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.