Understanding Rectal Bleeding

What is rectal bleeding?

Rectal bleeding often reveals itself as bright red blood on the toilet paper—usually after a bowel movement—or by turning the toilet bowl water red. Rectal bleeding can also present as extremely dark stool, ranging in color from deep red/maroon to black, and sometimes appearing tar-like (melena).

The color of the blood can indicate where the bleeding is coming from:

  • Bright red blood usually indicates bleeding low in the colon or rectum
  • Dark red or maroon blood usually indicates bleeding higher in the colon or the small bowel
  • Melena usually means bleeding in the stomach, such as bleeding from ulcers

Not all rectal bleeding is visible to the eye. In some cases, rectal bleeding can only be seen by looking at a stool sample through a microscope. There is also a test, called a Hemoccult® test that can be done in a doctor’s office.

What causes rectal bleeding?

Although rectal bleeding is common, only about one-third of those affected seek treatment. Symptoms usually develop quickly, and most causes are treatable and not serious. In some cases, rectal bleeding can be a symptom of a serious disease, such as colorectal cancer. Therefore, all rectal bleeding should be reported to the primary care physician. He or she can do a rectal examination or order tests like a colonoscopy to determine the cause of the bleeding.

Rectal bleeding can be caused by:

What are the symptoms associated with rectal bleeding?

The symptoms of rectal bleeding may include:

  • Rectal pain and/or pressure
  • Bright red blood in/on the stool, on underwear, and/or in the toilet
  • Red, maroon, or black stool color
  • Stool that has a tar-like appearance
  • Confusion
  • Feeling lightheaded or dizzy
  • Fainting

Overview of common causes of rectal bleeding

What are hemorrhoids, the most common cause of rectal bleeding?

Hemorrhoids are swollen veins in the rectum (internal hemorrhoids) or the anus (external hemorrhoids). Hemorrhoids, also called piles, can commonly develop because of chronic constipation or straining at stools, pregnancy, work strain (heavy lifting, etc.), obesity, or anal intercourse.

Hemorrhoid treatment includes addressing the underlying causes, such as treating the constipation or straining habits, or changing work habits if necessary. Sometimes surgical treatment is necessary and may include one of the following methods:

  • Rubber band ligation: a rubber band placed around the base of the hemorrhoid cuts off circulation to the bulk of the hemorrhoid and causes the hemorrhoid to wither away.
  • Sclerotherapy: the injection of a chemical solution around the blood vessel shrinks the hemorrhoid.
  • Laser: a precise laser beam is used to burn away small hemorrhoids.
  • Hemorrhoidal arterial ligation: uses a Doppler probe to locate and tie the blood vessels feeding the hemorrhoid, to shrink it.
  • Procedure for prolapsed hemorrhoids (PPH): puts hemorrhoids that have come out of the anal canal back in their original positions.
  • Hemorrhoidectomy: surgical removal of the hemorrhoid.

What is an anal fissure? 

An anal fissure, a split or tear in the lining of the anus, causes bleeding and burning pain after bowel movements. The usual cause is passing a very hard stool. The pain is caused by a spasm of the sphincter muscle. This happens as a protective measure by the body as stool passes through and expands the tear. Bleeding is result of trauma to the existing tear. Fissures may be mistaken for and misdiagnosed as hemorrhoids.

Fissures often improve by themselves, but if they don't, an ointment or medication applied locally to relax the muscle can relieve the pain. Surgery may be needed for a chronic or recurrent fissure or if excessive sphincter spasms prevent the tear from healing on its own.

What is a perianal abscess?

There are small glands that open inside the anus, believed to help with passing stool. An infection can occur when one of these glands becomes blocked. The pocket of pus that results from the blockage is an abscess. The abscess can be drained under local anesthesia in the doctor's office. Large abscesses need drainage under anesthesia. About a third of all perianal abscesses will develop into an anal fistula.

What is a fistula?

