Adult Annular Pancreas Presenting With Gastric Outlet Obstruction Following Semaglutide Initiation: A Case Report.

Annular pancreas is a rare congenital anomaly that may remain clinically silent until adulthood. Its symptoms can be masked or exacerbated by glucagon-like peptide-1 receptor agonists (GLP-1 RAs), which delay gastric emptying. We report a 55-year-old male with type 2 diabetes who developed progressive postprandial vomiting and nine-kg weight loss following semaglutide initiation. Imaging revealed a partial annular pancreas causing second-part duodenal stenosis without malignancy. Symptoms persisted despite semaglutide discontinuation, supporting a fixed mechanical obstruction as the primary aetiology. The patient underwent successful Roux-en-Y gastrojejunostomy and cholecystectomy; histopathology confirmed benign fibrotic pancreatic tissue. At follow-up, the patient was symptom-free with nutritional recovery. This case emphasises that severe gastrointestinal symptoms in patients on GLP-1 RAs should prompt evaluation for structural pathology rather than being attributed solely to medication side effects, ensuring timely surgical intervention.