Description

Answers
1. First attendance, portal venous phase CT examination of the abdomen. There is gas in the liver, centrally and with little branching. These are features of gas within the biliary tree, a usually benign feature seen: After ERCP and particularly after sphincterotomy After passage of a gallstone With chronic pancreatitis After biliary-enteric surgical anastomosis or fistula Rarely in cholangitis Also there is extensive calcification of the abdominal aorta.

2. Same patient, later attendance, portal venous phase CT examination of the abdomen. There is gas in the liver, peripherally and finely branching biliary tree. These are features of gas within the portal venous system, a usually grave finding seen: In small bowel infarction Necrotic or ulcerated colorectal carcinoma Diverticulitis Ulcerative Colitis After upper or lower GI endoscopy (in which context it is less concerning)

3. Same patient, same attendance as image 2, portal venous phase CT examination of the abdomen. There is gas in the bowel wall – pneumatosis intestinalis (PI). In the context of acute abdominal pain, this is consistent with small bowel infarction.

PI is a radiological finding. It can be idiopathic when it is referred to as primary PI, and tends to consist of microvesicles (10-100 mm cysts or bubbles within the lamina propria). Secondary PI is found in COPD, as well as obstructive and necrotic bowel disease, where the finding of linear streaks of gas parallel to the bowel wall help differentiate from primary PI.

4. Same patient, same level as image 3. Portal venous phase CT examination of the abdomen, lung window. Lung window settings make
identification of bowel wall gas much easier.