Computed tomography of superior mesenteric vein thrombosis following appendectomy

During a 5-year period, superior mesenteric vein (SMV) thrombosis was detected with computed tomography (CT) in six patients shortly after an appendectomy. No sign of SMV was present at appendectomy, and a period of more than 2 weeks free of clinical symptoms had elapsed between the appendectomy and the onset of the SMV thrombosis. In four cases, the appendicitis was complicated. These patients had nonspecific signs and symptoms, although two of them had elevation of blood hepatic enzyme levels. In all cases, postcontrast CT demonstrated enlargement of the SMV, with well-defined enhancement of the vascular wall and an intraluminal clot. In one case, CT showed extension of the thrombus to the portal vein with the presence of low-attenuation areas in the liver, consistent with hepatic infarcts. Two patients had predisposing diseases: idiopathic hypersplenism in one case and chronic hepatic disease in the other. SMV thrombosis is a possible complication of appendicitis, and early appendectomy in appendicitis can prevent this complication. Moreover, as in any abdominal surgery, early appendectomy may be complicated by thrombosis of the SMV, thus creating problems of postoperative diagnosis. The complication is more frequent when the initial operation is performed under difficult conditions (peritonitis), or when the patient presents with a coagulopathy. CT is useful in the diagnosis of SMV thrombosis, thus leading to early management with anticoagulant therapy, with a view to avoiding complications such as intestinal ischemia, portal vein thrombosis, and hepatic infarction.