Hernia - A Comprehensive Surgical Overview

1. Definition

2. Anatomy and Causes of Herniation

• Anatomical weakness
• Developmental failures (e.g., patent processus vaginalis)
• Genetic weakness of collagen
• Sharp and blunt trauma
• Ageing and pregnancy
• Primary neurological and muscle diseases

3. Pathophysiology

• A surgical scar has only 70% of original muscle strength even with perfect healing - hence incisional hernia in >10% of laparotomy wounds
• Laparoscopic port-site hernia rate is approximately 1%

4. Components of a Hernia

1. The defect - opening in the fascial/muscular wall (small rigid defects carry highest strangulation risk)
2. The content - tissue/organ protruding through (fat, omentum, bowel, bladder)
3. The sac - a covering of peritoneum dragged through the defect (not always present)

Types by reducibility:

Special types:

• Richter's hernia - Only part of the bowel wall (antimesenteric) is caught in the defect; complete obstruction may be absent but strangulation can still occur silently
• Littre's hernia - Sac contains a Meckel's diverticulum
• Maydl's hernia - Two loops of bowel in the sac; the intervening loop inside the abdomen becomes strangulated ("W" hernia)

5. Classification of Hernia

A. By location:

• Inguinal (indirect / direct)
• Femoral

6. INGUINAL HERNIA

Anatomy of the Inguinal Canal

• Deep inguinal ring: defect in transversalis fascia, located midway between ASIS and pubic tubercle (~2-3 cm above and lateral to femoral artery pulse)
• Inferior epigastric vessels lie just medial to the deep ring - this is the key anatomical landmark
• Conjoint tendon: fused transversus abdominis + internal oblique, arches over the ring
• Superficial inguinal ring: inverted V-shaped defect in external oblique aponeurosis

Direct vs. Indirect Inguinal Hernia

Diagnosis of Inguinal Hernia

• Usually clinical
• Digital examination: finger in inguinal canal - cough impulse at fingertip = indirect; impulse on dorsum of finger = direct
• Imaging (US, CT, MRI) reserved for ambiguous/occult cases
• Differential: lymph node, hydrocele, varicocele, femoral vessel aneurysm, lipoma, psoas abscess, testicular tumor

Surgical Repair Options

Open Suture Repairs (no mesh)

• Bassini's repair (1890): Sutures between conjoint tendon (above) and inguinal ligament (below), from pubic tubercle to deep ring. Standard for >100 years.
• Shouldice repair: Transversalis fascia opened, then double-breasted closure creates two-layer posterior wall. <2% lifetime failure in expert centres; technically demanding.
• Maloney repair (modified Bassini): Continuous non-absorbable (nylon/polypropylene) darn. Most common in resource-limited settings.
• Desarda repair: Strip of external oblique aponeurosis left attached medially/laterally, sutured to reinforce posterior wall - equivalent to Shouldice.

Open Mesh Repairs

• Lichtenstein tension-free mesh repair (1984): Flat polypropylene mesh (~8x15 cm) placed over the posterior wall behind the cord, slit around the cord at the deep ring. Most common operation for inguinal hernia in resource-rich countries. Lower recurrence but chronic pain reported in up to 20% is a major concern.
• Mesh plug/device: Shaped plugs - risk of meshoma, migration, erosion into bladder. Not recommended by 2018 European Hernia Society guidelines.
• Open preperitoneal (Stoppa): Mesh placed behind transversalis fascia via midline incision. Useful for recurrent hernia. Now largely superseded by TEP.

Laparoscopic Repairs

• TEP (Totally ExtraPeritoneal): Balloon dissection creates preperitoneal space; mesh (~10x15 cm) placed without entering the peritoneal cavity.
• TAPP (TransAbdominal PrePeritoneal): Peritoneal cavity entered, peritoneum incised, mesh placed preperitoneally.
• Both show lower rates of chronic pain and faster return to work than Lichtenstein. Preferred for bilateral and recurrent hernias.
• Robot-assisted laparoscopic repair is an emerging approach with similar outcomes.

