Case contributed by Bruno Di Muzio


Progressive pelvic pain for two days. Medical history of colonoscopy performed three days ago.

Patient Data

Age: 75 years
Gender: Female

CT Abdomen and pelvis (selected images)


Inflammation of the rectum characterized by surrounding fat stranding.

The multiple gas bubbles extending along the retroperitoneum confirms the origin of the perforation to be a retroperitoneal bowel segment, in this case, the rectum.

Small amount of pneumoperitoneum.

Annotated image

Gas bubbles dissecting along the retroperitoneum. Arrows indicate some of the retroperitoneal structures, such as the esophagus, kidney, aorta, psoas muscle, and rectum. 

Case Discussion

Pneumoretroperitoneum is by definition the presence of gas within the retroperitoneal space. It is always abnormal. 

The perforation may have occurred during the colonoscopy procedure. The most common site of colonic perforation is the rectosigmoid colon. 

A differential diagnosis to consider is complicated acute diverticulitis with perforation.

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