Seeing blood in the toilet, on the outside of your stool, or with wiping after a bowel movement is common. Fortunately, most of the causes of such rectal bleeding are not life-threatening; common causes include hemorrhoids and anal fissures. However, the only way to be certain of the cause is to be evaluated by a healthcare provider.
This topic will review when to seek help for blood in the stool, the most common causes of blood in the stool, and tests that may be recommended. (See "Approach to minimal bright red bleeding per rectum in adults".)
WHEN TO SEEK HELP
Most people with minor rectal bleeding do not have colon cancer or another serious condition. However, it is not possible to know the cause of rectal bleeding without an examination. Thus, ANYONE who notices rectal bleeding should talk to their healthcare provider to determine if an examination is needed. (See 'Rectal bleeding tests' below.)
RECTAL BLEEDING CAUSES
Seeing a small amount of blood after wiping, on the outside of your stool, or in the toilet is most commonly caused by hemorrhoids or an anal fissure.
Hemorrhoids — Hemorrhoids are swollen blood vessels in the rectum or anus that can be painful, itchy, and can sometimes bleed (figure 1). Painless rectal bleeding with a bowel movement is a common symptom of hemorrhoids. Bright red blood typically coats the stool or blood may drip into the toilet or stain toilet paper. (See "Patient information: Hemorrhoids (Beyond the Basics)".)
Anal fissure — An anal fissure is a tear in the lining of the anus, the opening where feces are excreted. Anal fissures can cause bleeding and a sensation of tearing, ripping, or burning during or after a bowel movement. (See "Patient information: Anal fissure (Beyond the Basics)".)
Other causes of rectal bleeding — There are many other causes of rectal bleeding, including colon cancer, colon polyps, colitis, and diverticulosis. (See "Etiology of lower gastrointestinal bleeding in adults" and "Approach to acute lower gastrointestinal bleeding in adults".)
In addition, bleeding from higher in the digestive tract, such as the stomach, can produce black, tarry bowel movements because stomach acid turns blood black. Bismuth (such as in Pepto Bismol) and iron supplements can also make the stool appear black. Passing blood from the rectum that is dark red or includes clots usually indicates bleeding from higher in the colon than anal fissures or hemorrhoids would produce.
RECTAL BLEEDING TESTS
The best test for rectal bleeding depends upon your age, symptoms, and past medical history.
Rectal examination — Sometimes a clinician can detect the cause of rectal bleeding with a rectal examination. In younger people, this examination may be all that is necessary.
Anoscopy — Anoscopy allows a clinician to inspect the anus and lower rectum. It can be done in the office and does not require sedation.
Sigmoidoscopy — During a sigmoidoscopy, a clinician can examine the rectum and most of the lower large intestine (figure 2). Sigmoidoscopy can be done without sedation. (See "Patient information: Flexible sigmoidoscopy (Beyond the Basics)".)
Colonoscopy — A colonoscopy is a procedure in which a physician examines the entire colon, usually while the patient is sedated. (See "Patient information: Colonoscopy (Beyond the Basics)".)
WHY SHOULD I WORRY ABOUT RECTAL BLEEDING?
While most rectal bleeding is caused by the non-serious causes mentioned above, bleeding can also be caused by cancerous or precancerous conditions. Precancerous polyps near the end of the colon can mimic bleeding from hemorrhoids. These are generally present in the colon for years before they become cancerous, and they can be removed very safely from the colon, preventing progression to cancer.
Colon cancer may be diagnosed in patients who have ignored bleeding for years because they assumed it was from hemorrhoids. Polyps and colon cancer become more common with aging, and thus investigation of bleeding is most important, and is usually most intensive, in patients over the age of approximately 40 to 50 years. (See "Patient information: Colon and rectal cancer screening (Beyond the Basics)".)
WHERE TO GET MORE INFORMATION
Your healthcare provider is the best source of information for questions and concerns related to your medical problem.
This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.
Patient level information — UpToDate offers two types of patient education materials.
The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.
Patient information: Bloody stools (The Basics)
Patient information: GI bleed (The Basics)
Patient information: Angiodysplasia of the GI tract (The Basics)
Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.
Patient information: Hemorrhoids (Beyond the Basics)
Patient information: Anal fissure (Beyond the Basics)
Patient information: Flexible sigmoidoscopy (Beyond the Basics)
Patient information: Colonoscopy (Beyond the Basics)
Patient information: Colon and rectal cancer screening (Beyond the Basics)
Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.
Approach to minimal bright red bleeding per rectum in adults
Approach to acute lower gastrointestinal bleeding in adults
Hemorrhoids: Clinical manifestations and diagnosis
Clinical features, staging, and treatment of anal cancer
Clinical manifestations and diagnosis of acute diverticulitis in adults
Clinical presentation, diagnosis, and staging of colorectal cancer
Colonic diverticular bleeding
Etiology of lower gastrointestinal bleeding in adults
The following organizations also provide reliable health information:
●National Library of Medicine
●The American Society of Gastrointestinal Endoscopy
●National Digestive Disease Information Clearinghouse