A hernia is the abnormal protrusion of an organ or tissue (usually abdominal contents) through a weakened area or defect in the walls of its containing cavity, most commonly the abdominal wall.
Anatomical Composition of a Hernia
A hernia comprises three components:
- Hernial Sac
- A pouch of peritoneum containing the herniated contents.
- Subdivided into:
- Mouth : Point of entrance.
- Neck : Junction of sac and abdominal cavity (site prone to strangulation).
- Body and Fundus : Extent of the sac.
- Coverings
- Derived from layers of the abdominal wall through which the sac protrudes.
- In chronic cases, these layers thin and lose distinctness.
- Contents
- Omentum : Omentocele.
- Small or large intestine : Enterocele.
- Part of the bowel wall : Richter’s hernia.
- Meckel’s diverticulum : Littre’s hernia.
- Bladder : Sliding hernia component.
- Ovary ± fallopian tube (especially in females).
- Fluid (e.g., ascitic fluid).
Types of Hernias by Reducibility and Complication
| Type | Description |
|---|---|
| Reducible | Hernia returns spontaneously or with manipulation. Positive expansile cough impulse . |
| Irreducible | Contents cannot be returned; no ischemia. Often due to adhesions or tight neck. |
| Obstructed | Intestinal obstruction present without ischemia. Risk of progression to strangulation. |
| Incarcerated | Entrapped bowel with fecal impaction; palpable putty-like mass. |
| Strangulated | Compromised blood supply → ischemia → necrosis within hours. A surgical emergency . Most common in femoral hernias. |
Common Causes and Risk Factors
- Increased intra-abdominal pressure : Chronic cough, constipation, urinary obstruction.
- Heavy lifting or straining.
- Obesity .
- Previous abdominal surgery (incisional hernia).
- Congenital defects .
Pathophysiology of Strangulation
- Initial venous obstruction causes congestion and transudate into the sac.
- Progression to arterial compromise leads to ischemia, mucosal necrosis, and gangrene .
- Fibrinous exudate dulls serosal shine.
- Bacterial translocation and infection ensue.
- Perforation leads to peritonitis and sepsis.
Clinical Presentation
Uncomplicated (Reducible) Hernia:
- Intermittent bulge that increases with coughing or standing.
- Non-tender, reducible swelling with positive cough impulse.
Complicated (Strangulated/Obstructed) Hernia:
- Sudden severe pain at the hernia site → colicky abdominal pain.
- Nausea, vomiting , abdominal distension.
- Tender, tense, irreducible mass .
- Absent bowel sounds (late ileus).
- No cough impulse .
- Skin changes (erythema) over the hernia suggest ischemia.
- Spontaneous relief of pain may indicate perforation , not resolution.
Diagnostic Evaluation
- Clinical examination : Key to diagnosis.
- Ultrasound : Useful for detecting occult hernias.
- CT scan : Highly sensitive; detects complications (strangulation, bowel obstruction).
- X-rays : May show bowel obstruction.
Management Principles
General Measures:
- Manual reduction : In uncomplicated, reducible hernias.
- Surgical repair (herniorrhaphy/herniorrhaphy + mesh) : Definitive treatment.
Emergency Surgery Indications:
- Strangulated or obstructed hernia.
- Necrotic bowel may require resection and anastomosis .
Postoperative Considerations:
- Avoid heavy lifting, treat cough/constipation to prevent recurrence.
- Mesh repairs (e.g., Lichtenstein tension-free repair) reduce recurrence risk.
High-Yield Notes
- Femoral hernias are more prone to strangulation than inguinal hernias .
- Richter’s hernia may strangulate without obstruction.
- Indirect inguinal hernias pass through the deep inguinal ring; common in young males.
- Direct inguinal hernias are acquired; through Hesselbach's triangle.
