Case ii -  Ischemic Bowel

There segmental thickening of the colon from the ascending colon to the splenic flexure.  The transition from normal to abnormal bowel is abrupt.  There is subtle stranding and thickening of the fascia in the right lower quadrant.   There is also stranding around the transverse colon.  The generic differential diagnosis is infection, inflammation, and ischemia.  However, closer inspection shows portal air.  This branching air in the liver comes within millimeters of the liver capsule.  Pneumobilia is not seen this peripherally in the liver.  Even closer inspection shows air in mesenteric veins adjacent to the abnormal bowel.  These findings indicate ischemic and necrotic bowel.  The long segment of bowel, ending at the splenic flexure (where the area supplied by the SMA ends) is also consistent with ischemic bowel.  The patient went to surgery and a necrotic right and transverse colon were removed.

Findings of ischemic bowel are varied.  Pneumatosis, venous gas, and portal air are good indicators of ischemia.  Stranding is often subtle.  Wall thickening is variable.  Long segments of bowel are more common than short segments, and distributions should not cross vascular territories unless you are considering ischemia from hypotension.  Only very rarely will you see an acute thrombus in the artery or vein.