Mayo Article - Monument Health

Definition

Rectal bleeding can refer to any blood that passes from your anus, although rectal bleeding is usually assumed to refer to bleeding from your lower colon or rectum. Your rectum makes up the lower portion of your large intestine.

Rectal bleeding may show up as blood in your stool, on the toilet paper or in the toilet bowl. Blood that results from rectal bleeding is usually bright red in color, but occasionally can be dark maroon.

Causes

Rectal bleeding may occur for many reasons. Common causes of rectal bleeding include:

Anal fissure (a small tear in the lining of the anal canal)
Constipation
Hard stools
Hemorrhoids (swollen and inflamed veins in your anus or rectum)

Less common causes of rectal bleeding include:

Anal cancer
Angiodysplasia (abnormalities in the blood vessels near the intestines)
Colon cancer
Colon polyps
Crohn's disease a kind of disease that causes the bowels to swell.
Diarrhea
Diverticulosis (a bulging pouch that forms on the wall of the intestine)
Inflammatory bowel disease (IBD)
Ischemic colitis (colon inflammation caused by reduced blood flow)
Proctitis (inflammation of the lining of the rectum)
Pseudomembranous colitis (colon inflammation caused by an infection)
Radiation therapy
Rectal cancer
Solitary rectal ulcer syndrome (ulcer of the rectum)
Ulcerative colitis (a type of inflammatory bowel disease)

When to see a doctor

Call 911 or emergency medical assistance

Seek emergency help if you have significant rectal bleeding and any signs of shock:

Rapid, shallow breathing
Dizziness or lightheadedness after standing up
Blurred vision
Fainting
Confusion
Nausea
Cold, clammy, pale skin
Low urine output

Seek immediate medical attention

Have someone drive you to an emergency room if rectal bleeding is:

Continuous or heavy
Accompanied by severe abdominal pain or cramping

Schedule a doctor's visit

Make an appointment to see your doctor if you have rectal bleeding that lasts more than a day or two, or earlier if the bleeding worries you.