Lower gastrointestinal bleed playing hide and seek

A 13-year-old adolescent male presented with an episode of rectal bleed. He has had five such episodes in the past year where he witnessed black tarry stools mixed with fresh blood, painless, not associated with fever or hematemesis. Clinical examination revealed pallor and a soft, non-tender abdomen. Vitals were stable. Blood investigations revealed haemoglobin of 102g/L, WBC count of 10 X 109/L and platelet count of 165 x 109/L. The clotting screen was normal. Upper GI endoscopy and colonoscopy revealed no abnormality. The patient underwent Tc-99m pertechnetate scintigraphy to look for Meckel's Diverticulum in view of painless lower GI bleed.