An Unusual Case of Air in the Inferior Mesenteric Vein

Clinical History

A 48-year-old man was admitted with a 1-week history of pain in the left lower abdomen, constipation and fever. Physical examination demonstrated abdominal tenderness in the left lower abdomen. Upon laboratory evaluation, the white blood cell count was elevated, as was the C-reactive protein level.

Imaging Findings

Contrast-enhanced CT of the abdomen and pelvis demonstrated sigmoid diverticulosis, inflammatory wall thickening of the sigmoid colon and fat stranding in the sigmoid mesocolon. Furthermore, there was thickening of the wall of the inferior mesenteric vein with streaking densities within the perivascular fat. Moreover, tubular-shaped gas accumulation in the inferior mesenteric vein branches was noted. There was no gas in the portal veins. The presumed diagnosis of sigmoid diverticulitis with associated inferior mesenteric venous thrombophlebitis was made.

Subsequent treatment with IV antibiotics (amoxicillin/clavulanic acid), liquid diet and analgesics was initiated. The patient’s abnormal laboratory findings and clinical symptoms resolved within a week.

Discussion

Diverticulitis complicated by septic thrombophlebitis of the inferior mesenteric vein is rarely seen [1, 2]. Findings on CT consist of thickening of the vein wall, inflammation of the perivascular fat and intravenous tubular-shaped gas. When CT demonstrates (porto)mesenteric vein gas, differential diagnosis should be made with mesenteric ischemia [1].
Gas in the mesenteric veins resulting from thrombophlebitis can easily be seen on CT. When small mesenteric veins are involved, tubular or branched areas of decreased attenuation in the mesenteric border of the bowel may be visualized. It is important to recognize the combination of diverticulitis with mesenteric vein gas because of its predisposition to form hepatic abscesses. Hepatic abscesses are predominantly seen in the left lobe of the liver due to the laminar flow in the portomesenteric venous system [1]. When synchronous hepatic abscesses are present, (porto)mesenteric vein gas is associated with a poor prognosis [1].
The (porto)mesenteric vein gas associated with diverticulitis would result from gas-forming bacteria or a direct communication between the intestinal lumen and the mesenteric vein due to a necrotizing vasculitis in the bowel wall [1, 3].
In our case, septic thrombophlebitis was limited to the inferior mesenteric vein and could be treated conservatively. The indication for surgery depends on the underlying cause of the (porto)mesenteric vein gas [1].

Differential Diagnosis List

Final Diagnosis

Sigmoid diverticulitis with associated inferior mesenteric venous thrombophlebitis

URL:	https://www.eurorad.org/case/13107
DOI:	10.1594/EURORAD/CASE.13107
ISSN:	1563-4086