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Rectal bleeding

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 last few inches 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 (tear in the skin of the anus)
  • Chronic constipation
  • Hard stools
  • Hemorrhoids

Less common causes of rectal bleeding:

  • Anal cancer
  • Angiodysplasia (abnormalities in the blood vessels near the intestines)
  • Colon cancer
  • Colon polyps
  • Crohn's disease
  • Diarrhea (causing anal irritation)
  • Diverticulosis (a bulging pouch that forms on the wall of the intestine)
  • Ischemic colitis (colon inflammation caused by reduced blood flow)
  • Proctitis (inflammation of the rectum)
  • Pseudomembranous colitis (colon inflammation caused by an infection)
  • Radiation therapy
  • Rectal cancer
  • Solitary rectal ulcer syndrome (a sore on the wall of the rectum)
  • Ulcerative colitis

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.

Generally, people younger than 40 who whose rectal bleeding is from an obvious cause, such as hemorrhoids, don't need testing. However, many doctors recommend tests such as a colonoscopy for people older than 40 to rule out any possibility of also having cancer that's contributing to the bleeding.

Last updated: June 16th, 2017

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