Blood in Stool

Blood in the stool can be frightening, whether you discover it while wiping after a bowel movement or from a test ordered by your health care provider. While blood in stool can signal a serious problem, it doesn't always. Here's what you need to know about the possible causes of bloody stools and what you -- and your doctor -- should do if you discover a problem.

Causes of Blood in Stool

Blood in the stool means there is bleeding somewhere in your digestive tract. Sometimes the amount of blood is so small that it can only be detected by a fecal occult test (which checks for hidden blood in the stool). At other times it may visible on toilet tissue or in the toilet after a bowel movement as bright red blood. Bleeding that happens higher up in the digestive tract may make stool appear black and tarry.

Possible causes of blood in stool include:

Diverticular disease. Diverticula are small pouches that project from the colon wall. Usually diverticula don't cause problems, but sometimes they can bleed or become infected.

Anal fissure . A small cut or tear in the tissue lining the anus similar to the cracks that occur in chapped lips or a paper cut. Fissures are often caused by passing a large, hard stool and can be painful.

Colitis . Inflammation of the colon. Among the more common causes are infections or inflammatory bowel disease.

Angiodysplasia. A condition in which fragile, abnormal blood vessels lead to bleeding.

Peptic ulcers. An open sore in the lining of the stomach or duodenum, the upper end of the small intestine. Many peptic ulcers are caused by infection with a bacterium called Helicobacter pylori (H. pylori). Long-term use or high doses of anti-inflammatory drugs such as aspirin, ibuprofen, and naproxen can also cause ulcers.

Polyps or cancer . Polyps are benign growths that can grow, bleed, and become cancerous. Colorectal cancer is the fourth most common cancer in the U.S. It often causes bleeding that is not noticeable with the naked eye.

Esophageal problems. Varicose veins of the esophagus or tears in the esophagus can lead to severe blood loss.


Blood in Stool Diagnosis

It is important to have a doctor evaluate any bleeding in the stool. Any details you can give about the bleeding will help your doctor locate the site of bleeding. For example, a black, tarry stool is likely an ulcer or other problem in the upper part of the digestive tract. Bright red blood or maroon-colored stools usually indicate a problem in the lower part of the digestive tract such as hemorrhoids or diverticulitis.

After getting a medical history and doing a physical exam, the health care provider may order tests to determine the cause of bleeding. Tests may include:

Nasogastric lavage. A test that may tell your doctor whether bleeding is in the upper or lower digestive tract. The procedure involves removing the contents of the stomach through a tube inserted into the stomach through the nose. If the stomach does not contain evidence of blood, the bleeding may have stopped or is more likely in the lower digestive tract.

Esophagogastroduodenoscopy (EGD). A procedure that involves inserting an endoscope, or flexible tube with a small camera on the end, through the mouth and down the esophagus to the stomach and duodenum. The doctor can use this to look for the source of bleeding. Endoscopy can also be used to collect small tissue samples for examination under a microscope (biopsy).

Colonoscopy . A procedure similar to an EGD except that the scope is inserted through the rectum to view the colon. As with an EGD, colonoscopy can be used to collect tissue samples to biopsy.

Enteroscopy. A procedure similar to EGD and colonoscopy used to examine the small intestine. In some cases this involves swallowing a capsule with a tiny camera inside that transmits images to video monitor as it passes through the digestive tract.

Barium X-ray. A procedure that uses a contrast material called barium to make the digestive tract show up on an X-ray. The barium may either be swallowed or inserted into the rectum.

Radionuclide scanning. A procedure that involves injecting small amounts of radioactive material into a vein and then using a special camera to see images of blood flow in the digestive tract to detect where bleeding is happening.


Angiography. A procedure that involves injecting a special dye into a vein that makes blood vessels visible on an X-ray or computerized tomography (CT) scan. The procedure detects bleeding as dye leaks out of blood vessels at the bleeding site.

Laparotomy. A surgical procedure in which the doctor opens and examines the abdomen. This may be necessary if other tests fail to find the cause of bleeding.

Health care providers also order lab tests when there is blood in stools. These tests may look for clotting problems, anemia, and the presence of H. pylori infection.

Associated Symptoms

A person with blood in the stool may be unaware of bleeding and might have reported no symptoms. On the other hand, they may also have abdominal pain, vomiting, weakness, difficulty breathing, diarrhea, palpitations, fainting, and weight loss depending on the cause, location, length, and severity of the bleeding.

Blood in Stool Treatments

A doctor may use one of several techniques to stop acute bleeding. Often endoscopy is used to inject chemicals into the site of bleeding, treat the bleeding site with an electric current or laser, or apply a band or clip to close the bleeding vessel. If endoscopy does not control bleeding, the doctor may use angiography to inject medicine into the blood vessels to control bleeding.

Beyond stopping the immediate bleeding, if necessary, treatment involves addressing the cause of bleeding to keep it from returning. Treatment varies depending on the cause and may include medications such as antibiotics to treat H. pylori, ones to suppress acid in the stomach, or anti-inflammatory drugs to treat colitis. Surgery may be needed to remove polyps or the parts of the colon damaged by cancer, diverticulitis, or inflammatory bowel disease.

Depending on the cause, however, treatment may involve simple things you can do on your own. These including eating a high-fiber diet to relieve constipation that can cause and aggravate hemorrhoids and anal fissures, and sitting in warm or hot baths to relieve fissures.

Your doctor will prescribe or recommend treatment based on the diagnosis.

WebMD Medical Reference Reviewed by Melinda Ratini, DO, MS on April 13, 2015



MedlinePlus: "Bloody or tarry stools."

Nebraska Colon Cancer Screening Program: "Rectal Bleeding: What You Should Know."

MedlinePlus: "Gastrointestinal fistula."

NYU Langone Medical Center: "Angiodysplasia of the Colon."

National Digestive Diseases Information Clearinghouse: "Bleeding in the Digestive Tract."

The Ohio State University Medical Center: "Peptic Ulcers."

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