Spigelian hernias, also known as spontaneous lateral ventral hernias or hernia of semilunar line, are rare. They only account for 2% of ventral hernias. They were first described by Adriann van der Spieghel in 1645. When small, they may only be apparent in the upright position, disappearing in the supine position.

The hernia sac often contains omentum and properitoneal fat, but may also contain small bowel or large colon. Incarceration rates are high for this type of hernia.

Ultrasound and CT are the modalities of choice for evaluation. CT offers excellent visualization of the abdominal wall defect and the contents of the hernia.