SMV thrombosis with small bowel loops ischemia

Case contributed by Mohamed Mahmoud Elthokapy
Diagnosis certain


Severe abdominal pain and vomiting not relieved by medications.

Patient Data

Age: 40 years
Gender: Male

Distended superior mesenteric vein with heterogenous thrombus propagating to the portal vein with no flow detected inside.

Portal vein divisions filling defects (thrombus). 

Diffuse symmetrical mural wall thickening of segmental bowel loops having rosette appearance "suggesting small bowel" with aperistalsis on the dynamic study.

Preserved gut signature of the involved bowel loops with no significant free fluid around (unlike in perforation).

Echogenic surrounding mesenteric fat.

A cluster of dilated bowel loops mainly at the left abdominal side.

No air under the diaphragm.

CT with contrast


Non-enhanced portal vein and its two main divisions are consistent with portal vein thrombosis. Portal cavernoma (collaterals) is noted at the porta hepatis. 

Non-enhanced superior mesenteric and splenic veins are consistent with venous thrombosis.

A small bowel loop (likely jejunal) is seen at the right side of the abdomen shows marked circumferential hypoenhancing mural thickening with surrounding mesenteric edema and congested mesenteric venous collaterals consistent with segmental small bowel venous ischemia.

Global mesenteric fat edema and prominent mesenteric venous collateral.

Minimal fluid is seen in the pelvis.

Incidental mild mesenteric twisting is seen at the right upper abdomen best seen in the axial plane likely due to the bowel rotation anomaly spectrum.  

The condition passed conservatively on anticoagulant therapy with no interventional done at once. 

Case Discussion

The patient presented with severe abdominal pain and no characteristic certain differential and so, triphasic CT abdomen was done. The portal venous phase series (shown) shows occlusion of the superior mesenteric vein (SMV), splenic vein, and propagating to the portal vein as well as its divisions with early signs of bowel ischemia manifested by thickened edematous hypoenhancing walls.

Superior mesenteric vein thrombosis is one of the less common causes of acute mesenteric ischemia. Despite thrombosis of the SMV, small bowel necrosis is less likely to occur, presumably due to persistent arterial supply and some venous drainage via collaterals. Acute thrombosis may be difficult to detect in non-contrast studies or at the arterial phase as the thrombus may be iso- or hypodense and not usually hyperdense. The diagnosis is made on portal venous phase contrast-enhanced studies.

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