Stool Color Changes (cont.)
Benjamin Wedro, MD, FACEP, FAAEM
Benjamin Wedro, MD, FACEP, FAAEM
Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.
Bhupinder Anand, MD
In this Article
Black tarry stools
Black stools are a worrisome symptom because it may be due to a large amount of bleeding into the GI tract, most often from the upper GI tract including the esophagus, stomach, and duodenum. Red blood cells are broken down by digestive enzymes in the intestine and turn the stool black. These stools tend to be tarry (sticky), and foul smelling. This can be a medical emergency; black tarry stools should not be ignored.
Blood from nosebleeds or from dental procedures and injuries can be swallowed and may be the cause of black stool, but the amount of bleeding usually is not substantial enough to do this.
Bright red stools
The most common cause of bright red stool is bleeding from hemorrhoids, but other bleeding causes are much more significant. For that reason, blood in the stool should never be ignored. Other causes include infections of the intestines, inflammatory bowel disease (Crohn's disease, ulcerative colitis), diverticular bleeding, tumors, and arteriovenous malformations (abnormal communications between arteries and veins in the wall of the intestine that rupture). Brisk bleeding from the upper GI tract may cause stools to be red instead of black if there has not been enough time for the red blood cells to be digested. Red food coloring and beets can also give a reddish hue to the stool.
Light-colored white or clay-colored stools
White-or clay colored stool are often seen with diseases of the liver or bile ducts. It also may be caused by pancreatic cancer that blocks the bile ducts. Lack of bile gives stool its brown color and leaves it appearing pale.
Medically Reviewed by a Doctor on 9/16/2015
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