Antiphospholipid Syndrome Presenting as Thrombotic Acute Mesenteric Ischemia of an Anomalous Inferior Mesenteric Vein

Abstract

Introduction: Thrombosis of the splanchnic circulationis an uncommon manifestation of Antiphospholipid Syndrome (APS); a rare site of which is the Inferior Mesenteric Vein (IMV). The rarest etiology of Acute Mesenteric Ischemia (AMI) is thrombosis of the venous supply (2-5%). We present a case of a patient found to have APS presenting with AMI of the left colon secondary to thrombosis of an anomalous IMV. Case Report: A 76 y/o female presented with bright red blood per rectum, mild abdominal pain and tenderness with no rigidity or guarding. Investigations revealed nonspecific rectal and distal sigmoid inflammatory process on non-contrast CT. A flexible sigmoidoscopy revealed multiple ulcers in the rectum and sigmoid colon, with congested mucosa and exudates. Proximally the descending colon mucosa gradually normalized in appearance with a clear marginal zone which was suspicious for an ischemic etiology (Figure 1). An abdominal angiogram revealed multiple filling defects in a dilated IMV abnormally draining into the Superior Mesenteric Vein (SMV) with significant wall thickening of the left colon (Figure 2). Intravenous heparin drip was initiated. A rapid improvement in symptoms was observed. An anti-phospholipid antibody panel showed an increase in IgA anti β2- glycoprotein, confirming APS. The patient was bridged to Rivaroxiban. A re-evaluation after six months revealed no recurrence of symptoms. A follow up Colonoscopy showed normal mucosa of the colon with complete resolution of mucosal ischemic changes (Figure 3).Figure 1Figure 2Figure 3Discussion: APS presented itself with thrombosis in the least common location within the splanchnic circulation in our patient. The most common site of all- cause splanchnic thrombosis is the SMV (50 to 82%) and rarely involves the IMV (14%). Our patient has an anomaly by which the IMV drains into the SMV (normally drains into the splenic vein) which may explain the rarity of the location of her thrombosis and left colonic pathology. The early detection of our patient's thrombosis and early intervention with anticoagulation therapy was essential in avoiding bowel wall necrosis and the need for surgical intervention. Our experience with managing this patient highlights the benefits of maintaining a high level of suspicion for thrombosis of the splanchnic circulation in patients presenting with abdominal pain and blood per rectum.