Rectal bleeding

About rectal bleeding 

In general, bright-red blood means the bleeding has come from somewhere near your anus.

This is a typical sign of piles (haemorrhoids) or a small tear (anal fissure) in the skin of your anus.

Although these are common problems, don't let embarrassment stop you seeing your GP.

You should always get rectal bleeding checked to rule out more serious causes.

If the blood is dark and sticky, the bleeding may have occurred higher up your digestive system.

This type of bleeding can turn your faeces black or plum-coloured (known as melaena).

Having plum-coloured, dark and sticky faeces may be a sign of a serious medical condition. You should see your GP urgently.

If you also feel unwell, with the symptoms of low blood pressure, contact your GP or the GP out of hours service immediately.

If the symptoms are very severe, phone 999 for an ambulance.

How your GP investigates rectal bleeding 

If your GP needs to examine you to find out what's causing your rectal bleeding, they may carry out a rectal examination. This involves putting a gloved finger inside your bottom (rectum).

There's no need to feel embarrassed or nervous. It’s a quick and painless procedure that GPs are used to doing.

Depending on your history and findings on examination, which will normally include a rectal examination, you may be referred to a hospital or specialist clinic if further examinations and tests are needed.

Bowel cancer

Many people with rectal bleeding worry they may have bowel cancer.

While rectal bleeding can be a sign of early-stage bowel cancer, other factors may also be present for your doctor to think you're at risk.

Depending on what your other symptoms are, or what your GP finds on examining you, you may be referred urgently to a specialist with suspected bowel cancer if:

• your GP has found an abnormality (such as a lump) after examining you 
• you are under the age of 50 (with rectal bleeding) and have any of the following:
  • abdominal (stomach) pain
  • change in bowel habit (how often you poo or you develop diarrhoea)
  • weight loss
  • iron-deficiency anaemia
• you are aged 40 and over with unexplained weight loss and abdominal pain
• you are aged 50 and over with unexplained rectal bleeding
• you are aged 60 and over with iron-deficiency anaemia or changes in your bowel habit
• tests show blood in your poo (that can’t be seen) - found on testing/screening tests

Your GP may offer further testing to find hidden blood in your motions (poo) if:

• you are aged 50 and over with unexplained, abdominal pain or weight loss, without rectal bleeding
• you are aged under 60 with changes in bowel habit or iron-deficiency anaemia without rectal bleeding
• you are aged 60 and over and have anaemia even without iron-deficiency or rectal bleeding

Your GP may consider further investigation if:

• you have a family history of bowel cancer
• you have ulcerative colitis

Bowel cancer is sometimes called colon or rectal cancer, depending on where the cancer starts.

Common causes of rectal bleeding 

Some of the most common causes of visible rectal bleeding in adults are outlined below.

Don't try to diagnose yourself. Always see your GP for a proper diagnosis.

Piles (haemorrhoids)

Piles (haemorrhoids) are 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

An anal fissure is 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

An anal fistula is 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 

Angiodysplasia is abnormal blood vessels in the gastrointestinal tract, which can cause bleeding. This is more common in older people and can cause painless rectal bleeding.

Gastroenteritis

Gastroenteritis is 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

Diverticula are 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

You should always get checked by your GP if you have rectal bleeding.

The only symptom of bowel cancer (colon or rectal 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 

Below are some of the more unusual causes of rectal bleeding.

Anticoagulant drugs

Anticoagulant drugs, such as warfarin or aspirin, which are taken to reduce your chance of a blood clot can sometimes cause internal bleeding.

Inflammatory bowel disease

Inflammatory bowel diseases, such as Crohn's disease or ulcerative colitis, can cause the lining of the bowel to become inflamed.

Crohn's disease affects the gut higher up, whilst ulcerative colitis affects the large bowel and rectum further down.

Both tend to cause bloody diarrhoea.

Bowel polyps

Bowel polyps are 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

Any sexual activity involving the anal area can spread Sexually transmitted infections (STIs), which may sometimes lead to rectal bleeding.

More useful links

• How to use your health services