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Advice About Bright Red Blood in Stool

The Potential Causes of This Disturbing Symptom

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Updated May 16, 2014

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

Advice About Bright Red Blood in Stool
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Blood is supposed to stay in your body. Seeing blood in your bowel movement is very frightening. It is also an indication that something is not working right. But it is not always a herald of colon cancer.

Rectal bleeding has many causes, but only one of them is colon cancer. The best action you can take now, to advocate for yourself, is to pay attention to this symptom and be prepared to discuss it with your doctor. Ask yourself these questions:

  • Was the blood in the stool, toilet bowl or on the toilet paper?

  • Was the blood bright red or dark red?

  • Approximately how much blood did you see? (Keep in mind, a drop of blood in a toilet bowl will turn all of the water red.)

  • Did you have to strain to pass the bowel movement?

  • How frequently do you have bowel movements?

  • Do you have other symptoms?

  • When was your last colon screening exam or colonoscopy?

  • Do you have a history of polyps or a family history of polyps?

What Causes the Bleeding?

Many things can cause blood in the stool, ranging from abrasive toilet paper to a large, bleeding polyp. Like the lining of your mouth or nose, the lining of the colon is very vascular and has a healthy blood supply. A smear of blood on the toilet paper may be nothing to worry about, but don’t take a chance. Talk to your doctor. He or she will help you discover the cause.

Hemorrhoids are a common, mostly benign problem. They are the No. 1 cause of bright red blood smears on the toilet paper. You may or may not feel any associated discomfort with a hemorrhoid. Pregnancy and straining on the toilet are two common causes of these swollen blood vessels, which are easily treatable and may even resolve on their own.

Inflammatory processes in the colon, such as irritable bowel disease (IBD), irritable bowel syndrome (IBS), Crohn’s disease, ulcerative colitis or diverticular disease, can cause bright red or dark red blood in the stools.

Colon polyps can and do bleed at times, especially following a colonoscopy or biopsy. Most polyps are benign growths that do not stimulate any symptoms (hence the importance of routine colon screening). However, sometimes the larger ones can bleed, which may require a colonoscopy for investigation and removal of the polyp. Untreated polyps can lead to colon cancer.

Constipation and straining to pass a large bowel movement can lead to smears of bright red blood on the toilet paper. Not drinking enough water, low-fiber diets and a lack of exercise can lead to constipation. Let your doctor know if you are straining to pass bowel movements. This straining can lead to tiny, uncomfortable tears in your anal tissues, called fissures. Anal intercourse can also cause these tiny fissures and rectal bleeding.

Untreated bowel infections, such as Escherichia coli (E. coli), can cause bloody diarrhea and abdominal discomfort. E. coli can stem from eating undercooked meats or unpasteurized juice or dairy products. The infection requires antibiotic therapy.

Colon cancer can cause blood in the stool. Caught early, most cancers of the colon do not generate any symptoms. This is why fecal testing is suggested yearly, to catch cancer very early. If a tumor is bleeding to the point where you see the blood in your stool, the cancer may be at an advanced stage. If the visible blood in your stool is from colon cancer, it is most likely from the left side of the colon (descending colon, sigmoid colon or rectum). Any blood from the right colon will merge with the stool and is probably undetectable to the human eye.

During Your Doctor’s Visit

Your doctor will complete a physical exam to look for any overt causes of the rectal bleeding (hemorrhoids, anal abrasion) and obtain a medical history. He or she may order tests to further investigate the cause, even if it is obvious. The doctor might order a:

  • Complete blood count: Determines how much blood you may have lost.

  • Clotting time: If you take anticoagulants (blood thinners), the doctor may want to check if your blood is too thin (runny)

  • Fecal occult blood test (FOBT) or fecal immunochemical test (FIT): Checks for the presence of blood in the stool.

  • Colonoscopy: Uses a scope to take a look inside the colon. This test allows the doctor to see, and possibly remove, bleeding polyps from the lining of the colon.

  • Sigmoidoscopy – Similar to a colonoscopy, but allows the doctor to see only the final portion of the colon, including the sigmoid colon and the rectum.

  • X-rays: Films of the lower intestinal tract may show any large deformities of the colon.

Following the test(s), your doctor will discuss the findings with you, potentially order further testing if abnormalities are found or develop a treatment plan, as needed.

When to Call the Doctor Now

If the bleeding does not stop, you notice large amounts of blood or have foul-smelling stools with a coffee-grain appearance, you need to seek treatment right away. Your doctor will have to find – and stop – the cause of the bleeding.

Sources:

American Cancer Society. (2006). The Complete Guide to Colorectal Cancer. Atlanta: American Cancer Society Health Promotions.

American Society for Gastrointestinal Endoscopy. (n.d.). Understanding Minor Rectal Bleeding.Accessed December 11, 2011.

Illinois Department of Public Health. (n.d.). Escherichia coli 0157:H7. Health Beat. Accessed December 13, 2011.

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