S4638 When to Heckle the Meckel?: A Case for Re-Evaluating the Reliability of the Meckel’s Scan in Adult Patients

Introduction: Meckel’s diverticulum (MD) is the most common congenital anomaly of the gastrointestinal tract and occurs in approximately 2% of the population. It is defined by the outpouching of all 3 layers of the bowel wall of the ileum, typically within the 2 feet proximal to the ileocecal valve. The diverticulum contains ectopic GI mucosa in about 50% of cases with gastric tissue being the most common type. Various modalities have been employed for diagnosis and there is now increasing evidence to suggest that the traditional Meckel’s scan may no longer be the most reliable approach. Case Description/Methods: A 30-year-old man with a history of multiple prior episodes of unexplained small bowel bleeding presented with hematochezia and acute blood loss anemia. The patient had an initial episode of melena requiring hospitalization in 2016 with no source discovered after push enteroscopy and colonoscopy. He had a Meckel’s scan performed at that time, which showed no scintigraphic evidence for a MD. Upon present-day presentation, he was tachycardic to 120 bpm and hypotensive at 100/70. Hemoglobin was found to be 6.5 gm/dL from baseline 14 gm/dL. Computed tomography angiography abdomen showed no signs of active extravasation, though a hyperdense 3.6 cm polypoid distal ileal filling defect was noted. This was thought by radiology to favor normal distal ileum or blood clot given negative prior Meckel’s scan. Repeat colonoscopy showed red blood in the terminal ileum. Repeat push enteroscopy was without signs of bleeding. Video capsule endoscopy (VCE) revealed erythema in the ileum suspicious for diverticulum versus ulcer. Retrograde single balloon enteroscopy discovered outpouching in the mid-ileum suspicious for MD, which was biopsied and found to have pre-pyloric gastric metaplasia. The patient was referred to surgery for removal of confirmed MD. Discussion: There has been a historical perception that the Meckel’s scan is a highly reliable diagnostic test, likely as a result of its high sensitivity (estimated to be 85-90%) in pediatric populations. Unfortunately, the sensitivity in adults has previously been reported to be much lower at approximately 62%, though more recent data suggests a diagnostic accuracy of only 21% when compared to the gold standard of diagnostic laparoscopy. This case highlights the utility of VCE in combination with balloon-assisted enteroscopy in the diagnosis of MD and also serves as a cautionary tale for providers regarding the false negative rate of the Meckel’s scan in adult patients.