Rare case of spontaneous duodeno-colic fistula.

A 48-year-old woman presented to the outpatient clinic with a 4-month history of alternating diarrhea and constipation with bloating. Physical examination revealed a body mass index of 22.89 kg/m², normal development, and no tenderness or rebound tenderness in the abdomen. The patient has maintained a stable body size since birth, with a previously healthy status and no history of abdominal surgery or trauma. Endoscopic examination revealed an abnormal channel between the posterior wall of the duodenal bulb to the hepatic flexure of the colon. The patient was managed with conservative treatment, including acid suppression and modulation of the gut microbiota, and was closely monitored. Surgical intervention would only be considered in the event of severe symptoms or complications. Over a five-month follow-up period, the patient's symptoms improved.