Spigelian hernia

Spigelian hernia

These hernias are uncommon although probably underdiagnosed. They a ff ect men and women equally and are most common in elderly people. They have also been described in infants, reflecting incomplete di ff erentiation of through a defect in the aponeurosis of transversus abdominis (Spigelian fascia) and may advance through the internal oblique to spread out deep to the external oblique aponeurosis. Most Spigelian her nias appear below the level of the umbilicus near the edge of the rectus sheath, but they can be found anywhere along the Spigelian line ( Figure 64.22 ). There is a common misconception that they protrude below the arcuate line as a result of deficiency of the posterior rectus sheath at that level, but in fact the defect is almost always above the arcuate line. In young patients they usually contain extraperitoneal fat only , but in older patients there is often a peritoneal sac and they can become very large. Clinical features Y oung patients usually present with intermittent pain, due to pinching of the fat, similar to an epigastric hernia. A lump may or may not be palpable because the fatty hernia is small and the overlying external oblique is intact. Older patients generally present with a reducible swelling at the edge of the rectus sheath and may have symptoms of intermittent obstruction. The diagnosis should be suspected because of the location of the symptoms and is confirmed by CT . Ultrasonography has the advantage that it can be performed in the upright patient because no defect may be visible with the patient lying down. Treatment Surgery is recommended because the narrow and fibrous neck predisposes to strangulation. Surgery can be open or laparo - scopic. At open surgery a skin crease is made over the hernia, but no abnormality will be seen until the external oblique is opened. The sac and contents are dealt with and the small defect in the Spigelian fascia is repaired by suture or mesh laid deep to the external oblique aponeurosis . The plane of the mesh can be extended medially into the posterior rectus sheath if required. The external oblique aponeurosis is closed over the mesh. -

Figure 64.22 Spigelian hernia in the left iliac fossa. Note the scar from a previous left inguinal hernia repair.

patients with a hernia containing only extraperitoneal fat, no hernia will be seen from within the peritoneum. In such cases, the peritoneum can be incised and the extraperitoneal plane explored for the small defect, which can then be closed by either suture or mesh. When an intraperitoneal sac is present, laparo scopic repair can be performed using either the intraperitoneal onlay of mesh (IPOM) or, more commonly now because of the risks of intraperitoneal mesh, the TAPP technique. Summary box 64.15 Spigelian hernia /uni25CF /uni25CF /uni25CF

Rare Often misdiagnosed High risk of complications