Portomesenteric venous thrombosis associated with rectal venous malformations

We report thrombosis of portal and mesenteric veins in patients with a pattern of rectal venous malformations (VMs) and ectatic major mesenteric veins.

Eight patients having rectal VMs with either ectatic mesenteric veins and/or evidence of portomesenteric venous thrombosis (PVT), evaluated from 1995-2009, were reviewed.

Portomesenteric venous thrombosis was evident in 5 patients at presentation. Three had patent ectatic mesenteric veins, 2 with demonstrated reversal of flow, and 2 of whom went on to thrombosis during observation. Six patients developed portal hypertension. Five remain on long-term anticoagulation. After recognizing this pattern, one patient underwent preemptive proximal ligation of the inferior mesenteric vein (IMV) to enhance antegrade portal vein flow and prevent propagation or embolization of venous thrombus from the IMV to the portal vein.

Rectal VMs should be evaluated for associated ectatic mesenteric veins. The ectatic vein siphons flow from the portal vein down to the rectal VM, leading to stagnation of blood in the portal vein and resultant thrombosis. Primary thrombosis in the stagnant rectal VM and/or mesenteric vein can also predispose to embolization up into the portal vein. This pattern of rectal VM and ectatic mesenteric vein should be considered a risk factor for devastating PVT.