Two Contrasting Scintigraphy-Negative Pediatric Meckel's Diverticula Identified and Localized by Intestinal Ultrasound and Double-Balloon Enteroscopy: A Report of Two Cases.

Scintigraphy-negative Meckel's diverticulum (MD) is diagnostically challenging in children, particularly when the underlying pathology differs between cases. Technetium-99m pertechnetate scintigraphy is widely used for diagnosis; however, false-negative results may occur when ectopic gastric mucosa is absent or when the diverticulum is inverted. We report two pediatric cases with contrasting scintigraphy-negative MD in which intestinal ultrasound (IUS) suggested target lesions, and double balloon enteroscopy (DBE) enabled direct diagnosis and preoperative localization. Case 1 was a 13-year-old boy with recurrent abdominal pain and hematochezia. IUS revealed localized ileal wall thickening with a hyperechoic polypoid lesion, and transanal DBE identified a pedunculated ulcerated mass approximately 80 cm proximal to the ileocecal valve. Surgical pathology confirmed inverted MD with ectopic gastric mucosa. Case 2 was an 11-year-old girl with recurrent abdominal pain initially treated as ileitis. IUS revealed localized ileal wall thickening with increased vascularity and a blind-ending tubular structure, and DBE showed a double-lumen appearance consisting of the true ileal lumen and a blind-ending diverticular lumen. Pathology confirmed MD without ectopic mucosa. DBE enabled direct diagnosis and preoperative marking without complications in both cases. These cases suggest that IUS may help identify target lesions and that DBE is useful for definitive diagnosis and preoperative localization in children with suspected MD despite negative scintigraphy.