Solution to Unknown Case #39 – Pneumatosis Intestinalis with Pneumoperitoneum

Pneumatosis Intestinalis – Axial CT scan of the abdomen displayed in lung windows reveals air within the colon wall (yellow arrow). There is also a significant amount of pneumoperitoneum (red arrow).

This is a case of pneumatosis intestinalis with pneumoperitoneum. Pneumatosis intestinalis can be caused by many different entities. The most worrisome scenario is bowel ischemia. Small bowel ischemia is usually due to occlusion of either the superior mesenteric artery or superior mesenteric vein. Colonic ischemia is usually due to hypoperfusion.

This patient underwent subtotal colectomy. The final pathology confirmed pneumatosis intestinalis; however, the mucosa was intact and there was no evidence of bowel infarction. In retrospect, it was believed her pneumatosis intestinalis was caused by chronic lactulose use, which is known to be a medication that can cause pneumatosis. The mechanism behind lactulose involves altering the microbial environment in the colon to increase production of carbon dioxide gas and hydrogen gas which eventually distends the colon and diffuses into the wall of the colon.