S4758 Jejunal Diverticulum With Arteriovenous Malformation Presenting as Obscure GI Bleeding in an Elderly Patient

Introduction: Small bowel bleeding, defined as hemorrhage occurring between the ampulla of Vater and the ileocecal valve, represents a rare cause of gastrointestinal bleeding, accounting for approximately 5–10% of cases. Diagnosing its source can be challenging, especially in elderly patients with multiple comorbidities, due to the difficulty of localizing the bleeding site using conventional studies. This case describes an unusual presentation of small bowel bleeding due to a jejunal diverticulum associated with an arteriovenous malformation (AVM). Case Description/Methods: An 81-year-old man with a history of hypertension, hiatal hernia, gastritis, coronary artery disease, and pandiverticulosis presented with melena, fatigue, weakness, and abdominal pain. Upper endoscopy and total colonoscopy were non-diagnostic. Capsule endoscopy revealed a suspected mass in the proximal jejunum with mucosal erosion and stigmata of bleeding, which was later interpreted as an inverted bleeding diverticulum based on surgical findings. Magnetic resonance enterography and antegrade enteroscopy were inconclusive. Due to clinical deterioration, the patient underwent diagnostic laparoscopy with intraoperative enteroscopy. This revealed multiple broad-based jejunal diverticula; 1 contained visible content, superficial mucosal erosions, and stigmata of recent bleeding. An AVM was identified and surgically resected. Histopathology confirmed pseudodiverticula with mucosal erosion and an AVM. The patient had an uneventful recovery. Discussion: This case illustrates a rare cause of small bowel bleeding due to the coexistence of a jejunal diverticulum and an arteriovenous malformation. Among the 8 similar cases reported, this case is notable for the use of a multi-modal diagnostic approach, including capsule endoscopy, magnetic resonance enterography, and surgical exploration. It emphasizes the importance of maintaining a high index of suspicion for rare etiologies in complex cases. The coexistence of diverticula and arteriovenous malformations is exceptionally rare. Even with advanced diagnostic tools, surgical intervention may be necessary for definitive management. This demonstrates the importance of a systematic diagnostic approach in elderly patients with unexplained gastrointestinal bleeding.