RATIONALE: Intramural hematoma of the large intestine is a rare and potentially life-threatening condition. Nonspecific clinical symptoms pose a diagnostic challenge, necessitating prompt recognition for timely and appropriate management. The selection of an optimal therapeutic approach depends on multiple factors, including the etiology and severity of bleeding, the patient's overall condition, and the availability of various treatment modalities.

PATIENT CONCERNS: This case report describes a 67-year-old male admitted for acute abdominal pain and hematochezia persisting for several hours.

DIAGNOSES: Sigmoidoscopy revealed a large, smooth-walled, bluish-purple mass nearly occluding the rectum, suggestive of an intramural hematoma. Multidetector contrast-enhanced computed tomography of the abdomen and pelvis confirmed an extensive intramural hematoma of the rectum and sigmoid colon with active bleeding.

INTERVENTIONS: The patient underwent emergency surgery, during which the massive hematoma was evacuated. Hemostasis was achieved using seton placement and a diverting loop ileostomy. On postoperative day 2, the setons were removed, and reassessment confirmed the absence of active bleeding. The patient's condition gradually improved. Hematological parameters remained stable throughout the follow-up.

OUTCOMES: On the 10th postoperative day, the patient was discharged in good general condition with a well-healing surgical wound. Ileostomy reversal was performed 6 months after the initial hemorrhagic event, and the patient was subsequently discharged in good general condition without any complications and clinical consequences. An unconventional surgical strategy involving hematoma evacuation without intestinal resection preserved physiological bowel function, thereby preventing adverse clinical consequences.

LESSONS: This report highlights a case of extensive, spontaneous intramural hematoma of the rectum and sigmoid colon in a patient receiving anticoagulant therapy. Although rare, these hematomas should be considered in the differential diagnosis of abdominal pain in anticoagulated patients. A timely diagnosis based on clinical evaluation, thorough physical examination, and imaging studies is crucial for appropriate management. In this case, early diagnosis facilitated surgical intervention while preserving intestinal continuity.