Bowel cancer tests

• A quick guide to what's on this page
• Seeing your GP
• Rectal examination
• At the hospital
• Sigmoidoscopy and proctoscopy
• Colonoscopy
• Barium enema
• Virtual colonoscopy (CT colonography)
• After your tests

Usually you begin by seeing your GP who will ask you about your general health and may examine your back passage (rectum). This is called a rectal examination. You may have a blood test to check for anaemia. Anaemia is common in people with colorectal cancer but may also occur due to other conditions. You may also have blood tests to check if your liver and kidneys are working normally. Your GP may then refer you to hospital for further tests or X-rays. You may have some of the other tests mentioned below.

Your GP or the specialist at the hospital may do a rectal examination. They do this by putting a gloved finger into your back passage (rectum) and feeling for any lumps or swellings. The examination may be slightly uncomfortable, but should not be painful.

The bowel cancer specialist will ask about your medical history and your symptoms, and will probably want to examine your back passage (rectum). You may have this done in the clinic with a sigmoidoscopy. You may also have the rest of your bowel examined with a colonoscopy or barium enema.

These tests allow the doctor or a specialist nurse to look inside the rectum (proctoscopy), or the lower part of the large bowel (sigmoidoscopy). You usually have this test in the outpatient department. You don't usually need any anaesthetic, or anything to make you drowsy. To have a sigmoidoscopy, you must have an empty lower bowel. You are usually given a small enema or strong laxatives beforehand to clear the bowel out.

Once at the hospital, you may be asked to change into a hospital gown. You may also have paper trousers, with a hole cut out of the back, under your gown. Then, you will be asked to lie on the couch on your left side. The doctor or nurse puts a thin tube called a sigmoidoscope into your back passage (rectum) and up into the large bowel. This is usually painless, but if you find it too uncomfortable at any stage, just tell the doctor or nurse and they will stop. Once the tube is in place, a little air or carbon dioxide is pumped into your bowel. This inflates the bowel slightly and helps the doctor or nurse to see the bowel wall more clearly.

If you have any abnormal areas the doctor or nurse can take samples (biopsies) with the sigmoidoscope. If you have any polyps, the doctor or nurse will snip these off and send them away to be examined under a microscope. The whole procedure takes about 5 minutes. It may take a little longer if you need to have polyps removed, but even then the test only takes about 10 to 15 minutes.

You should be able to go home as soon as the test is over. Some people have a small amount of bleeding from the back passage after sigmoidoscopy, particularly if they have had polyps removed. This is normal and usually clears up on its own over a few days.

This test looks at the whole of the inside of the large bowel. It is done in the outpatient department and takes about an hour.

For this test the bowel has to be empty. You will be given a list of things to do to help prepare the bowel for the test. These are likely to include

• Stopping iron tablets
• Not eating solid food for 2 days before the test
• Drinking plenty of clear fluids
• Taking laxatives

When you arrive at the hospital, the nurse or technician will ask you to remove your clothes and will give you a gown to change into. You may also have paper trousers, with a hole cut out of the back, to wear under your gown. You will probably have medicine to make you drowsy just before the test. This is called a sedative. Colonoscopy is nearly always done with sedation and painkillers because it would be uncomfortable without them. It may be possible to have a colonoscopy without a sedative, if you have particular reasons for wanting to. You would need to talk to your doctor beforehand about this.

Your doctor will ask you to lie on your side and will pass a flexible tube into your rectum and up into your bowel. As the tube bends easily, it can pass around the curves in the bowel so your doctor can examine the whole length of your bowel. The light inside the tube helps the doctor to see any problem areas or swelling. Photographs and biopsies of the bowel lining can be taken during the test. Your doctor may also spray a dye onto the lining of the bowel to make abnormal areas show up more clearly. This is called chromoscopy.

You should be able to go home a couple of hours after the test. You shouldn't drive for a few hours after the sedative. If you have had a sedative, you should have someone with you to take you home. Ideally they should stay overnight just to make sure that you are alright.

Colonoscopy is a very safe test. But like all medical tests, it does have its risks. There is a very small risk of tearing the bowel wall. Your doctor may call this 'perforation'. This only happens in about 1 out of every 800 colonoscopies at most. But we have mentioned it because it is a serious complication for the very few people it affects. If you have a perforation, you would have to go to the operating theatre for emergency surgery to repair your bowel wall. And you would need strong antibiotics for abdominal infection.

This is an X-ray of the large bowel. For this test you have to have an empty bowel. You will be

• Given laxatives to take the day before
• Asked to drink lots of fluids the day before
• Asked not to eat solid food on the day before the test
• Asked not to eat and drink anything on the morning of the test

When you arrive at the hospital, the nurse or technician will ask you to change into a gown. You may also have paper trousers, with a hole cut out of the back, to wear under your gown. Before the test, you may have a bowel washout, although this isn't usually needed because laxatives generally work very well. A bowel washout is a bit like having an enema. A tube is passed into your rectum and water is passed through the tube. The water then drains out of the tube again into a bowl or bucket. As the water drains out, it washes out the inside of the bowel.

Barium is a white liquid which shows up on X-rays. A mixture of barium and water is passed into the rectum in the same way as the bowel washout. But you will be asked to try to hold the liquid in the rectum this time, until all the X-rays have been taken.

The barium passes through the bowel and shows up any lumps or swellings. The doctor can watch on an X-ray screen.

The test can be uncomfortable and tiring. It is best to have someone to take you home afterwards. After the test

• You may be constipated
• Your first couple of stools will be white

You may want to ask the doctor for a mild laxative to take home with you after the test. Your stools will go back to normal after the barium is out of your system.

This is a new type of test. It is also called CT colonography. Instead of having the colonoscope put inside your bowel, you may be able to have an examination with pictures created by a computer. This is a new type of test and so not all radiologists are trained and experienced in using it yet.

The preparation is the same as for barium enema - laxatives and plenty of fluids to clear out your bowel. The test is done with a CT scanner. So you have this test in the CT scanning department. You can have it as an outpatient.

Just before the test, the doctor will put a small tube into your back passage to pump air or carbon dioxide inside. This helps to open up the bowel, which gives a better result from the scan. You then have two CT scans done. One when you are lying on your back and one lying on your front. A computer matches up the two scans and makes a 'virtual' scan of the inside of your bowel. This shows up any growths on your bowel wall. You may still need to have a colonoscopy if a biopsy is needed.

CT colonography is sometimes used instead of a barium enema to examine the bowel. Clinical trials are comparing it to standard tests to see if it is as good as barium enemas at helping to diagnose bowel cancer. There is more information about this in the 'what's new in bowel cancer' section of CancerHelp UK.

After your tests for bowel cancer, you usually go back to the hospital to get your test results. This is bound to take a little time, even if only a week or so. Understandably, this is a very anxious time for most people.

While you are waiting for results it may help to talk to a close friend or relative about how you are feeling. Or you may want to contact a cancer support group to talk to someone who has been through the same experiences.

Look at the bowel cancer organisations page for organisations that can put you in touch with a support group. There are also details of organisations who can tell you more about counselling and help you to find sources of emotional support and counselling in your area.