[A case of portal vein thrombosis associated with congenital protein S deficiency].

A 25-year-old man was admitted to our hospital because of abdominal pain, nausea and low-grade fever. An abdominal CT showed remarkable thickening of the wall of the small intestine and extensive thrombosis of the mesenteric, portal and splenic veins. Because neither intestinal infarction nor peritonitis was seen, anticoagulation therapy was chosen. Heparin was administered intravenously and was used alternatively with warfarin later. The patient's symptoms and clinical data improved gradually. Concerning the etiological factors of the thrombosis, only protein S activity definitely decreased. Genetic analysis indicated a variant of protein S, protein S Tokushima.