TOPIC: Critical Care TYPE: Medical Student/Resident Case Reports INTRODUCTION: Meckel diverticulum(MD), characterized as a common congenital malformation and is well studied in the pediatric population but less so in adults. Our case emphasizes MD as one of the possible diagnoses of gastrointestinal bleeding in adults when CT scans and endoscopic evaluations are unremarkable. Also, if the suspicion is high, the technetium 99m pertechnetate is also not often adequate to exclude the diagnosis. CASE PRESENTATION: 28 year old male with a history of Inflammatory bowel syndrome presented to the emergency department with lightheadedness and palpitations. Soon after, he experienced a large melanotic stool and was transferred to the ICU with hypovolemic shock. His labs were notable for normocytic normochromic anemia for which he was transfused with packed red blood cells. CTA abdomen and pelvis demonstrated no evidence for active extravasation. The patient continued to have massive melenic bowel movements requiring repetitive blood transfusion for his hemorrhagic shock. Bedside double endoscopy showed non-bleeding internal hemorrhoids with no obvious source of bleeding. Subsequently, workup was broadened to a tagged RBC scan which was positive in the mid to distal small bowel prompting small ileal branch embolization. However, bleeding persisted for which Meckel's scan was ordered and found to be suggestive of Meckel's diverticulum. Subsequently, he had a laparoscopic small bowel resection which led to the resolution of symptoms. DISCUSSION: Meckel's Diverticulum is a rare entity in adults with only 17 cases reported in literature in the last year. It usually presents in childhood with more than half of the patients being less than 10 years old.MD usually presents with intestinal obstruction, hemorrhage and inflammation ofthe diverticulum with or without perforation. Bleeding usually occurs from an ulcer due to ectopic gastric mucosa producing acid and damaging the intestinal mucosa. Clinical features are comparable to any other inflammatory condition and can be confused with more prevalent conditions like acute appendicitis. Meckel's nuclear scan proves to be the standard test in case of high suspicion with a sensitivity of 89.6% and specificity of 97.1%. Other testing modalities include X-ray, CT scan or an MRI in case of an obstruction. Mesenteric arteriography in case of GI bleeding, double-balloon enteroscopy or capsule endoscopy can be used in order to directly visualize the MD, or abdominal exploration can be done as required if the diagnosis remains unclear with high index of suspicion.The standard of treatment in case of a symptomatic patient is surgical resection by performing a diverticulectomy that our patient underwent and was discharged to medical floor after stabilization. CONCLUSIONS: Meckel's Diverticulum remains a diagnosis associated with pediatric population although should not be forgotten in cases of adults with unexplained gastrointestinal bleeding. REFERENCE #1: Lequet J, Menahem B, Alves A, Fohlen A, Mulliri A. Meckel's diverticulum in the adult. J Visc Surg. (2017) 154:253–9. 10.1016/j.jviscsurg.2017.06.006 [PubMed] [CrossRef] [Google Scholar] REFERENCE #2: Choi SY, Hong SS, Park HJ, Lee HK, Shin HC, Choi GC. The many faces of Meckel's diverticulum and its complications. J Med Imaging Radiat Oncol. (2017) 61:225–31. 10.1111/1754-9485.12505 [PubMed] [CrossRef] [Google Scholar] REFERENCE #3: Stone PA, Hofeldt MJ, Campbell JE, et al. Meckel diverticulum: ten-year experience in adults. South Med J 2004;97:1038-41. [PubMed] DISCLOSURES: No relevant relationships by Imama Ahmad, source=Web Response No relevant relationships by Anneris Estevez, source=Web Response No relevant relationships by Sneha Lakshman, source=Web Response