Ventral hernia is an umbrella term that includes several types of hernias occurring along the anterior abdominal wall. An umbilical hernia is a congenital defect of the umbilical fascia that is very common in childhood. The majority of these hernias close spontaneously by 2 years of age and surgical repair is usually not required. An epigastric hernia is also along the midline, but the fascial defect is located higher on the abdominal wall. Given this location, omentum and preperitoneal fat are the most common tissues to become incarcerated in an epigastric hernia. A Spigelian hernia occurs at the lateral border of the rectus muscle, at or below the arcuate line where the posterior rectus sheath is absent (Fig. 24.1). Spigelian hernias are difficult to diagnose since the hernia sac may lie between muscle layers, and therefore there may be no discernable mass on physical exam (Fig. 24.2). A rectus diastasis is not truly a hernia; it describes an acquired thinning and widening of the linea alba, which allows the abdominal contents to protrude outward. Since there is no fascial defect, on physical exam the bulge has no discernable edges.

An incisional hernia is a hernia through a prior surgical site that occurs when the fascia does not heal properly (Fig. 24.3a). Incisional hernias may be the result of a technical failure, such as poor closure technique and excessive tension. However, even properly closed wounds can result in a postoperative hernia if the fascia is compromised by a wound infection. Since, by definition, incisional hernias involve prior surgery, their repair is often complicated by the presence of intra-abdominal adhesions. The repair of an incisional hernia may require an extensive lysis of adhesions before the hernia repair can begin.

The main reason to repair a hernia is to prevent the chance of incarceration or strangulation. Another important reason to perform herniorrhaphy is to prevent progression of the hernia. The constant pressure exerted by the intra-abdominal organs leads to gradual enlargement of the hernia defect. In extreme cases, the entire bowel and other intra-abdominal organs can herniate out the fascial defect. The abdominal cavity gradually contracts, and eventually can no longer contain all the abdominal contents—a phenomenon known as loss of domain. Sudden replacement of the viscera back into the abdomen at the time of hernia repair can lead to excessive tension and compartment syndrome. Therefore, giant hernias present a surgical challenge that often requires complex repair including abdominal relaxing incisions and large pieces of mesh.

A clinically important type of hernia, known as a Richter’s hernia, occurs when only a small portion of the bowel wall is incarcerated within a fascial defect. Since the lumen of the bowel remains open, a patient with a Richter’s hernia will not develop bowel obstruction. However, the portion of bowel wall that is trapped within the hernia can go on to become ischemic and necrotic, leading to perforation and abdominal sepsis. A delay in diagnosis often occurs in these cases since patients do not present with the typical obstructive symptoms or an obvious hernia mass on exam. Thus, a high level of suspicion is required to diagnose a Richter’s hernia before strangulation occurs.