Spigelian hernias are infrequently occurring hernias most commonly presenting in the 5th or 6th decades. These hernias are a protrusion of intra-abdominal contents through the Spigelian fascia, which is the aponeurotic tissue anatomically located at the junction of the semilunar line laterally and rectus abdominus medially.
The most precise description of the hernia location is at the junction of the linea semilunaris and linea semicircularis at the junction of the of the muscular and aponeurotic portions of the transverse abdominus. These hernias are almost always found below the arcuate line (semicircularis)
The most consistent symptom of a Spigelian hernia is pain, with a variable finding of a palpable hernia bulge. This is due to the hernia sac bulging throught the transverse abdominis and internal oblique muscles but remaining deep to the external oblique aponeurosis.
If Spigelian hernia is suspected clinically, a CT scan is usually obtained for definitive diagnosis. Laparoscopic repair has largely replaced open repair and is associated with lower morbidity and shorter length of stay.
Approximately 20% of Spigelian hernias are incarcerated upon diagnosis.