Here is an interesting CT abdomen in a middle-aged patient with 10 days of left lower quadrant pain and fevers:
This patient has an 8cm abscess from perforated diverticulitis.
In the center of the image you can see a large air and fluid filled cavity with surrounding fat stranding. This is consistent with an intraperitoneal abscess. In middle-aged and elderly patients diverticulitis is a very common cause of intraabdominal abscess. Other causes include perforated appendicitis, post-surgical infection, inflammatory bowel disease, surgical site anastomotic leak, perforated peptic ulcer, gangrenous cholecystitis, mesenteric ischemia with perforation, and pancreatic abscess.
Abscesses on CT have several classic features:
1. Heterogeneous contents including various densities of fluid and debris with gas formation
2. Rim enhancement with IV contrast due to high blood flow to the structure
3. Surrounding inflammation seen as fat stranding
Radiology usually likes oral contrast if you suspect an intraabominal abscess because it helps distinguish abscess cavities from surrounding loops of bowel. If you are studying abscesses in soft tissues or organs such as the liver, oral contrast is unnecessary.
Author: Russell Jones, MD