Is bright red blood in the stool serious?

Bright red blood in your stool needs to be evaluated by your doctor.
Bright red blood in your stool needs to be evaluated by your doctor.

The presence of blood in the stool needs to be evaluated by your doctor.

In most cases, the bright red blood in stools is not an immediate threat to life. The most common causes are piles, anal polyps, anal fissures and colitis (inflammation of the large bowel). These conditions may cause recurrent episodes of blood loss and affect quality of life, but they are not fatal. Rarely, cancers arising from the rectum and anus can cause bright red blood in stools. Such cancers can also occur in people with a history of piles and colitis. Hence, it is important to pay attention to this symptom and contact your healthcare professional immediately.

What causes blood in stools?

Blood in stools is a symptom of injury to the gut (digestive tract). When fresh blood is seen in the stool, it is called hematochezia. It is a marker of rectal and anal disease. Dark tarry  stool is called melena. It points to bleeding from the small intestine or stomach.

The following conditions may cause blood in stools

  • Hemorrhoids: The painless, bright red blood that coats the stool or toilet paper may be due to hemorrhoids (piles). Piles are swollen veins present in the lower part of the rectum.
  • Anal fissure: The bright red blood that covers the stools on one side and is accompanied by intense pain may be due to anal fissure. This is a small tear at the margin of the anus from where the stools are expelled.
  • Colitis (infections): The infection of the large intestine by amoebas or bacteria (such as E. coli and Shigella) can also cause blood in stools. This is accompanied by diarrheas, fever and abdominal cramps.
  • Ulcerative colitis (inflammatory bowel syndrome): This disease is due to the malfunctioning of the immune system. It causes ulcers in the colon. Other symptoms are diarrhea that lasts more than a week, stomach cramps, joint pain and weight loss. It has active episodes (periods of flares) and remissions (the phase when symptoms go away).
  • Colon cancers: A cancerous growth in the rectum or anus may cause red blood in the stools. Other symptoms may include weight loss, loss of appetite and alternating diarrhea and constipation.
  • Polyps: These are noncancerous masses found in the anus and rectum as you age. These may cause bleeding if they get twisted resulting in blood in stools.
  • Diverticulitis: Diverticula are small pouches that form in the gut, typically the large bowel, of some people. When these diverticula get infected and swollen (diverticulitis), they may cause dark red blood in the stools.
  • Angiodysplasia: Some people may have an abnormal blood vessel malformation in the small intestine. If it bursts due to pressure or trauma, there may be dark red blood in the stools.
  • Ulcers: Ulcers in the upper gut, stomach  or esophagus may also cause blood in stool, but such blood is blackish and causes tar-colored stools.


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How will my doctor diagnose the cause of blood in my stool?

The physician will conduct certain tests to find the site and cause of bleeding. The following tests are commonly done to assess blood in stool

  • Anoscopy: Done in clinic settings, it does not require anesthesia. An instrument is inserted inside the anus, and the doctor can check for piles, fistulas or polyps in the anus.
  • Sigmoidoscopy: Done in clinic settings, it does not require anesthesia. A sigmoidoscope (an instrument) is inserted inside the anus. The lower gut and anus can be examined with this test.
  • Colonoscopy: This study requires sedation. A colonoscope (pipe-like instrument with a camera and light source) is inserted through the anus and advanced upwards. The camera projects the image on a screen where the doctor can check inside the colon for any tumors or ulcers. Enteroscopy is a similar procedure that is done to visualize the inside of the small intestine.
  • Esophagogastroduodenoscopy (EGD): This study requires sedation. A pipe-like instrument with a front camera is inserted through the mouth. As it moves through the esophagus and into the stomach and  into the small intestine, the camera projects images onto the screen where the doctor can see the insides of the upper gut and stomach to check for any tumors or ulcers.
  • Barium studies: A series of X-rays are taken after drinking a solution of barium salt. This highlights any masses or ulcers or narrowing in the digestive tract.
  • Laparotomy: If the above measures fail, open laparotomy is performed where the abdomen is opened surgically to find the cause of the bleeding.
  • Angiography: This procedure is performed to find bleeding from an artery or any abnormal blood vessel (angiodysplasia). A dye is injected and its pathway is examined on computed tomography (CT) scans or magnetic resonance imaging (MRI) scans.

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