Incarcerated Spigelian hernia: ultrasonic differential diagnosis.

The gray scale ultrasonic findings in a case of incarcerated Spigelian hernia are presented. This hernia is uncommon, and the clinical diagnosis can be difficult. The appearance of the lesion is compared with others in and about the abdominal wall, including rectus sheath hematoma, seroma, abscess, peritoneal tumor implants, and pseudocyst at the end of a ventriculoperitoneal shunt. Clinical and sonographic differentiation is emphasized.