Retroperitoneal abscess cured by percutaneous drainage with ultrasonography.

This report presents an unusual case of an extensive retroperitoneal abscess caused by appendicitis in a child. A 3-year-old boy who presented with right lower abdominal pain and a high fever was found, by abdominal ultrasonography (US) and computed tomography (CT), to have a retroperitoneal abscess. Percutaneous drainage of the abscess under US guidance was successfully performed. There was no sign of recurrence of appendicitis or the abscess 12 months after the drainage.