Idiopathic Duodenocolic Fistula Presenting as Chronic Diarrhea: Successful Surgical Management After Failed Endoscopic Closure

Idiopathic duodenocolic fistula is an exceptionally rare cause of chronic diarrhea, malabsorption, and weight loss. Management is challenging, especially after failed endoscopic closure. A 47-year-old man with no significant medical history presented with chronic diarrhea, cachexia (BMI 16.7 kg/m²), moderate anemia, and severe hypoalbuminemia. Radiography and MR enterography revealed a fistula between the second and third portions of the duodenum and the hepatic flexure of the colon. Two endoscopic over-the-scope clips (OTSC) closure attempts were unsuccessful. The patient underwent preoperative nutritional optimization, followed by surgical primary closure using a linear stapler. Histopathology confirmed benign chronic inflammation. Postoperatively, the patient achieved full recovery, with resolution of diarrhea and normalization of laboratory parameters at one-year follow-up. Although rare, an idiopathic duodenocolic fistula should be considered in patients with chronic diarrhea and malabsorption. This case underscores that in the absence of common etiologies and after failed endoscopic intervention, timely surgical management represents a highly effective and definitive curative strategy for idiopathic duodenocolic fistula.