Rectal bleeding

Overview

Rectal bleeding means blood passed from your bottom. You may notice bright red blood on the toilet paper or in the toilet bowl, blood mixed in with your poo, or poo that looks dark red or black.

It is a common symptom and is often caused by something minor, but it should not be ignored. In most cases a doctor can find the cause with a short consultation and examination, and arrange a camera test if one is needed.

Common causes

Piles (haemorrhoids) are the most common cause. They typically cause bright red blood after a poo, and sometimes itching, discomfort or a soft lump around the bottom.

An anal fissure is a small tear in the skin of the back passage. It usually causes a sharp pain when you poo, often with a little bright red blood.

Bloody diarrhoea can be caused by a bowel infection (gastroenteritis), or by inflammatory bowel disease such as Crohn's disease or ulcerative colitis, especially if it keeps coming back.

Less commonly, bleeding comes from bowel polyps (small growths in the lining of the bowel) or from bowel cancer. Most polyps are harmless, but some can turn into cancer over time, which is one of the reasons bleeding is worth investigating.

Warning signs

Call 999 or go to A&E if you are bleeding non-stop, or there is a lot of blood — for example, the toilet water turns red or you see large blood clots.

Call NHS 111 or ask for an urgent GP appointment if your poo is black or dark red, or you have bloody diarrhoea.

See your GP if you have had blood in your poo for 3 weeks, a change in your bowel habit (such as looser poo or going more often) for 3 weeks, pain or a lump in your tummy, or you are losing weight or feeling very tired without a clear reason. Always get a child with blood in their poo checked by a GP.

How rectal bleeding is assessed

The doctor will ask about the bleeding — its colour, how often it happens and whether it is mixed with your poo — and about your bowel habit, weight, general health, family history and medicines. Blood-thinning medicines can make bleeding more noticeable, so bring a list of what you take.

They will usually examine your tummy and your bottom, including a gentle internal examination with a gloved finger. Sometimes they look just inside the back passage with a short, narrow instrument (a proctoscope). The examination is brief, and you can ask for a chaperone.

A blood test may be arranged to check for anaemia (a low blood count).

Investigations

In general practice, many people are asked to do a simple home stool test called FIT (faecal immunochemical test). It looks for tiny amounts of blood that cannot be seen, and the result helps decide whether, and how urgently, a specialist test is needed.

If the inside of the bowel needs to be looked at, the usual test is a colonoscopy, which examines the whole of the large bowel. Sometimes a shorter test of the lower bowel (flexible sigmoidoscopy) or a CT scan of the bowel is more suitable.

Colonoscopy

A colonoscopy uses a long, thin, flexible tube with a small camera to look inside the large bowel. You are usually awake, and are offered medicine to make you more comfortable. The test itself usually takes 30 to 45 minutes.

If polyps are found they can usually be removed during the test, and small tissue samples (biopsies) can be taken. You will not feel this. Our colonoscopy guide explains how to prepare, what happens on the day and how you will get your results.

Treatment

Treatment depends on the cause. Piles and fissures often settle with plenty of fluids and fibre to keep your poo soft and by avoiding straining. If they do not, creams, banding of piles or, occasionally, an operation can help.

Infections usually clear up on their own. Inflammatory bowel disease is treated with medicines and long-term support from a specialist team. Polyps are usually removed during colonoscopy and checked in the laboratory.

If bowel cancer is found, you will be seen quickly by a specialist team to plan your treatment. Cancer found early is much easier to treat.