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Blood in Stools

Causes of Bloody Stools and Rectal Bleeding


Updated May 16, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Blood in Stools
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Like finding a lump in the breast, seeing blood in your stool can send you into a tailspin of panic. For most people, the fear is that this is a sign of colon cancer. Although blood in the stool is considered a red-flag digestive symptom, it doesn't automatically signify a life-threatening illness.

If you find any blood in your stool or see any evidence of rectal bleeding, the first thing you should do is to call your doctor and set up an appointment. While you are waiting you can educate yourself as to what may be wrong, since information is a great antidote to anxiety. To help you to have some knowledge regarding possible causes of blood in your stool, I turned to UpToDate, a trusted online reference used by doctors and patients. Here is what the experts there had to say about possible causes of bloody stools:

"Seeing a small amount of blood after wiping, on the outside of your stool, or in the toilet is most commonly caused by hemorrhoids or an anal fissure.
  • "Hemorrhoids - Hemorrhoids are swollen blood vessels in the rectum or anus that can be painful, itchy, and can sometimes bleed. Painless rectal bleeding with a bowel movement is a common symptom of hemorrhoids. Bright red blood typically coats the stool or blood may drip into the toilet or stain toilet paper.
  • "Anal fissure - An anal fissure is a tear in the lining of the anus, the opening where feces are excreted. Anal fissures can cause bleeding and a sensation of tearing, ripping, or burning during or after a bowel movement.
  • "Other causes of rectal bleeding - There are many other causes of rectal bleeding, including colon cancer, colon polyps, colitis, and diverticulosis.
"In addition, bleeding from higher in the digestive tract, such as the stomach, can produce black, tarry bowel movements because stomach acid turns blood black. Bismuth (such as in Pepto Bismol) and iron supplements can also make the stool appear black. Passing blood from the rectum that is dark red or includes clots usually indicates bleeding from higher in the colon than anal fissures or hemorrhoids would produce."

You can see that although color offers a big clue as to what might be wrong, it does not necessarily give the whole picture as there are things not related to illness that can affect the color of stool. This information from UpToDate also illustrates how the possible explanations for rectal bleeding range from the relatively benign condition of hemorrhoids to some of the more serious digestive diseases. Further assessment is essential in order to figure out precisely what is going on in your digestive system.

Based on your symptom picture, your doctor will choose which diagnostic tests are most appropriate. Most doctors will take a thorough history and do a physical examination, which may include a rectal exam. Blood work may or may not be taken. Some other possibilities include:

Blood in your stool is a symptom that cannot be ignored. If you see any sign of rectal bleeding, it is imperative that you bring it to the attention of your doctor. With a proper diagnosis, the underlying problem can be appropriately addressed.

Want to learn more? See UpToDate's topic, "Patient information: Blood in the stool (rectal bleeding) in adults" for additional in-depth, current and unbiased medical information, including expert physician recommendations.


Penner, Robert M. and Majumdar, Sumit R. "Patient information: Blood in the stool (rectal bleeding) in adults" UpToDate. Accessed: August 2009.

DISCLAIMER: The information contained in this site is for educational purposes only, and should not be used as a substitute for personal care by a licensed physician. Please see your physician for diagnosis and treatment of any concerning symptoms or medical condition.

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