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 can range in color from bright red to dark maroon to a dark, tarry color.

Rectal bleeding (blood in stool) facts

  • Rectal bleeding is the passage of blood through the anus.
  • The bleeding may result in bright red blood in the stool, maroon colored or black stool. The bleeding also may be occult (not visible with the human eye).
  • The common causes of rectal bleeding include anal fissure, hemorrhoids, diverticulosis, colon cancer and polyps, colonic polyp removal, angiodysplasias, colitis, proctitis, and Meckel’s diverticula. Rectal bleeding also may be seen with bleeding that is coming from the stomach, duodenum, or small intestine.
  • Rectal bleeding may not be painful; however, other symptoms that may accompany rectal bleeding are diarrhea, and abdominal cramps due to the blood in the stool.
  • Rectal bleeding is commonly evaluated and treated by gastroenterologists and colorectal or general surgeons. The origin of rectal bleeding is determined by history and physical examination, anoscopy, flexible sigmoidoscopy, colonoscopy, radionuclide scans, visceral angiograms, and blood tests.
  • Rectal bleeding is managed by correcting the low blood volume and anemia if present with blood transfusions, determining the site and cause of the bleeding, stopping the bleeding, and preventing rebleeding.
  • Rectal bleeding can be prevented if the cause of the bleeding can be found and definitively treated, for example, by removing the bleeding polyp or tumor. In addition, there it may be appropriate to search for additional abnormalities, for example, polyps or angiodysplasias that have not yet bled but may do so in the future. This may require either gastrointestinal endoscopy or surgery.

Rectal Bleeding Symptoms

These include:

  • Bright red blood coating the stool
  • Dark blood mixed with the stool
  • Black or tarry stool
  • Bright red blood in vomit
  • “Coffee-grounds” appearance of vomit

Other signs, which also need a doctor’s attention, include:

  • Fatigue, weakness, pale appearance
  • Anemia — your blood is low on iron-rich hemoglobin

The location of the bleeding may affect what you notice.

If it comes from the rectum or the lower colon, bright red blood will coat or mix with your stool. The stool may be mixed with darker blood if the bleeding is higher up in the colon or at the far end of the small intestine.

Rectal Bleeding Causes

Some of the most common causes of visible rectal bleeding in adults are outlined below. However, don’t try to diagnose yourself, and always see your GP for a proper diagnosis.

Click on the links for more information about these causes.

  • piles (haemorrhoids) – swollen blood vessels in and around the rectum. They can bleed when you have a bowel movement, which can leave streaks of bright-red blood in your stools and on the toilet paper. Piles may also cause itchiness around your anus. They often heal on their own.
  • anal fissure – a small tear in the skin of the anus, which can be painful as the skin is very sensitive. The blood is usually bright red and the bleeding soon stops. You may feel like you need to keep passing stools, even when your bowel is empty. It often heals on its own within a few weeks.
  • anal fistula – a small channel that develops between the end of the bowel, known as the anal canal or back passage, and the skin near the anus (the opening where waste leaves the body). They’re usually painful and can cause bleeding when you go to the toilet.
  • angiodysplasia – abnormal blood vessels in the gastrointestinal tract, which can cause bleeding. It’s more common in older people and can cause painless rectal bleeding.
  • gastroenteritis – a viral or bacterial infection of the stomach and bowel, which your immune system usually fights off after a few days. It can cause diarrhoea containing traces of blood and mucus, as well as vomiting and stomach cramps.
  • diverticula – small bulges in the lining of your lower bowel. These contain weakened blood vessels that can burst and cause sudden, painless bleeding (you may pass quite a lot of blood in your stools).
  • bowel cancer (colon or rectal cancer) – you should always get checked by your GP if you have rectal bleeding. The only symptom of bowel cancer may be rectal bleeding in the early stages, so don’t ignore it. Bowel cancer can be treated more easily if it’s diagnosed at an early stage.

Less common causes of rectal bleeding

Some of the more unusual causes of rectal bleeding include:

  • anticoagulant drugs – such as warfarin or aspirin, which are taken to reduce your chance of a blood clot but can sometimes cause internal bleeding.
  • inflammatory bowel disease – such as Crohn’s disease or ulcerative colitis. These long-term conditions cause the lining of the bowel to become inflamed. Crohn’s disease affects the gut higher up, whereas ulcerative colitis affects the large bowel and rectum further down. Both tend to cause bloody diarrhoea.
  • bowel polyps – small growths on the inner lining of the colon or rectum. These are common and often don’t cause symptoms, but may lead to a small amount of blood in your stool.
  • sexually transmitted infections (STIs) – any sexual activity involving the anal area can spread STIs, which may sometimes lead to rectal bleeding. Read more about the risks of anal sex.

Diagnosing Rectal Bleeding

  • Examine your anus visually
  • Feel for abnormalities within your rectum with a gloved, lubricated finger
  • Perform a colonoscopy
  • Recommend a flexible sigmoidoscopy
  • Use an anoscope, a short tube with a camera on its tip

How Rectal Bleeding is Treated?

Most cases can be treated. Your plan will depend on what’s causing the bleeding.

You may get an endoscopy. For instance, if your upper digestive tract is bleeding, your doctor may be able to control it by injecting chemicals directly into the problem area, using an endoscope to guide the needle. A doctor can also use heat to treat (or “cauterize”) an area that’s bleeding and surrounding tissue through the endoscope, or place a clip on a bleeding blood vessel.

Those techniques aren’t always enough. Sometimes you need surgery.

Once the bleeding is under control, you may need to take medicine to keep it from coming back.