Teaching Case

The patient presented with a 10 year history of right lower quadrant tenderness associated with intermittent abdominal pain, constipation and weakness. Physical examination showed a mildly obese woman with a 4x3 cm painless mass of the right lower abdomen. Plain radiography of the abdomen, ultrasonography, and computed tomography were performed.

10 year history of right lower quadrant tenderness associated with intermittent abdominal pain, constipation and weakness. Physical examination showed a mildly obese woman with a 4x3 cm painless mass of the right lower abdomen. Plain radiography of the abdomen, ultrasonography, and computed tomography were performed. Surgery revealed a peritoneal sac containing mesenteric fat and non ischemic small bowel loops trapped in a fascial defect protruding between two abdominal wall layers, characteristic for Spigelian hernia.

Spigelian hernia or spontaneous ventrolateral hernia is an uncommonly diagnosed hernia. Inferior to the umbilicus, there is a thinning of the posterior rectus sheath and variable separation of the musculo-aponeurotic bands of the transverse abdominal and internal oblique muscles creating potential parallel slitlike defects. In 95% the herniation protudes through these defects. It always contains a peritoneal sac, and rarely reaches a diameter of more than 2 to 3 cm. Anteriorly the hernia is usually covered by the aponeurosis of the external oblique muscle. In less than 5% the hernial sac also penetrates the latter aponeurosis and will be located subcutaneously. Spigelian hernia generally occurs during midlife. The incidence is not known. Both sexes are equally affected. These hernias are difficult to diagnose clinically. However, cross-sectional imaging techniques (ultrasonography and CT) will easily detect a Spigelian hernia and differentiate it from other abdominal wall masses, such as tumors, abscesses, lipomas, sebaceous cysts and spontaneous hematomas.