A Case of Loss of Consciousness Due to Thrombosis of the Inferior Vena Cava and Portal Vein

We present a case where intraperitoneal venous thrombosis was difficult to treat. It is difficult to suspect intraperitoneal venous thrombosis in patients who have visited the hospital due to loss of consciousness, and it is necessary to administer anticoagulants early for treatment and to determine the appropriate timing for surgical intervention. The patient was a 78-year-old male who independently performed his daily activities. On the day of admission, he lost consciousness and was brought to our hospital. Computed tomography (CT) angiography revealed thrombi from the inferior vena cava and portal vein to the superior mesenteric vein, and the patient was started on anticoagulant therapy. The CT angiography images on day 7 of the illness revealed that the thrombus in the superior mesenteric vein expanded to the caudal side. Intestinal necrosis occurred on day 22 of the illness, and emergency laparotomy was performed. The chosen course of treatment was successful, and the patient was discharged on the 48th day.