Gastroenterology and Hepatologycommon
A 69-year-old man has had three episodes of melaena over two months and requires repeated iron infusions. He takes no non-steroidal anti-inflammatory drugs and has no abdominal pain or weight loss. Gastroscopy and colonoscopy, including examination of the terminal ileum, have been normal on two occasions; coeliac serology is negative. His haemoglobin is 89 g/L (130–170 g/L), with ferritin 8 microg/L (30–300 microg/L). Which one of the following is the most appropriate next investigation?