Mr. J.M. is a 70-year-old man with a 12-year history of type II diabetes. He has a remote history of ischemic heart disease and, in 2005, underwent quadruple aortocoronary bypass following a myocardial infarction. He quit smoking over 10 years ago, and denies history of alcohol abuse. In 2007, laboratory investigations showed a microcytic anemia of 116. His serum ferritin was low at 10 µg/mL (N > 27). Medications at that time included enteric-coated aspirin.

Gastroscopy showed no significant abnormality, with gastric biopsies negative for Helicobacter pylori infection. Duodenal biopsies were negative for celiac disease. At colonoscopy, a small hyperplastic polyp was excised. There was severe diverticular disease of the left hemicolon. He underwent a small bowel barium study that showed no abnormality. He was treated with iron supplements and proton pump inhibitor, bringing normalization of his hemoglobin.

He was seen again in 2008 with a microcytic anemia of 108 and ferritin < 5 µg/mL. Gastroscopy and colonoscopy were repeated with no new abnormality found. He was referred to a hematologist who concluded that his anemia was likely secondary to chronic gastrointestinal bleeding. Hemoglobin electrophoresis was carried out and was negative for thalassemia trait. Fecal occult blood testing was done, which was positive in 3/3 specimens. CT scan of the abdomen and pelvis showed no intra-abdominal mass lesion and small bowel enteroscopy to the level of the proximal jejunum showed no abnormality. He was continued on iron plus proton pump inhibitors.

In early 2009, he presented with a microcytic anemia of 96. Fecal occult blood testing again was positive. A diagnostic test, which had previously been recommended but was not done due to the patient being unable to afford it, was carried out. What do you think it revealed?