A Case of Severe Acute Pancreatitis Following Endoscopic Biopsy of the Ampulla of Vater: A Rare Adverse Event of Esophagogastroduodenoscopy.

Histological biopsy is essential for diagnosing ampullary tumors; however, it can occasionally result in severe adverse events. A 49-year-old male underwent esophagogastroduodenoscopic screening, which revealed an ampulla of Vater with enlargement of the oral protrusion. An endoscopic biopsy was performed; several hours later, the patient developed severe acute pancreatitis requiring hospitalization. The biopsy result was benign, and no gallstones, ductal abnormalities, or other etiologies were identified on endoscopic ultrasonography or magnetic resonance cholangiopancreatography, and the biopsy was considered the most likely trigger. The patient recovered with conservative management and was discharged on day 14. No recurrence has been observed 3 months after discharge. Although acute pancreatitis following biopsy of the ampulla of Vater is extremely rare, it can be fatal. Endoscopists should be aware of this potential risk, carefully assess the necessity of biopsy, and ensure that patients provide informed consent before the procedure.