Wunderlich syndrome is a rare condition caused by spontaneous bleeding into the kidney without injury. A 61-year-old woman with diabetes mellitus developed an idiopathic left subcapsular kidney hematoma. Contrast-enhanced computed tomography showed hematoma enlargement with perinephric abscess and later gas in the lesion with fistula into the descending colon. Percutaneous drainage confirmed the infection and a tubogram of the fistula. The patient received an ileostomy, antibiotics and drainage. After weeks, the abscess and fistula returned, the catheter was removed, and she was discharged stable after 70 days. This case is the first documented case of colonic fistula in idiopathic Wunderlich syndrome.