It can be scary to see blood in your stool or on the toilet paper after you wipe, but most of the time you don’t need to worry. Minor rectal bleeding often resolves naturally or with minimal treatment. Even so, it’s worth your attention, says Mimi Lin, M.D., director of neurogastroenterology and motility education at California Pacific Medical Center in San Francisco. “People shouldn’t ignore rectal bleeding because it may be a sign of something more serious.” If you see red or dark blood after a bowel movement, the first step is to assess the cause and severity, she says.
Rectal Bleeding Causes
It may look alarming, but most rectal bleeding isn’t serious. Here are the most common causes.
- Hemorrhoids: swollen, irritated blood vessels inside the rectum or around the anus. Also called piles, hemorrhoids may bleed when damaged. The most common source of rectal bleeding, hemorrhoids develop from undue pressure on the anal tissues caused by excessive sitting, constipation, pregnancy, obesity or other strain.
- Fissures: small tears or splits in the anal lining, typically caused by constipation and passing hard, dry or large stools.
- Polyps: cellular growths in the intestinal lining. Polyps may bleed even when benign; others may be precancerous and warrant removal. Regular colon screening will alert your doctor to any changes in polyps.
- Proctitis: inflamed rectal tissues, sometimes caused by previous radiation therapy, infections or inflammatory bowel disease.
- Abscesses: infected anal glands; blood vessels may rupture and bleed.
- Diverticulosis: a condition characterized by small, bulging sacs, called diverticula, that form in the intestinal wall; small blood vessels inside these pouches may bleed, causing bloody stools.
- Ulcers: inflamed sores in the stomach, intestinal lining or rectum. When sores bleed, digestive juices break down the blood cells and turn them black; if you see this in your stool, call your doctor.
- Colon or rectal (colorectal) cancer: Rectal bleeding is one symptom of this common cancer. Tell your physician if you experience unexplained blood in your stool or any sudden, persistent changes in bowel function.
Is it Something You Ate?
If your feces look bright red, there could be another, completely harmless cause: red-pigmented foods. Beets, cherries, tomatoes and artificially colored red foods can turn bowel movements (and urine) an unsettling shade of red. Fortunately, this effect resolves naturally within a day or two.
What to Expect at the Doctor
“Your doctor will do a thorough history and physical exam, as well as lab tests,” Dr. Lin says. He or she may also use a short, lighted instrument called an anoscope to look closely at the anal canal and lower rectum.
If warranted, your doctor will suggest a sigmoidoscopy—performed with a short, flexible, camera-equipped tube—to examine the lower colon, or a full colonoscopy, typically performed while you’re sedated, to examine the entire colon.
Your doctor may discuss colon cancer with you, as rectal bleeding can be a symptom. The good news: colon cancer is highly curable when caught early. Whether or not you have rectal bleeding, schedule regular colon screenings if you’re older than 50 or have a family history of cancer or polyps.
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