5 Hernias

Questions

A hernia is an abnormal protrusion usually of a viscus through its containing cavity wall (Fig. 3.5.1). Abdominal hernias are formed from peritoneum and may contain loops of bowel. The four most common types of hernia in adults are inguinal, femoral, umbilical and incisional.

Fig. 3.5.1 Landmarks of hernia bumps and groin pulses (see Fig. 3.24.2 for more detail).

Pathology

In infants, hernias are almost always caused by a patent process vaginalis in boys (9:1), leading to indirect inguinal hernias. In children, hernias occur because of developmental weaknesses in the abdominal wall. In adults, chronically raised abdominal pressure can cause hernias (obesity, straining, a single event such as lifting something heavy). Hernias are classified as reducible — can be pushed back into the containing sac (most commonly the abdomen), such as a reducible indirect inguinal hernia, or irreducible — cannot be pushed back into the abdominal cavity, thus predisposing to obstruction.

As hernias enlarge and adhesions form, complete reduction is less likely.

Inguinal hernias (direct and indirect) occur above and medial to the pubic tubercle (Fig. 3.5.2) and are more common in men. An indirect inguinal hernia arises through the deep ring, passes down the inguinal canal and protrudes through the superficial ring. It can be controlled by finger pressure over the deep ring (Ch. 33). These hernias result from congenital defects, regardless of age. A direct inguinal hernia arises straight through a defect in the posterior wall and then protrudes into the inguinal canal. These cannot be controlled by pressure over the deep ring. They result from weaknesses in the abdominal wall and are, therefore, more common in older patients. A scrotal hernia is an indirect inguinal hernia that continues down through the spermatic cord into the scrotum. A pantaloon hernia occurs when indirect and direct hernia occur together and are seen to ‘straddle’ the inferior epigastric vessels.