7. FEMORAL HERNIA

Anatomy

• Laterally: Femoral vein
• Anteriorly: Inguinal ligament
• Posteriorly: Iliopectineal (Astley Cooper's) ligament
• Medially: Lacunar (Gimbernat's) ligament - this sharp, unyielding curved edge impedes reduction

Key Features

• Less common than inguinal hernia
• More common in women (wider femoral canal due to female pelvis shape)
• Appears below and lateral to the pubic tubercle (vs. inguinal hernia which is above and medial)
• Diagnostic error is common
• 50% present as emergencies with very high risk of strangulation - the rigid bony/ligamentous boundaries trap the content

Repair

8. VENTRAL HERNIAS

Umbilical Hernia

• Children: Occurs in ~10% of infants. 95% resolve spontaneously by age 2. Conservative management recommended under age 2 years. Surgery if persists beyond age 2. (Strangulation extremely rare under age 3)
• Adults: Re-opening of umbilical ring; associated with obesity, ascites, multiple pregnancies. Repair with suture or mesh depending on size.
• Surgery: Small curved infra-umbilical incision; sac identified, reduced, and closed; defect closed with interrupted slowly-absorbable sutures.

Epigastric Hernia

• Protrusion of extraperitoneal fat (and sometimes peritoneum) through defects in the linea alba between the xiphoid process and umbilicus
• Often multiple, frequently asymptomatic. May cause epigastric pain (entrapped fat)
• Treated surgically; suture repair for small defects

Spigelian Hernia

• Protrudes through the spigelian fascia (aponeurosis of transversus abdominis) at the lateral border of the rectus at the semilunar line
• Often interparietal/interstitial - no visible lump; presents with pain and high risk of strangulation
• Diagnosis often requires CT or US; treated surgically

Lumbar Hernia

• Protrudes through the lumbar triangles:
  • Superior lumbar triangle (Grynfeltt): Bounded by 12th rib, internal oblique, and sacrospinalis
  • Inferior lumbar triangle (Petit's): Bounded by iliac crest, latissimus dorsi, external oblique
• Rare; may be congenital or acquired (post-surgery/trauma)

Incisional Hernia

• Occurs in >10% of laparotomies; laparoscopic port sites ~1%
• Risk factors: wound infection, obesity, steroids, poor technique, excessive tension, diabetes
• May be large and complex, requiring mesh repair
• Often managed with component separation techniques or bridging mesh for giant hernias

Parastomal Hernia

• Hernia through the abdominal wall around a stoma (colostomy/ileostomy) site
• Very common; most do not require repair unless symptomatic or causing stoma dysfunction

9. Other Important Hernias

Hiatus Hernia

• Type I (Sliding): Gastro-oesophageal junction slides into the thorax through the oesophageal hiatus. Most common (~95%). Associated with GERD.
• Type II (Rolling/Para-oesophageal): Fundus rolls up into thorax while GEJ remains in normal position. Risk of gastric volvulus, strangulation.
• Type III: Mixed (both GEJ and fundus herniate)
• Type IV: Other organs (colon, spleen, small bowel) also herniate

Obturator Hernia

• Through the obturator foramen in elderly, multiparous, thin women
• Classic sign: Howship-Romberg sign - medial thigh pain aggravated by hip extension/abduction/internal rotation
• Usually presents as small bowel obstruction; preoperative diagnosis rare

Perineal Hernia

• Protrudes through the floor of the pelvis; usually post-abdominoperineal resection or pelvic floor weakness

Diaphragmatic Hernias

• Bochdalek: Posterior (pleuroperitoneal canal); commonest congenital diaphragmatic hernia; bowel herniates into left chest; presents at birth with respiratory distress
• Morgagni: Anterior (through foramen of Morgagni); usually asymptomatic, discovered incidentally

10. Complications of Hernia Repair

• Recurrence: Most common long-term complication. Rates: Bassini ~5-10%, Lichtenstein <1-2%, Shouldice <2% in expert centres, TEP/TAPP ~1%
• Chronic pain/neuralgia: Up to 20% with open mesh (ilioinguinal, iliohypogastric, genitofemoral nerve injury/entrapment)
• Wound infection/seroma: Fluid collection in the hernia sac remnant
• Injury to vas deferens / testicular atrophy: Rare; risk with recurrent surgery
• Mesh complications: Infection, migration (meshoma), erosion into bowel/bladder
• Urinary retention: Especially post-inguinal/femoral repair in elderly males
• Haematoma: Inguinal/scrotal blood collection

11. Key Surgical Mnemonics

NAILS - Necrosis, Abscess, Intestinal obstruction, Leak/fistula, Systemic sepsis

NAIL - Nerve (femoral, lateral), Artery, vein (Inside the sheath), Lymphatics (medially = canal content)

"My Precious Darling Dear" - Muscle of transversalis, Peritoneal sac, Ductus deferens, Deferent artery