A 65-year-old woman with metastatic adenocarcinoma of the colon was undergoing chemotherapy following a colectomy and a hepatic wedge resection. The physical examination and laboratory data were unremarkable. The CT scan revealed an enlarged superior mesenteric vein with a central low density surrounded by a peripheral rim of thrombosis (arrow). Asymptomatic superior mesenteric vein thrombosis was diagnosed by Drs Jayaram Bharadwaj, Vineeta Baranos, Rakesh Shrivastava, Michael DiSalle, David Wolf, and James Haley of Rochester, NY. Superior mesenteric vein thrombosis can present as either a catastrophic clinical picture or, as in this patient, a chronic asymptomatic condition. Common predisposing conditions are hypercoagulable states; malignancies; trauma; inflammatory conditions, including abscess and pancreatitis; splenectomy; splenomegaly; variceal sclerotherapy; sickle-cell disease; decompression syndrome; and paroxysmal nocturnal hemoglobinuria. About 4% to 5% of all superior mesenteric vein thromboses are attributed to estrogencontaining oral contraceptives; between 25% and 50% of patients may lack an obvious predisposing condition.1 The most common symptom is nonspecific abdominal pain that is out of proportion to the physical findings. 2 Nausea, vomiting, diarrhea, hematemesis, and hematochezia also are manifestations. About 50% of these patients have occult blood in the stool. Abdominal tenderness, decreased bowel sounds, and abdominal distention are the most frequent findings. A large amount of fluid sequestration may be present. Colonic involvement and intestinal infarction are rare because of collateral circulation. Gangrene, perforation, and peritonitis occur only when there is total occlusion. Portal hypertension and variceal bleeding can develop in patients with long-standing asymptomatic superior mesenteric vein thrombosis. Frank peritonitis signifies terminal disease. After ruling out more common diseases, suspect superior mesenteric vein thrombosis in patients with predisposing conditions. The diagnostic modality of choice—abdominal CT scan with intravenous contrast—detects this condition in the majority of patients and delineates the extent of the thrombus. MRI is sensitive, does not expose patients to radiation, and can be used in those who are allergic to intravenous contrast medium; however, this modality is expensive and not widely available.3 Superior mesenteric vein thrombosis may be an incidental finding on an abdominal ultrasound scan obtained for other reasons. If the index of suspicion is high and the CT scan is negative, angiography may be helpful. Nonsurgical management includes administration of intravenous fluids, nasogastric decompression, and anticoagulation with heparin.4 Aggressive fluid management is essential because of the potential for massive fluid sequestration. Antibiotics are indicated when bowel perforation or peritonitis is suspected; prophylactic use of antibiotics is controversial. Surgery is required for intestinal infarction, gangrene, and peritonitis. Thrombolytic therapy may have a role, but potential GI bleeding, such as variceal bleeding, can be significant and life-threatening. Transjugular mechanical thrombolysis has been performed. Thrombectomy is useful for recent (between 1 and 3 days) proximal superior mesenteric vein thrombosis. Lifelong anticoagulation therapy is recommended. Despite this regimen, recurrence remains common; the long-term prognosis for these patients is poor. Variceal hemorrhage also may develop. This patient was treated with heparin followed by warfarin. She was discharged from the hospital and followed as an outpatient.
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