Massive lower gastrointestinal bleeding in a young adult due to Meckel's diverticulum without ectopic gastric mucosa.

Meckel's diverticulum is the most common congenital anomaly of the gastrointestinal tract, occurring in approximately 2% of the general population. However, symptomatic cases in adults are uncommon, and bleeding is usually caused by ulceration resulting from the ectopic gastric mucosa. Here, we report a case of massive lower gastrointestinal bleeding in a 22-year-old woman with Meckel's diverticulum without ectopic gastric mucosa. The patient presented with hematochezia and significant anemia. Initial endoscopic evaluation and contrast-enhanced computed tomography failed to identify the bleeding source. Transanal double-balloon enteroscopy revealed a tubular structure 35 cm proximal to the ileocecal valve, with a circumferential ulcer at its opening. Although active bleeding was not observed, contact with the endoscope induced oozing. Laparoscopic segmental resection was performed, and histopathology confirmed the presence of a true diverticulum without ectopic tissue. The patient's postoperative course was uneventful, with no recurrence of bleeding observed during the 3-month follow-up period. This case highlights that a Meckel's diverticulum can cause clinically significant bleeding, even in the absence of ectopic mucosa, and emphasizes the diagnostic value of enteroscopy.