An anal fistula is a consequence of an infection in the perianal area. A fistula is a connection between two spaces. An anal fistula is a connection between the anus or rectum to the skin around the anus. Fistulas usually start as infections in the anal gland that is naturally present in the anus. They require surgery in order to heal. Some anal fistulas have other causes like inflammatory bowel disease, tuberculosis, or radiation. Others can result from surgery in that area.

What are diverticulosis and diverticulitis?

Diverticulosis develops when small pouches (diverticuli) form in weakened sections of intestine lining and protrude through the bowel wall, usually in the sigmoid colon. Diverticuli are a common finding among older people in Western societies and are diagnosed when seen on a colonoscopy or sigmoidoscopy.

Diverticulosis is a benign disorder but bleeding and infection can occur and are associated complications. Diverticuli generally occur without symptoms, unless they become blocked and infected, causing diverticulitis. Symptoms of diverticulitis include abdominal pain, fever, and a sudden change in bowel habits. Treatment may include a special diet, antibiotics, or surgery.

What is inflammatory bowel disease (IBD)?

Inflammatory bowel disease (IBD) is an inflammation of the small or large intestine. There are two types of IBD. One type of IBD is Crohn's disease, marked by patches of inflammation occurring anywhere in the digestive tract. The other type of IBD, colitis, is marked by inflammation in the large bowel.

There are several other types of colitis, including:

  • Infectious colitis (caused by an infection that attacks the large bowel)
  • Ischemic colitis (the result of a poor blood supply to the colon)
  • Radiation colitis (following radiotherapy, usually for prostate, rectal, or gynecological cancer)
  • Ulcerative colitis (ulcers/sores in the large intestine lining)

IBD symptoms may include:

  • Fever
  • Rectal bleeding
  • Diarrhea
  • Abdominal pain and/or cramping
  • Intestinal blockage

Treatment of inflammatory bowel disease is critical and may involve a special diet, medication to eliminate or reduce inflammation, and/or surgery.

What are ulcers?

Ulcers are sores in the stomach lining or in the first section of the small intestine (the duodenum,) caused by an imbalance of digestive fluids in the stomach and the duodenum. While abdominal pain is the most common symptom of ulcers, many ulcers produce no obvious symptoms.

Ulcers that bleed into the gastrointestinal tract may cause black stool, sometimes with a tar-like appearance. Ulcers are usually successfully treated without surgery, and successful treatment may also prevent new ulcers from forming. Treatment methods may include:

  • Special diet
  • Antibiotics
  • Medications that neutralize gastric acid, or reduce the secretion of gastric acid
  • Medications that strengthen gastric acid resistance in the stomach and the duodenum

What are polyps, and how are polyps related to colorectal cancer?

Since rectal bleeding can sometimes be a symptom of colorectal cancer – cancer of the colon or rectum – this is the primary reason rectal bleeding should not be ignored. Colorectal cancer is a common form of cancer that can usually be cured if diagnosed and treated early enough.

Colorectal cancer occurs when the normal growth and division of the cells lining the large bowel goes out of control, initially resulting in the formation of a polyp(s). A polyp can appear similar to a small mushroom that is attached to the lining of the large bowel. Polyps that become large can bleed.

While there are many types of polyps that are not cancerous, certain polyps are considered precancerous and can develop into cancer if left untreated. Therefore, removing polyps before they develop such severe changes can prevent cancer. Colonoscopy is the procedure used by physicians to locate and remove polyps to prevent colorectal cancer.

People having an increased risk of colorectal cancer include those who have a family history of colorectal cancer, and people who have previously had cancer or polyps.

When colorectal cancer occurs, treatment may include:

The early stages of colorectal cancer may have no apparent symptoms. Thus, regular screening is important, particularly for individuals who are at increased risk.


Explore Related Content

© Copyright 1995-2017 The Cleveland Clinic Foundation. All rights reserved.

This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 1/27/2015…#14612