A case of portal hypertension due to a superior mesenteric arteriovenous fistula

Introduction: Superior mesenteric arteriovenous fistula (SMAVF) is an infrequent vascular disorder characterized by abnormal communication between high-pressure superior mesenteric artery and low-pressure superior mesenteric vein. This allows blood to bypass the intestinal capillary bed and produces portal hypertension leading to ascites and gastro-esophageal variceal bleeding. Although SMAVF can be congenital, most reported cases have been due to abdominal trauma or iatrogenic causes. Here, we report a case of SMAVF presenting as severe ascites.Case presentation: A 61-year-old female presented to the emergency department with a 1-week history of abdominal distention and discomfort. Her past medical history was significant for abdominal hysterectomy complicated by bowel resection. Initial evaluation was remarkable for severe hyponatremia and severe abdominal and pelvic ascites evidenced on computed tomography. A paracentesis was performed, fluid analysis was negative for spontaneous bacterial peritonitis. The Serum Ascites Albumin Gradient was elevated (>1.1 g/dL). The hospital course was complicated by gastrointestinal bleeding requiring blood transfusions. An upper endoscopy revealed bleeding esophageal varices that were banded. A magnetic resonance of the abdomen revealed a large SMAVF between causing increased portal vein blood flow and pressure; the patient subsequently underwent embolization of the SMAVF. The patient clinically improved and was discharged on stable condition. On follow-up after discharge, cross sectional imaging revealed improved appearance of the mesenteric vasculature and resolution of the ascites.Discussion: This case illustrates the for clinicians to be vigilant for rare but reversible causes of portal hypertension that can mimic cirrhosis in order to provide appropriate diagnosis and management.