External Abdominal Hernias

1. Classification of Hernias

By Location (Type)

By Reducibility / Clinical Status

• Reducible: Contents return spontaneously or with gentle pressure
• Irreducible (Incarcerated): Contents cannot be reduced; not yet ischemic
• Strangulated: Blood supply compromised → ischemia/necrosis; surgical emergency
• Richter hernia: Only a portion of the bowel wall (antimesenteric) is incarcerated — strangulation can occur without complete bowel obstruction

By Aetiology

• Congenital (e.g., failure of processus vaginalis to close → indirect inguinal)
• Acquired (e.g., direct inguinal from fascial weakening with age; incisional after poor wound healing)

2. General Symptoms

• Visible/palpable bulge at the hernia site — often the primary complaint
• Aching or dragging discomfort, worsened by prolonged standing, straining, coughing, or exertion
• Impulse on coughing — bulge increases with Valsalva
• Reducibility — bulge disappears on lying down in uncomplicated hernias
• Bowel obstruction symptoms (if incarcerated) — colicky abdominal pain, nausea, vomiting, distension, absolute constipation
• Acute severe pain (if strangulated) — constant, unrelenting pain at the hernia site, systemic signs of sepsis

A crucial clinical point: femoral and obturator hernias may cause bowel obstruction without an obvious groin mass — careful groin examination is mandatory in any patient presenting with obstruction. — Mulholland and Greenfield's Surgery, p. 2429

3. Diagnosis

History and Physical Examination

• Elicit onset, duration, reducibility, and any episodes of acute pain or obstruction
• Examine the patient standing and supine; ask patient to cough or strain
• Assess reducibility, tenderness, and bowel sounds over the hernia
• Auscultation over the sac — bowel sounds confirm intestinal content

Imaging

• CT scan is the gold standard for complex, internal, or uncertain hernias (e.g., CT pelvis/abdomen with axial and coronal views to identify herniating segment and hernia orifice — see Figure 49.6 in Mulholland)
• Ultrasound is useful for Spigelian hernias and equivocal groin swellings; also used to guide reduction
• Plain radiograph: may show air-filled bowel loops in hernia sac in obstruction

Indirect inguinal hernia — Roberts and Hedges' Clinical Procedures in Emergency Medicine

Direct inguinal hernia — Roberts and Hedges' Clinical Procedures in Emergency Medicine

4. Types of Hernia Repair

Tension-Based (Tissue) Repairs

• Shouldice repair: Multi-layer imbrication of the posterior inguinal wall; recurrence < 1% at the Shouldice Clinic (though not reproducible universally)
• Bassini repair: Classic primary tissue repair, now largely superseded
• Preferred in contaminated fields (strangulated hernia with bowel resection) to avoid mesh infection

Tension-Free Repairs (Preferred for Elective Cases)

• Lichtenstein (open anterior mesh): Polypropylene mesh placed over posterior inguinal wall; recurrence ≤ 2% at specialist centres; the standard tension-free repair
• Plug and patch: Mesh plug placed in internal ring + flat mesh overlay
• Preperitoneal mesh: Mesh placed posterior to transversalis fascia

Laparoscopic Repairs

• TAPP (Transabdominal PrePeritoneal): Mesh placed via laparoscope through the peritoneal cavity into the preperitoneal space
• TEP (Totally Extraperitoneal): Mesh placed entirely in the preperitoneal space without entering the peritoneal cavity — avoids intraperitoneal organ injury
• eTEP (Enhanced-View TEP): Extended dissection plane allowing larger mesh placement
• Robotic-assisted: Increasing adoption for both TAPP and TEP; equivalent outcomes to laparoscopic in experienced hands
• Laparoscopic approaches are associated with lower short- and long-term risks for intestinal obstruction and faster recovery

Ventral/Incisional Hernia Repair

• Onlay mesh: Mesh placed superficial to the anterior fascial repair
• Sublay (retromuscular/component separation): Mesh placed posterior to rectus muscles in the retromuscular plane — lower recurrence and infection rates
• Intraperitoneal onlay mesh (IPOM): Mesh placed intraperitoneally with anti-adhesion coating; laparoscopic or robotic

