What test can confirm the presence of a GI bleed during a rectal examination?

The presence of heme positive stool indicates the presence of blood in the gastrointestinal tract, which can suggest a gastrointestinal bleed. This test, also known as a stool guaiac test, is useful during a rectal examination as it detects hemoglobin in the stool, which would not be visible to the naked eye. Therefore, when a stool sample tests positive for heme, it confirms that there is blood present, which directly supports the diagnosis of a GI bleed.

Other diagnostic tests, such as a CT scan or an abdominal ultrasound, may provide imaging of internal structures and help identify sources of bleeding but do not confirm the presence of a bleed during a rectal examination. Blood tests can provide information about hemoglobin levels or blood components, but they do not specifically indicate if there is active bleeding in the gastrointestinal tract. Thus, the heme positive stool test is the most direct and appropriate test for confirming the presence of gastrointestinal bleeding in the context of a rectal examination.