Portal Vein and Superior Mesenteric Vein Thrombosis in a Patient With Antiphospholipid Syndrome and Chronic Hepatitis B.

A 56-year-old woman with chronic hepatitis B presented with a two-year history of left-sided cramping abdominal pain and constipation. Contrast-enhanced CT (CECT) of the abdomen revealed an eccentric filling defect in the main portal vein extending into the superior mesenteric vein, causing significant narrowing of the cross-sectional area, thereby suggesting thrombosis. A thin eccentric filling defect was also observed in the inferior mesenteric vein. Anticardiolipin antibody IgM was positive, while the remainder of the thrombophilia workup was unremarkable. A diagnosis of antiphospholipid syndrome (APS) was considered, and the patient was started on anticoagulants. Portal or mesenteric vein thrombosis should prompt immediate evaluation for underlying prothrombotic conditions such as APS.