Mesh significantly reduces recurrence vs. primary tissue repair. Contamination (bowel resection, enterotomy) increases wound infection, fistula, reoperation, and mortality risk with synthetic mesh — clinical judgment and surgeon experience guide mesh vs. tissue repair in emergency settings. — Mulholland and Greenfield's Surgery, pp. 2431–2432

5. Patient Preparation for Surgery and Postoperative Management

Preoperative Preparation

• Optimise comorbidities: Correct electrolyte and metabolic disturbances; optimise glycaemic control; treat pulmonary disease (smoking cessation reduces risk of pulmonary and wound complications)
• Nutritional optimisation: Address hypoalbuminaemia; carbohydrate loading as part of ERAS protocols reduces postoperative ileus
• Weight reduction for morbidly obese patients reduces hernia recurrence and wound complications
• Bowel preparation: Not routinely required for elective inguinal hernia; may be indicated for ventral/incisional hernia repair where bowel injury risk is significant
• Antibiotics: Single dose prophylaxis for mesh repair
• Fluid resuscitation: Essential in emergency/strangulated cases — IV fluids, correct fluid/electrolyte deficits; nasogastric decompression if obstructed

Anesthetic Considerations

• Elective inguinal hernia repair is commonly performed under local anaesthesia + sedation, regional (spinal), or general anaesthesia
• Local anaesthesia preferred in high-risk patients to minimize urinary retention risk
• Spinal anaesthesia is associated with comparable outcomes; general anaesthesia used for laparoscopic cases

Postoperative Management (ERAS)

• Early mobilisation: Encouraged from day of surgery; reduces ileus and pulmonary complications
• Early oral feeding: Stimulates propulsive bowel motility and immune function; reduces anastomotic dehiscence risk
• Pain management: Multimodal analgesia (NSAIDs + paracetamol ± local nerve block); minimise opioids to reduce ileus and urinary retention
• Fluid management: Avoid perioperative fluid overload; standardise perioperative fluid protocols
• Urinary catheter: Not routinely required; remove early to facilitate mobilisation
• Wound care: Monitor for seroma, haematoma, or infection
• Activity restriction: Avoid heavy lifting for 4–6 weeks post open repair; return to normal activities sooner after laparoscopic repair

6. Complications of Hernias

Complications Related to the Hernia Itself

Complications of Hernia Repair

• Tissue repairs: ~10%+
• Tension-free mesh repairs: ≤ 2% at specialist centres
• Factors increasing recurrence: contaminated field, emergency repair, sutured repair without mesh, early postoperative complications, reoperation for recurrence
• Incisional hernias: 20–50% recurrence with primary suture repair

7. Strangulated Hernia

Definition

Incarceration Risks by Hernia Type

Clinical Features

• Severe, constant pain at the hernia site — no longer relieved by reducing the hernia
• Tender, tense, irreducible swelling — erythema and oedema of overlying skin in late cases
• Systemic signs: fever, tachycardia, leucocytosis → signs of sepsis with perforation
• Bowel obstruction symptoms if lumen is compromised (absent in Richter hernia until > 50% circumference involved)
• Absence of cough impulse — contents are strangulated and fixed

Management — Surgical Emergency

1. Resuscitation: IV fluids, correct electrolytes and acid-base; IV broad-spectrum antibiotics (covering gram-negatives and anaerobes); nasogastric decompression if obstructed
2. Urgent surgery: Do not delay — the hernia is reduced, contents assessed for viability
   • Viable bowel: Reduce and leave; repair the hernia defect
   • Non-viable bowel: Resect + primary anastomosis or stoma depending on contamination and patient stability
3. Mesh use in strangulation: Controversial. For inguinal hernias, current evidence does not treat mesh as contraindicated, but open tissue repair is generally preferred to save mesh for recurrence should it occur. For ventral hernias without ischemia, mesh can be used; with bowel resection and contamination, mesh risks (infection, fistula) increase significantly
4. Postoperative care: ICU if septic; wound surveillance; may require staged repair

Femoral hernias are particularly prone to incarceration and bowel necrosis due to the small size of the hernia inlet. When hernia is identified as the cause of obstruction, the patient is quickly resuscitated, given antibiotics, and taken to the operating room. — Mulholland and Greenfield's Surgery, p. 2429