S3309 Duodenal Fistula Secondary to Infected Pancreatic Pseudocyst: A Case Managed Conservatively

Introduction: Pancreatic fistulas represent abnormal connections between the pancreas and adjacent organs or spaces, most frequently arising as complications of severe pancreatitis or ruptured pseudocysts. They may involve the gastrointestinal tract (pancreatogastric, pancreatocolonic, or pancreaticoduodenal), pleural, or peritoneal cavities. Duodenal fistulization is relatively uncommon, accounting for less than 2% of cases associated with pseudocysts. Here, we present an elderly patient with multiple comorbidities who developed a duodenal fistula secondary to an infected pancreatic pseudocyst after acute pancreatitis. Case Description/Methods: A 77-year-old man with coronary artery disease, chronic kidney disease, diabetes, and a recent episode of acute pancreatitis (August 2024) underwent outpatient esophagogastroduodenoscopy (EGD) and endoscopic ultrasound (EUS) 6 weeks post-pancreatitis due to persistent poor appetite and a 58-pound weight loss. Endoscopy revealed a medium-sized fistula in the second portion of the duodenum, draining purulent material. Computed tomography abdomen demonstrated a thick-walled fluid collection (6.5 × 5.2 × 5.7 cm) with gas and surrounding duodenal inflammation, consistent with an infected pancreatic pseudocyst with fistulization. The patient denied experiencing fever or abdominal pain, remained hemodynamically stable, and showed no leukocytosis; however, inflammatory markers, such as C-reactive protein and erythrocyte sedimentation rate, were elevated. He was managed with intravenous antibiotics and later transitioned to oral. Surgery was consulted, but no intervention was performed due to spontaneous drainage, clinical stability, and comorbidities. Outpatient imaging showed complete resolution of the cyst. Discussion: Management of pancreaticoduodenal fistulas hinges on patient stability, fistula output, and evidence of sepsis or peritonitis. Evaluation typically combines cross-sectional imaging (computed tomography, magnetic resonance imaging) with endoscopic assessment (EUS), which clarifies anatomy and guides treatment. In clinically stable patients with controlled drainage and no ongoing infection, conservative therapy, such as antibiotics, nutritional support, and close monitoring, is often sufficient. Endoscopic drainage or stenting is reserved for persistent infection or symptoms, while surgical intervention is considered for uncontrolled sepsis or refractory cases. Spontaneous closure may occur when effective internal drainage is established, as in this case.