S6143 An Unusual Cause of Gastric Outlet Obstruction: Superior Mesenteric Artery Pseudoaneurysm

Introduction: Visceral artery pseudoaneurysms (VAPAs) are rare, most commonly involving splenic, renal, or hepatic arteries. Pseudoaneurysms are a recognized complication of both acute and chronic pancreatitis. Superior mesenteric artery (SMA) pseudoaneurysms are particularly uncommon. Duodenal hematomas in adults are typically associated with trauma, coagulopathy, or pancreatitis. However, they can rarely result from spontaneous hemorrhage of a visceral pseudoaneurysm. Here, we present an unusual case of gastric outlet obstruction (GOO) due to a duodenal hematoma secondary to a pseudoaneurysm of the SMA, in the absence of gastrointestinal (GI) bleeding or trauma. Case Description/Methods: A 55-year-old man with history of alcohol-associated pancreatitis presented with 3 days of right-sided abdominal pain, nausea, vomiting, and inability to tolerate oral intake. He also reported a 10-pound weight loss over 6 months, recurrent nausea, and early satiety. There was no history of trauma. Examination revealed right upper quadrant tenderness. Hemoglobin was 13.2 g/dL, platelets 222 and INR 1.2. Abdominal computed tomography showed heterogeneous density in the duodenum. Magnetic resonance imaging obtained for further characterization revealed a 7.2 × 3.3 × 5.1 cm well-encapsulated fluid collection suggestive of a hematoma. Computed tomography angiography showed active hemorrhage, though there were no clinical signs of GI bleeding. Esophagogastroduodenoscopy showed retained gastric contents. After clearance, a large partially obstructive polypoid submucosal lesion with erythematous mucosa was seen in the duodenal bulb. Biopsies showed unremarkable mucosa. The second part of the duodenum and ampulla were normal. Given concerns for a vascular etiology, he underwent a mesenteric angiography with interventional radiology which identified a small pseudoaneurysm arising from an SMA branch. Multiple endovascular coils were deployed for successful embolization. The patient’s symptoms resolved post-procedure with improved oral intake. Discussion: This case is unique in both presentation and diagnosis, exemplifying a rare cause of GOO due to an SMA pseudoaneurysm. Pseudoaneurysm-related hemorrhage should be in the differential when submucosal duodenal lesions are encountered in association with hematomas, especially in patients with a history of pancreatitis. Early recognition of this rare but potentially life-threatening condition is essential, as a missed or delayed diagnosis may result in catastrophic hemorrhage.