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HERNIA — Exam-Oriented Review

Definition

• Roberts & Hedges' Clinical Procedures in Emergency Medicine

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Parts of a Hernia (Must Know)

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Classification

A. By Reducibility (Most Important for Exams)

⚠️ Key exam point: Obstructed hernia ≠ Strangulated. In strangulation there is both obstruction + vascular compromise. Femoral hernias are most prone to strangulation (incarcerate in up to 45% of cases due to tight neck).

B. By Etiology

• Congenital — patent processus vaginalis (indirect inguinal, umbilical in children)
• Acquired — weakness from aging, raised intra-abdominal pressure, poor wound healing

C. Richter's Hernia

D. Littre's Hernia

E. Sliding Hernia (en-glissade)

F. Maydl's Hernia (Hernia-in-W)

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Types of Hernia by Location

1. Indirect Inguinal Hernia ⭐ (Most Common Overall)

• Passes through the deep (internal) inguinal ring → inguinal canal → may reach scrotum
• Located lateral to inferior epigastric vessels
• Occurs because of patent processus vaginalis
• Most common in males, children, and young adults
• ~5% of full-term infants, ~30% of preterm infants
• Congenital in children; can be acquired in adults

2. Direct Inguinal Hernia

• Protrudes through Hesselbach's triangle (bounded by inferior epigastric vessels laterally, rectus abdominis medially, inguinal ligament inferiorly)
• Located medial to inferior epigastric vessels
• Acquired; more common after age 40
• Appears on standing, disappears immediately on lying down
• Rarely strangulates (wide neck)

3. Femoral Hernia

• Protrudes through the femoral canal (below inguinal ligament)
• Boundaries of femoral canal: femoral vein (lateral), inguinal ligament (anterior), iliopectineal/Astley Cooper's ligament (posterior), lacunar/Gimbernat's ligament (medial)
• More common in women (but inguinal hernia is still more common than femoral even in women overall)
• Appears as a medial thigh mass below the inguinal ligament
• High strangulation risk (45% incarceration) — tight neck is the reason
• No cough impulse when irreducible → commonly misdiagnosed as lymph node

4. Pantaloon Hernia

• Combination of direct + indirect hernia straddling the inferior epigastric vessels
• Difficult to diagnose and reduce manually; usually found at surgical exploration

5. Umbilical Hernia

• Traverses the fibromuscular umbilical ring
• In children: congenital, usually resolves by age 5; repair if >2 cm, persists >5 years, or incarcerates
• In adults: acquired; associated with obesity, ascites, pregnancy; higher risk of strangulation than in children
• Treatment: Mayo repair (fascial overlap "waistcoat over trousers") or mesh for defects >2 cm

6. Epigastric Hernia

• Through linea alba between umbilicus and xiphoid
• Usually contains extraperitoneal fat (rarely bowel)
• Often small and symptomatic; repair recommended

7. Incisional Hernia (Ventral)

• Occurs in up to 20% of patients after abdominal surgery
• Risk factors: wound infection, obesity, malnutrition, steroids
• Recurrence rate: 20–50% after repair
• Larger defects paradoxically have lower risk of strangulation (wider neck)

8. Spigelian Hernia

• Through the spigelian fascia (lateral edge of rectus abdominis at the semilunar line)
• Rare; lies between muscle layers → interparietal (difficult to detect clinically)
• Located just lateral to the rectus, usually below umbilicus

9. Hiatal Hernia

• Protrusion of stomach through the oesophageal hiatus of the diaphragm

Types II/III/IV can cause volvulus and strangulation → surgical emergency.

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Complications

1. Irreducibility → Incarceration
2. Obstruction → Bowel obstruction (no vascular compromise)
3. Strangulation → Vascular compromise → gangrene → perforation → peritonitis
4. Inflammation / Maydl's (internal strangulation without external signs)
5. Rupture (rare; umbilical in cirrhosis with ascites)

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Clinical Features

• Reducible: Intermittent swelling; increases on standing/coughing; reduces on lying flat
• Cough impulse: Expansile impulse on coughing (hallmark); absent in tight-necked hernias
• Strangulated: Tense, tender, non-reducible; no cough impulse; overlying skin erythema; signs of bowel obstruction; systemic toxicity
• Examination: supine → standing → Valsalva/cough; examine contralateral side (occult hernia in 20%)

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Investigations

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Treatment

Conservative

• Truss/binder: reserved for patients unfit for surgery (temporary measure, not curative)
• Watch-and-wait: asymptomatic male inguinal hernia (watchful waiting is safe; risk of strangulation ~0.3%/year)

Surgical — Principles

Inguinal Hernia Repair

Lichtenstein described tension-free flat polypropylene mesh repair in the 1980s — it remains the most widely performed technique. Laparoscopic repair (TEP/TAPP) is preferred for bilateral or recurrent inguinal hernias after prior open repair.

Femoral Hernia Repair

Umbilical Hernia Repair

• Mayo repair: "Waistcoat-over-trousers" fascial overlap (defects ≤2 cm)
• Mesh repair: preferred for defects >2 cm (lower recurrence)

Incisional Hernia Repair

• Mesh repair mandatory (suture repair has very high recurrence)
• Laparoscopic or open; retromuscular (sublay) mesh placement preferred

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Key Exam One-Liners

• Most common hernia overall: Indirect inguinal
• Most common hernia in females: Indirect inguinal (but femoral is proportionally more common in women vs. men)
• Most likely to strangulate: Femoral hernia
• Hernia that resolves spontaneously: Umbilical (in children <5 years)
• Emergency indication for hernia surgery: Strangulation
• Obstructed ≠ Strangulated: Obstructed has lumen blockage only; strangulated has blood supply compromise
• Richter's hernia: No bowel obstruction; silent strangulation of bowel wall
• Littre's hernia: Contains Meckel's diverticulum
• Maydl's hernia: W-shaped; intra-abdominal loop strangulates first
• Sliding hernia: Viscus forms part of sac wall (sigmoid/caecum/bladder)
• Lichtenstein repair: Tension-free, open mesh; gold standard
• TEP/TAPP: Preferred laparoscopic approaches; indicated for bilateral/recurrent hernias
• Mayo repair: Umbilical hernia; overlapping fascial repair

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