Page last reviewed: 13/07/2011
Rectal bleeding (bleeding from the bottom) is usually caused by a swollen blood vessel or a small tear around the anus. However, it can have a more serious cause and should never be ignored.
You should always get rectal bleeding checked by your GP to rule out more serious causes.
Most people with rectal bleeding will see small amounts of bright-red blood on the toilet paper after they have been to the toilet, or a few droplets that turn the water in the toilet pink. These are typical signs of piles (haemorrhoids) or a small tear (anal fissure) in the skin of your anus, the opening through which stools pass. Both are very common problems.
In general, bright-red blood means the bleeding has come from somewhere near your anus.
If the blood is darker in colour or black and sticky, the bleeding may have occurred higher up your digestive system.
Your age, and whether you have any other symptoms (see below), are major clues to the cause of bleeding.
Below are the most common causes of visible rectal bleeding in adults. However, do not try to diagnose yourself, and always see your GP for a proper diagnosis.
Many people with rectal bleeding worry they may have bowel cancer. While rectal bleeding is a sign of early-stage bowel cancer, other factors are usually also present for your doctor to think you're at risk.
You will be urgently referred to a specialist with suspected bowel cancer if you have rectal bleeding and:
- you are aged 40 or older and have passed looser or more frequent stools for the last six weeks
- you are aged 60 or older and the bleeding has lasted for six weeks or more
- your GP has found an abnormality (such as a lump) after examining you
- you also have anaemia, a reduced number of red blood cells
Common causes of rectal bleeding
Click on the links below for more information on the most common causes of rectal bleeding.
Piles 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.
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.
Gastroenteritis is a viral or bacterial infection of the stomach and bowel, which your immune system will usually fight off after a few days. It can cause diarrhoea that contains traces of blood and mucus, as well as other symptoms such as vomiting and stomach cramps.
Diverticular disease is where small bulges form 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).
Colon cancer and polyps
Colon cancer (a type of bowel cancer) is a common cancer and the reason why you should always get checked by your GP if you have rectal bleeding. The only symptom may be rectal bleeding in the early stages, so don't ignore it.
Colon cancer starts as little growths called polyps, and removing these early can prevent the cancer taking hold.
Cancer of the rectum
Cancer of the rectum is a type of bowel cancer that usually affects older people, but can only be ruled out after seeing your GP (see above).
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.
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 rectum (bottom).
There’s no need to feel embarrassed or nervous: it’s a quick and painless procedure that GPs are used to doing.
The examination usually takes one to five minutes, depending on whether your GP finds anything unusual.