hernia

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Here is a comprehensive overview of hernias.

Hernia — Clinical Overview

Definition

A hernia is the protrusion of an organ or tissue through an abnormal opening in the wall that normally contains it. Most abdominal hernias consist of a sac (peritoneal outpouching), a neck (the opening through which content protrudes), and contents (bowel, omentum, or other viscera).

Classification

By Reducibility

State	Definition
Reducible	Contents can be returned to their normal position spontaneously or manually
Incarcerated	Contents cannot be reduced; does not imply ischemia
Strangulated	Blood supply is compromised — a surgical emergency

Smaller hernial necks carry a disproportionately higher risk of strangulation. Up to 40% of femoral hernias are strangulated at initial presentation, compared with only 2% of incisional hernias. — Sleisenger & Fordtran's GI and Liver Disease

By Origin

Congenital — patent processus vaginalis (indirect inguinal), omphalocele, umbilical
Acquired — direct inguinal, incisional, hiatal (from raised intra-abdominal pressure, aging, obesity)

Anatomical Locations

Hernia sites on the anterior abdominal wall — epigastric, umbilical, Spigelian, inguinal, femoral, obturator

Anterior abdominal wall hernia locations — Bailey & Love's Surgery, 28th ed., p. 1086

Major Types

1. Indirect Inguinal Hernia ← Most common overall

Passes through the deep (internal) inguinal ring, travels the inguinal canal, and may descend into the scrotum
Located lateral to the inferior epigastric vessels
Caused by a patent processus vaginalis (congenital); ~5% of full-term neonates, ~30% of preterm infants are affected
Predominates in males and is most commonly diagnosed in children and young adults

Indirect inguinal hernia — small intestine through deep inguinal ring, inguinal canal, and into hernial sac in scrotum

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

2. Direct Inguinal Hernia

Protrudes directly through the posterior wall of the inguinal canal (Hesselbach's triangle), medial to the inferior epigastric vessels
Acquired — caused by progressive weakening from aging and repetitive increases in intra-abdominal pressure
Wide neck → lower risk of incarceration than indirect hernias

3. Pantaloon Hernia

A combination of both direct and indirect components straddling the inferior epigastric vessels
Often only discovered at surgery; difficult to sustain reduction in the ED

4. Femoral Hernia

Passes through the femoral canal, below and lateral to the pubic tubercle, medial to the femoral vessels
More common in females (especially multiparous)
High risk of strangulation (up to 40% at presentation) due to the rigid, narrow femoral ring

5. Umbilical Hernia

Protrusion through the umbilical ring
Common in neonates (usually closes spontaneously by age 3–5); in adults it is acquired (obesity, ascites, pregnancy)
Accounts for ~15% of emergency hernia surgery; up to 60% of these show strangulation at operation

6. Epigastric Hernia

Protrusion through the linea alba between the xiphoid and umbilicus
Usually contains pre-peritoneal fat; may be painful out of proportion to size

7. Spigelian Hernia

Occurs along the semilunar line (lateral edge of the rectus sheath), typically below the arcuate line
Interparietal — lies beneath the external oblique → may be occult on examination but symptomatic

8. Incisional Hernia

Through a prior surgical wound; lifetime risk after laparotomy ~10–15%
Wide neck → low rate of strangulation (~2%), but large size can cause morbidity

9. Hiatal Hernia

Stomach herniates through the diaphragmatic hiatus into the chest
Type I (sliding): GEJ migrates superiorly — most common (~95%), associated with GERD
Type II (paraesophageal): fundus herniates with GEJ in normal position
Types III & IV: mixed / giant, with other organs (colon, spleen) involved

10. Internal Hernias

Herniation into a peritoneal recess or through a mesenteric defect; most commonly paraduodenal (congenital) or iatrogenic (after Roux-en-Y bypass, colectomy, Whipple procedure)

Clinical Presentation

Feature	Classic finding
Groin/abdominal bulge	Worse on standing/straining; reduces on lying down
Pain/discomfort	Dragging ache; sharp pain suggests incarceration
Nausea/vomiting	Suggests obstruction from incarcerated bowel
Skin erythema, fever	Suggests strangulation — emergency

Cough impulse (visible or palpable expansion on coughing) is a classic sign. Absence does not exclude hernia.

In obese patients, incarceration can be difficult to identify clinically; CT is often required.

Complications

Incarceration → bowel obstruction — hernia accounts for up to 44.5% of small bowel obstruction operations in some series
Strangulation → ischemia (in up to 75% of hernia-related SBO surgeries) → necrosis (>25%) → perforation → peritonitis
Obstruction of other structures: bladder (inguinal), ovary/fallopian tube (inguinal in females), ureter

Management

Watchful Waiting

Appropriate for minimally symptomatic or asymptomatic inguinal hernias in adults. Evidence shows increased morbidity with emergency vs. elective repair, so timely referral remains important.

Surgery — Indications

Symptomatic hernias
Incarcerated hernia (urgent)
Strangulation (emergency)
Femoral hernias (always repair given high strangulation risk)

Surgical Approaches

Technique	Key features
Open Lichtenstein (tension-free mesh)	Gold standard for inguinal; low recurrence (~1%)
Laparoscopic TAPP (Transabdominal Preperitoneal)	Mesh via laparoscope; good for bilateral/recurrent
Laparoscopic TEP (Totally Extraperitoneal)	No peritoneal entry; reduced intraperitoneal risk
Open tissue repair (Shouldice, Bassini)	Reserved where mesh is contraindicated (infection)
Emergency repair	Bowel resection may be required if strangulated

Manual reduction of an incarcerated hernia may be attempted when strangulation is not suspected; contraindicated if there is severe tenderness, skin erythema, or systemic signs — these mandate urgent operative exploration.

Key Risk Factors

Male sex (inguinal), female sex (femoral)
Prematurity (indirect inguinal)
Obesity, chronic straining (constipation, COPD, heavy lifting)
Prior abdominal surgery (incisional)
Ascites, pregnancy (umbilical)
Connective tissue disorders (Marfan, Ehlers-Danlos)

Sources: Roberts & Hedges' Clinical Procedures in Emergency Medicine; Sleisenger & Fordtran's GI and Liver Disease; Bailey & Love's Short Practice of Surgery, 28th ed.

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