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Gastrointestinal Bleeding (cont.)

What are causes and risk factors for lower gastrointestinal (GI) bleeding?

  • Diverticulosis: One of the most common causes of lower GI bleeding. Small out-pockets, or diverticula, form in the wall of the colon (large intestine), usually in a weakened area of the bowel wall. The person may develop several pockets, which are more common in people who have constipation and strain during a bowel movement.
  • Cancers: One of the early signs of colon or rectal cancers may be blood in the stool.
  • Inflammatory bowel disease (IBD): Flares of inflammation from IBD (Crohn's disease and ulcerative colitis) often cause mucousy stool that has blood mixed in it.
  • Infectious diarrhea: Some viruses or bacteria can cause damage to the inner lining of the intestines, which can lead to bleeding.
  • Angiodysplasia: Along with diverticulosis, this is one of the most common causes of lower GI bleeding. Angiodysplasia is a malformation of the blood vessels in the wall of the GI tract. These are most commonly in the large intestine and often bleed. The elderly and people with chronic kidney failure develop the disease most often.
  • Polyps: Intestinal polyps are noncancerous tumors of the GI tract, occurring mostly in people older than 40 years of age. A small proportion of these polyps may transform into cancer. Colon polyps may bleed rapidly, or they may bleed slowly and go undetected.
  • Hemorrhoids and fissures: Hemorrhoids are swollen veins in and around the anus. Repeated stretching from straining during bowel movements causes them to bleed. Bleeding from hemorrhoids is usually mild, intermittent, and bright red. Anal fissures, or tears in the anal wall, also may trigger small amounts of bright red bleeding from the anus. Forceful straining during passage of hard stool usually causes such tears, which can be very painful and may require surgery.

How is the cause of upper or lower gastrointestinal (GI) bleeding diagnosed?

  • A doctor will perform a complete history and physical exam to evaluate the patient's problem. The doctor may include a digital rectal exam, to test for visible or microscopic blood from the rectum.
  • Lab tests such as complete blood count (CBC), serum chemistries, liver tests, and coagulation studies also can be helpful to determine the rate or severity of bleeding and to determine factors that may contribute to the problem.
  • The doctor may need to perform a procedure called an endoscopy or a colonoscopy. An endoscope is a long tube with a tiny camera at the end. It is passed into the stomach, and the first part of the small intestine. A colonoscopy refers to the passage of a tube with a tiny camera through the rectum into the colon, to directly see the source of bleeding. Both procedures can be diagnostic, finding the source of bleeding; and therapeutic, stopping it.
Medically Reviewed by a Doctor on 10/17/2016
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