It's important to locate the site of anal bleeding. A complete history and physical examination are an essential part of making a diagnosis. Symptoms such as changes in bowel habits, stool color (to black or red) and consistency, and the presence of pain or tenderness may tell the doctor which area of the GI tract is affected.
Since eating iron-rich foods, bismuth (Pepto Bismol®), or foods such as beets can give the stool the same appearance as bleeding from the digestive tract, a doctor must test the stool for blood before offering a diagnosis. A blood count will indicate whether the person is anemic and also will give an idea of the extent of the bleeding and how chronic it may be.
Endoscopy is a common diagnostic technique that allows direct viewing of the site of anal bleeding. Because the endoscope can detect lesions and confirm the presence or absence of bleeding, doctors often choose this method to diagnose people with acute anal bleeding. In many cases, the doctor can use the endoscope to treat the cause of anal bleeding as well.
The endoscope is a flexible instrument that can be inserted through the mouth or rectum. The instrument allows the doctor to see into the esophagus, stomach, duodenum (esophago-duodenoscopy), colon (colonoscopy), and rectum (sigmoidoscopy). The endoscope also allows the doctor to collect small samples of tissue (biopsies), to take photographs, and to stop the anal bleeding.
Small bowel endoscopy, or enteroscopy, is a procedure that uses a long endoscope. This endoscope may be used to pinpoint unidentified sources of bleeding in the small intestine.
A new diagnostic instrument called a capsule endoscope is swallowed by the person. The capsule contains a tiny camera that transmits images to a video monitor. It is used most often to find bleeding in portions of the small intestine that are hard to reach with a conventional endoscope.