Blood in faeces

Rectal bleeding can be caused by many reasons. Most commonly there will be only a mild bleeding, only on rare occasions can it be life-threatening. You should see a doctor immediately if the bleeding is heavy, or if you have black faeces (bleeding in the stomach or duodenum, known as melaena). If it is a mild bleed then you should not panic and make an appointment with your doctor for a diagnosis of the problem.

Rectal bleeding will often be used by doctors to mean any blood that passes out when you go to the toilet. Not all blood that can be passed will come from the rectum. In fact it can come from anywhere in your gut (gastrointestinal tract). The correct term is gastro-intestinal tract bleeding, or 'GI' bleeding.

If you have bleeding your doctor will need to asses the cause and severity of the bleeding. In most cases the bleeding will be mild and tests can be done as an outpatient as there is no immediate risk to life with a mild bleed. Always report to your doctor if you have a large amount of bleeding, urgent treatment is required for a large amount of blood loss.

Sometimes the bleeding from a gut condition can be mild, in which case you may not notice any bleeding and your faeces may not change colour. A test of your faeces will detect even small amounts of blood.

Bleeding could come from anywhere in the GI tract, generally:

Bleeding in the anus or rectum, the blood will be bright red and fresh.  You may notice blood after passing faeces and not mixed mixed in with the faeces. You may also notice streaks of blood covering faeces.

Bleeding from the colon, the blood may be mixed in with the faeces. The blood may also be darker red in colour.

Bleeding from the stomach or small intestine. The blood will have further to travel through the gut, the blood will become darker and can mix in the faeces. Your faeces may turn black or a plum colour, this is called melaena. This may occur due to a bleeding stomach. If you have melaena it is an emergency and can indicate a lot of bleeding from the stomach. You should contact your doctor immediately if you suspect that you have melaena.

Your doctor will ask questions to determine the possible causes of the bleeding. You may be asked questions regarding the symptoms such as pain, and the location and nature of any pain. If you have other symptoms such as diarrhoea or weight loss you should make these known to your doctor. Any mention anything else which you are aware of. An examination is likely to take place, this can involve your doctor examining your anus and rectum by inserting a gloved finger into your anus. Its possible that the diagnosis can be made after this examination. Test are commonly needed to clarify the initial diagnosis.

Some of the common causes of blood in the faeces are:

Haemorrhoids (piles). These are swellings that occur in the lower rectum and anus. Within the inside lining of the lower rectum and anus is a network of small veins. Sometimes these veins can be wider and engorged with more blood than usual. The engorged veins and surrounding tissue may then form in small swellings called haemorrhoids. About 50% of the people in the UK develop haemorrhoids at some stage. Small ones are usually painless. Larger ones may cause a mucus discharge, some pain, irritation and itching.

An anal fissure is a small tear in the skin of the anus. Generally this tear is less than a centimeter in length however can be very pain due to the sensitivity of the anus. An anal fissure will bleed a little after you pass faeces. This blood will be bright red and stains the toilet tissue, but soon stops.

A diverticulum is a small pouch with a narrow neck that sticks out from the wall of the gut. They can develop in any part of the gut, but generally occur in the colon. A diverticulum may occasionally bleed and you may pass some blood from your anus. The bleeding is due to a burst blood vessel that sometimes occurs in the wall of a diverticulum.

Crohn's disease is a condition that will cause inflammation in the gut. The disease flares up from time to time. Common symptoms include bloody diarrhoea, abdominal pain and general unwell feeling.

Ulcerative colitis is a disease of the colon and rectum, causing inflammation to occur. A common symptom is blood mixed with diarrhoea. The blood comes from ulcers that develop on the inflamed guts inner wall.

A bowel polyp (adenoma) forms on the inside lining of the rectum or colon and is a small growth. These mainly occur in older people. Aproximately 25% of people over the age of 50 develop at least one bowel polyp. They are non cancerous and usually will cause no problems. On rare occasions a polyp bleeds and can turn cancerous.

Cancer of the rectum and colon are common cancers in older people. Rectal bleeding is one symptom that could occur. Other symptoms may present themselves before visible bleeding occurs. For example pain, anaemia, weight loss, diarrhoea or consipation.

Angiodysplasia is a condition where enlarged blood vessels develop within the inner lining of the colon. The cause is unknown and commonly occur in older people. Bleeding from angiodysplasia in painless. The visible blood can range from bright red to dark blood mixed with faeces, to melaena (black faeces).

Various abnormalities of the gut or gut wall may cause rectal bleeding in your children.

An ulcer of the stomach may bleed and may cause melaena.

A gut infection may cause bloody diarrhoea due to the infection causing an inflammation of the gut.

If you have rectal bleeding and it is heavy bleeding or if you have melaena then you should seek medial assistance urgently. If you are feeling dizzy or collapse then you should contemplate calling an ambulance. For mild bleeding you should make an appointment to see your doctor. Some people will assume that rectal bleeding is due to haemorrhoids and do not consult a doctor. You should not assume that it is related to haemorroids and should seek a proper medical examination from a doctor.

Depending on the possible cause of the bleeding, common test would include a colonoscopy or sigmoidoscopy. A colonoscopy is a test where a small camera is inserted into the anus and into the colon. It is about as thick as a finger and will allow the doctor to see inside your colon. A small biopsy may also be taken for further analysis. A sigmoidoscopy is a similar examination however the lower colon or rectum is examined and is easier to perform than a full colonoscopy.

A faecal occult blood test (FOB) will detect small amounts of blood in your faeces which you may not normally see or detect. Some disorders will only leave a small trace of blood in the faeces. A FOB test will detect small amounts of blood, however it will not detect where the blood is coming from. A small sample of faeces will be smeared onto a piece of card, this may be done in the doctors surgery and sent away to a lab for testing. You can be issued with a home test kit for performing this at home. Sometimes more than one test will be performed due to some bleeding disorders that only bleed now and then.

You should always seek expert medical advice from your doctor if you are concerned about finding any blood in your faeces.