Herniae

Herniae: Overview

A hernia is defined as a protrusion of a viscus or part of a viscus through a weakness in the wall of the containing cavity. It has an aperture, coverings (usually peritoneum and abdominal wall layers) and contents, which may be any intra-abdominal organ but are usually omentum or small bowel.

Surgical treatment requires reduction of the contents and closure of the aperture, with reinforcement to prevent recurrence.

There are a number of described sites for herniae. This entry will focus on the more common, but the principles of assessment and treatment apply in general to herniae at other sites as well.

1. Inguinal Hernia

Inguinal herniae are extremely common, with a lifetime risk of occurrence of 27% for men and 3% for women, and an annual incidence of 130 per 100 000 population. Up to 9% of hernia repairs are performed urgently. Emergency repairs are more common in the elderly and carry greater morbidity than elective repair.

As their name implies, direct inguinal herniae bulge directly through the posterior wall of the inguinal canal. They are caused by weak abdominal musculature, are common in the elderly, and frequently bilateral. They have a large neck and hence seldom become irreducible or strangulate until they are of considerable size.

For indirect inguinal herniae, the hernial sac comes through the internal inguinal ring, travels the length of the inguinal canal and emerges from the external inguinal ring. Thus it usually lies above and medial to the symphysis pubis.

Later the internal inguinal ring may stretch and the hernial sac and its contents may descend to and fill the scrotum, occasionally becoming very large. As the internal inguinal ring is usually narrow, irreducibility is common. Indirect inguinal herniae occur throughout life.

Direct and indirect inguinal hernia may be distinguishable by simple clinical tests. When an indirect hernia is reduced, finger pressure over the site of the internal ring may hold it reduced; however, a direct inguinal hernia will flop out again unless several fingers or the side of the hand props up the entire length of the inguinal canal.

2. Femoral Hernia

Femoral herniae appear lateral and inferior to the symphysis pubis. They are formed by the peritoneal sac and contents, which occupy the potential space of the femoral canal, medial to the femoral vein.

They are proportionately more common in women and rarely large. Symptoms usually occur early and complications are common.

The femoral canals should be closely examined in any patient presenting with abdominal pain or signs of bowel obstruction, as femoral hernia are frequently overlooked, especially in patients who are elderly and obese. Diagnosis of a femoral hernia mandates early surgery. Morbidity from emergency femoral hernia repair increases with the presence of small bowel obstruction Opens in new window, and mortality with emergency surgery can be as high as 5%.

3. Umbilical Hernia

Umbilical and periumbilical hernia protrude through and around the umbilicus. They are very common in the newborn, but most resolve by 4 years of age. As they have a broad neck, emergency complications are uncommon. They can be difficult to diagnose in very obese people. If complicated, they can present resembling abdominal wall cellulitis.

4. Epigastric Hernia

Epigastric herniae appear in the midline above the umbilicus. A small extraperitoneal piece of fat may be stuck in this hernia, causing pain.

Other Herniae

1. Obturator Hernia

Rarely, viscera may pass through a defect in the obturator foramen and present as a small bowel obstruction. This occurs most commonly in elderly emaciated women with chronic disease. Diagnosis of this internal hernia, and the hernia of the foramen of Winslow, is seldom made preoperatively.

2. Spigelian Hernia

These are and are due to a defect in the anterolateral abdominal wall musculature. They usually present as a reducible lump in the elderly male, lateral to the rectus muscle in the lower half of the abdomen. Complications are rare.

3. Incisional Hernia

These may occur at the site of any previous abdominal wound, such as appendicectomy or laparotomy. The wound area becomes weak, allowing the protrusion of a viscus or part of a viscus.

4. Sportsman’s (Athlete’s) Hernia

This is a term used for those who present with the painful symptoms of a hernia in the groin following exertion. It is defined as an occult hernia caused by weakness or tear of the posterior inguinal wall without a clinically recognizable hernia. Generally, by the time of diagnosis non-operative treatment options have failed and surgery often results in a return to sport. Ultra-sound can be a useful diagnostic medium to detect herniae which are intermittently symptomatic but without clinical signs.

Complications

In the early stages hernia are usually reducible, producing only intermittent pain in the groin, but reducible hernia may become irreducible (incarcerated). Incarcerated herniae may lead to a bowel obstruction. Strangulation and interruption of the blood supply to the contents of the hernia (usually small bowel) may supervene. In this case there will be increasing local pain and tenderness, warmth and overlying erythema accompanied by signs of bowel obstruction Opens in new window, accompanied by leukocytosis.

Rarely only part of the bowel wall is caught in a hernia constricting ring. Bowel wall necrosis ensues that is not circumferential; this is termed a Richter’s hernia. In this case, there may be signs of strangulation without signs of obstruction.

Very rarely, neglected herniae can fistulate, with bowel contents appearing at the abdominal wall or through the hernial orifices.

Treatment

1. Reduction

It may be possible to reduce a hernia that initially appears irreducible in the emergency department (ED), but caution must be exercised. If the skin over the hernia is already inflamed and pain is severe, the contents may be compromised and urgent surgical exploration is required. Reduction of the contents in this circumstance can be dangerous, as false reassurance can occur followed by the later development of peritornitis due to intra-abdominal perforation of the hernia contents.

As a general rule, if the hernia has been irreducible for less than 4 hours, vital signs are normal and there are no symptoms of bowel obstruction, reduction of an incarcerated hernia may be attempted. This is achieved by giving adequate analgesia to relax the patient and applying gentle pressure manipulating the hernia site for several minutes.

Elevating the foot of the bed may be helpful. Successful reduction relieves pain, may prevent strangulation and reduces the urgency for surgical intervention. Notwithstanding, all herniae that have undergone a complication require surgical consultation at the time of presentation.

2. Surgical Repair

Inguinal hernia repair is a very common operation in general surgery. Rates of repair range from 10 per 10 000 population in the UK to 28 per 10 000 in the USA.

Timely repair of herniae reduces the incidence of complications and avoids the greater risk associated with emergency surgery. Until the introduction of synthetic mesh, inguinal hernia repair had changed little for over 100 years. The mesh can be placed by an open method or laparoscopically.

Laparoscopic transabdominal preperitoneal hernia repair takes longer than open surgery and has a more serious complication rate with regard to visceral injuries, but is being increasingly performed as it reduces postoperative pain and significantly reduces time off work. It is also much more operator dependent, is more difficult to learn and has higher overall hospital costs.

Patients requiring emergency surgery for bowel obstruction or strangulation should be prepared with adequate fluid resuscitation and analgesia.