Definition & Overview

Blood in stool can be a disturbing and frightening symptom to experience. Although it can be a sign of a serious problem, it can also have a simple cause. Due to the many possible causes of this symptom, it is important for patients to immediately consult a doctor so that necessary tests can be promptly conducted to come up with an accurate diagnosis.

Cause of Condition

There are many possible causes of blood in stool. Finding some blood in your stool is a sign that there is some bleeding in the digestive tract. Some examples are:

  • Colitis – This condition is also known as the inflammation of the colon, which is linked to an infection or inflammatory bowel disease.

  • Diverticular disease – This is a condition that affects the diverticula, which are small pouches projecting from the wall of the colon. The diverticula can cause blood in stools when they are bleeding or have become infected.

  • Peptic ulcer – A peptic ulcer, often characterized by an open sore in the lining of the stomach or the upper end of the small intestine, can also cause bleeding. A common cause of peptic ulcers is the long-term or excessive use of anti-inflammatory drugs such as ibuprofen and aspirin.

  • Bacterial infection – Bacterial infection can cause a variety of inflammatory conditions inside the digestive tract. The most common bacterium linked to digestive tract infections is helicobacter pylori.

  • Esophageal tears – Tears in the esophagus can cause blood loss that makes its way out through stool.

  • Polyps – Abnormal benign growths in the digestive tract called polyps may bleed and cause blood in stools.

  • Cancer – Malignant tumors in the digestive tract or colon can also cause bleeding. This is harder to diagnose as the blood in stool is usually in very little amounts and is hardly noticeable to the naked eye.

Key Symptoms

In many cases, blood in stool is detected when there is blood in the toilet after a bowel movement or there is blood in the tissue used for wiping after a bowel movement. This blood usually appears as bright red, but it can also appear black and tarry, which is a sign that the bleeding is localized in the higher part of the digestive tract. There are instances, however, where the amount of blood is too small that the symptom is hard to detect or diagnose. To do so, a fecal occult test can be conducted; this test looks for blood that is hidden in the stool.

To help assist in the diagnosis, it is best to observe the type of blood found and to provide the doctor with all the details regarding the bleeding that was experienced. This will help narrow down the possible site of bleeding and can thus bring the number of possible causes down to a more manageable number. The type, color, and amount of blood in stool can provide many clues as to the exact cause of bleeding.

  • Black tarry blood in stool – This is often linked with ulcer or another problem involving the upper digestive tract.

  • Bright red blood – This is caused by bleeding in the lower digestive tract.

  • Maroon-colored blood – This may be caused by diverticulitis.

Sometimes, the blood is also accompanied by other possibly associated symptoms, such as:

When faced with a case of bloody stool, doctors often request certain tests to identify the cause/s of bleeding in the digestive tract. These tests include:

  • Nasogastric lavage – This test is highly effective in determining where the blood originates from. To perform the test, a doctor inserts a tube through the nose and into the stomach to remove the contents of the stomach. The results will show traces of blood if there is bleeding.

  • EGD or esophagogastroduodenoscopy – This is a test where a flexible tube called an endoscope is inserted through the mouth and guided further down until it reaches the stomach and then the duodenum. The endoscope is fitted with a small camera, so that it can take images of the inside of the stomach that are then transmitted to a monitor. This will help the doctor examine the inside of the stomach and duodenum to look for any potential cause of bleeding. This procedure is also performed to obtain a small sample of stomach tissue so it can be examined under a microscope; this procedure is called a biopsy.

  • Enteroscopy – This procedure is performed to assess the condition of the small intestine. It is usually done by having the patient swallow a capsule containing a tiny camera. The camera then produces images that are transferred to a monitor as the capsule makes its way into the digestive tract.

  • Colonoscopy – This is a diagnostic procedure that examines the inside of the colon. Like an EGD, a colonoscopy also makes use of an endoscope, but it is inserted into the rectum to reach the large intestine. A colonoscopy may also be used to take a sample of colon tissue for further examination.

  • Radionuclide scanning – This is a procedure used to observe the blood flow in the digestive tract to detect the potential site of increased bleeding. The procedure involves injecting a small amount of artificially produced radionuclide into a vein and scanning the patient to observe the movement of the said material as it passes through the digestive tract.

  • Barium x-ray – A barium x-ray scan is performed by injecting barium as a contrast material into the patient’s body; an x-ray scanner can then be used to detect and follow the movements of the barium as it passes through the body. The material is usually inserted into the rectum but may also be swallowed.

Who to See & Types of Treatments Available

If a person observes some blood in his stool, it is best to see his family doctor, primary health care provider, general physician, or internal medicine doctor immediately. A general physician should be the primary point of contact since there are many possible causes of the said symptom.

If the bleeding is acute, the foremost goal of treatment is to control the bleeding, which can be done by injecting certain chemicals into the area where the bleeding is coming from. The chemicals are inserted either via endoscopy or angiography.

Once the immediate bleeding has been stopped, the doctor will work towards ensuring that the symptom will not recur. At this point, the doctor will decide the best course of treatment depending on the real cause of bleeding. Common treatments used are:

  • Antibiotics medication
  • Suppression of stomach acid
  • Anti-inflammatory medication
  • Surgery

Bloody stools don’t often require surgery but the latter is necessary if polyps or cancer is causing the symptom.


  • Blanke CD, Faigel DO. Neoplasms of the small and large intestine. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 199.

  • Bresalier RS. Colorectal cancer. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 9th ed. Philadelphia, PA: Elsevier Saunders; 2010:chap 123.

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