Unmasking a Meckelʼs Diverticulum: Using Capsule Endoscopy and Ranitidine!

Abstract

Introduction: Meckel's Diverticulum, a remnant of the omphalomesenteric duct, is a congenital malformation of the GI tract with ectopic tissue. Diverticulum containing gastric mucosa have increased rates of bleeding. A Meckel's Scan is often used for diagnosis but, as this case shows, is not always reliable.Figure: Capsule endoscopy.Figure: Meckel's Scan.Figure: Intraoperative picture.Case Description: A healthy 20-year-old male presents with hematochezia. He denied symptoms of abdominal pain, or systemic signs such as iritis, oral ulcers, perianal fistula or joint pains. There was no infectious exposure or recent antibiotic use. He was hemodynamically stable with a hemoglobin drop to 7.0 gm/dL from a normal baseline. Workup involved upper and lower endoscopy without a bleeding source identified. Bleeding ultimately self-resolved and hemoglobin stabilized prior to discharge. The patient underwent Meckel's scan, and CT angiography without identifiable source. One year later he represented to the hospital with worsening hematochezia. He was in hemorrhagic shock requiring ICU admission and multiple transfusions. Repeat upper and lower endoscopy were again negative, as was MRI enterogram. Capsule endoscopy was suspicious for a diverticulum in distal small bowel. Meckel's scan, was repeated with pre-procedural administration of ranitidine for 3 days. Scan revealed increased metabolic activity in the right lower quadrant, consistent with Meckel's diverticulum. The patient underwent small bowel resection of the involved segment without return of symptoms at follow up. Discussion: The incidence of gastric mucosa in Meckel's diverticulum is estimated to be between 30-60%, but prevalence is almost 100% when bleeding is present due to ulceration risk. 99m technetium pertechnetate, used in a Meckel's scan, is an isotope taken up by gastric mucosa aiding identification of ectopic sites. Sensitivity of a Meckel's scan ranges from 60-97% with a specificity of 95%. Ranitidine increases nuclear tracer retention and reduces washout via slowing of its release from gastric mucosal cells, increasing test sensitivity. Pre-administration of ranitidine should be used as an adjunct maneuver for identification of Meckel's diverticulum if clinical suspicion is high. In our patient capsule endoscopy findings prompted us to revisit the diagnosis and repeat the scan with ranitidine confirming the diagnosis.