Appendix abscess Appendix abscess. This contrast-enhanced CT shows a large fluid-filled abscess (arrows) in the right iliac fossa, which was caused by perforated appendicitis. The abscess was drained percutaneously in Interventional Radiology. Related Case Studies Free intraperitoneal gas – CT Appendicolith Acute appendicitis – US Acute Appendicitis Crohn Disease – Barium Follow Through Acute Diverticulitis