A 29 year old lady complains of an episode of fresh bleed per rectum and abdominal pain. She underwent an upper GI endoscopy and colonoscopy which didn't reveal any pathology except for some blood in the right colon and ileocecal valve. What is the best investigation in this case?

Since both upper GI endoscopy and colonoscopy are not able to identify any lesion, this implies that the bleeding is likely from the small bowel Also, the clinical presentation points towards the diagnosis of Meckel diveiculum. This may contain ectopic gastric mucosa which secrets acid leading to small-bowel ulcerations. 99mTc peechnetate scan is the investigation of choice for Meckel diveiculum.