Formation of gastrocolic fistula during treatment for peptic ulcer.

We report a case of gastrocolic fistula (GCF) caused by a gastric ulcer and rare endoscopic findings indicating the early stages of GCF formation. The patient was a 58-year-old man who was hospitalized with upper abdominal pain. He was diagnosed as having a gastric ulcer, and was prescribed a proton pump inhibitor (PPI), but did not comply with the medication. One year later, he was again referred with recurrent abdominal pain. Endoscopic examination showed what appeared to be a portion of exposed colonic wall located in the center of an active gastric ulcer, and repeated endoscopy after PPI treatment for 8 days demonstrated a typical GCF. A preoperative diagnosis of GCF was made, and the patient underwent wide gastrectomy with partial resection of the transverse colon.