Mesenteric Venous Thrombosis

Excerpt

Mesenteric venous thrombosis is a clot within the superior or inferior mesenteric vein or its branches. Thrombosis may be secondary to an inherited or acquired thrombophilia or as a consequence of or in conjunction with a proinflammatory state. Factors contributing to mesenteric venous thrombus formation include injury, stasis, malignancy, infection, trauma, and systemic inflammation. While greater than 25% of cases of mesenteric venous thrombosis may initially appear idiopathic, with thorough evaluation, many are shown to have an identifiable etiology. The thrombosis can originate in the vena rectae or a major vein and may involve the portal vein. The superior mesenteric vein is involved in more than 90% of cases of mesenteric vein thrombosis, whereas the inferior mesenteric vein is only implicated in up to 11% of cases.

Mesenteric venous thrombosis may be an acute, subacute, or chronic process. Venous thrombi account for 5% to 15% of cases of acute mesenteric ischemia and are responsible for 1 in 5000 to 15,000 inpatient admissions and 1 in 1000 emergency department visits. Chronic mesenteric venous thrombosis accounts for 20% to 40% of all cases and is often an incidental finding. Although mesenteric venous thrombosis is a relatively rare condition, mortality remains high due to nonspecific symptoms and delayed diagnosis.

The location, acuity, and extent of the thrombus affect the prognosis. Patients with chronic thrombosis may have complications stemming from venous hypertension, including malnutrition and esophageal or gastric varices. Chronic thrombi promote the formation of collaterals that protect the bowel from ischemic changes, but when a thrombus arises acutely, mesenteric ischemia may develop quickly; acute ischemia disrupts the intestinal mucosal barrier, promoting bacterial translocation and resulting in sepsis, multisystem organ failure, and death.

Treatment of mesenteric venous thrombosis ranges from temporary anticoagulation with management of the underlying proinflammatory disorder to prolonged intensive care unit admission and urgent surgical intervention. The goal of treatment is to protect tissue, prevent the extension of the thrombosis, and minimize the chances of recurrence. Anticoagulation is often a mainstay of therapy. Anticoagulation is recommended even for those patients with varices, but patients with symptomatic varices may require decompression of their venous hypertension before they are anticoagulated.