perforation → mediastinitis
• Gangrene of the herniated stomach wall
• Management of complications: NG tube decompression + emergency operation (EOT) ^[6]

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Summary — Master Table of Complications

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Active Recall - Complications of Hernia

1. Describe the pathophysiological sequence from incarceration to gangrene in a strangulated hernia. Why are veins affected before arteries?

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Narrow hernia neck compresses thin-walled veins first (lower intraluminal pressure than arteries) causing venous congestion. Congestion causes bowel wall oedema, which further increases tissue pressure. Rising pressure eventually occludes thicker-walled arterioles causing arterial ischaemia. Mucosal barrier fails allowing bacterial translocation. Full-thickness necrosis (gangrene) ensues, leading to perforation, faecal peritonitis, sepsis and death if untreated.

2. What is CPIP? State its incidence, definition, and risk factors as per the lecture slides.

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Chronic Postoperative Inguinal Pain. Incidence: 10-12% of inguinal hernia repair patients. Definition: bothersome moderate pain impacting daily activities lasting at least 3 months postoperatively. Risk factors: young age, female gender, high preoperative pain, early high postoperative pain, recurrent hernia, and open repair.

3. Name the three nerves most at risk during inguinal hernia repair and explain why laparoscopic repair causes less chronic pain.

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Ilioinguinal nerve, iliohypogastric nerve, and genital branch of the genitofemoral nerve. Laparoscopic repair is performed from the posterior/pre-peritoneal approach at a deeper level away from these three nerves (which lie in the anterior inguinal canal), hence less risk of nerve injury and less chronic pain.

4. A patient develops a painless fluctuant swelling at the hernia repair site 2 weeks post-operatively with no fever or skin changes. What is the most likely diagnosis and how should it be managed?

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Seroma — collection of serous fluid in the dead space remaining after hernia sac reduction, due to inflammatory response to mesh/sutures. Management: reassurance and observation. Do NOT aspirate unless there are signs of secondary infection (fever, erythema, warmth), as aspiration risks introducing bacteria into a sterile space containing prosthetic mesh.

5. Why is Richter's hernia a particularly dangerous complication, and with which hernia type is it classically associated?

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Richter's hernia involves only one sidewall of the bowel, so it causes ischaemia and potential necrosis/perforation WITHOUT causing complete intestinal obstruction. The absence of classic obstruction symptoms (vomiting, distension, constipation) delays diagnosis. It is classically associated with femoral hernias because the small, tight femoral ring catches just a knuckle of bowel wall.

6. List the clinical, biochemical, and radiological features that suggest bowel strangulation in a patient with an incarcerated hernia.

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Clinical signs: fever, tachycardia, peritoneal signs (guarding, rigidity, rebound). Clinical symptoms: continuous or worsening abdominal pain (transition from colicky to constant). Biochemical: leucocytosis, metabolic acidosis (raised lactate). Radiological: pneumoperitoneum (perforation), pneumatosis intestinalis (gas in bowel wall from necrosis), portal venous gas (extensive bowel necrosis).

References

^[1] Lecture slides: GC 193. Inguinal and scrotal swelling different types of hernia.pdf (p19, p61) ^[2] Senior notes: maxim.md (Chapter 6 — Hernia: Specific complications, Incisional hernia complications, Definitions) ^[3] Senior notes: felixlai.md (Complications of hernia, Post-operative complications, Descriptive terminology) ^[5] Lecture slides: GC 203. The child needs an operation Common emergencies and surgery in childhood.pdf (p6) ^[6] Senior notes: maxim.md (Hiatus hernia — Complications)