Rationale: Bleeding in the gastrointestinal tract is a common complication of oral anticoagulant therapy (AT), and it usually appears as mucosal erosion or ulcer; however, intestinal submucosal hematoma (ISH) is an uncommon cause of hemorrhage.
Patient concerns: This report presents the case of a 70-year-old woman with acute hematochezia induced by AT. She underwent computed tomography and endoscopy.
Diagnoses: Colon submucosal hematoma.
Interventions: Conservative treatment had no effect, and the patient underwent emergency surgery.
Outcomes: Surgical resection showed hemorrhage and necrosis in the left colon, and the patient recovered 24 hours after surgery and continued AT.
Lessons: The present case indicates that the ISH should be kept in mind as a complication of AT. It can be managed conservatively in some stable patients, but emergency surgery may be needed in some serious situations.