Bowel cancer tests
This page tells you about tests for bowel cancer (also called colon cancer or colorectal cancer). You can find the following information
Bowel cancer tests
Usually you begin by seeing your GP, who will ask about your general health, examine you and do some blood tests. They may examine your back passage (rectum). Your doctor may then refer you to hospital to see a specialist and for further tests.
At the hospital
A bowel specialist will ask about your medical history and symptoms. The doctor or a specialist nurse can use a tube to look inside the back passage and lower part of the large bowel. This test is called a sigmoidoscopy. You usually have this done in the outpatient department. To have a sigmoidoscopy, you must have an empty lower bowel. You usually need to have a small enema or strong laxatives beforehand to clear your bowel out.
If they can see any abnormal areas, the doctor or nurse will take samples (biopsies). If you have any growths of the bowel lining (polyps), they will remove them and send them away to be looked at under a microscope.
Your doctor may advise you to have a colonoscopy. This test looks at the whole of the inside of the large bowel. You have it in the outpatient department and it takes about an hour. For this test the bowel has to be empty. You will probably have medicine to make you drowsy just before the test. The doctor or nurse will ask you to lie on your side and will pass a flexible tube into your back passage and up into your bowel. They can take photographs and biopsies of the bowel lining during the test.
In some cases, your doctor may arrange for you to have a CT colonography (virtual colonoscopy). This uses CT scans to look at the inside of the large bowel. Occasionally you may have a barium enema, which shows an outline of the bowel using X-rays.
You can view and print the quick guides for all the pages in the diagnosing bowel cancer section.
Usually you begin by seeing your GP who will ask 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 bowel cancer but may also be caused by other conditions. You may have blood tests to check if your liver and kidneys are working normally. Your GP may then refer you to hospital to see a specialist and for further tests.
Read about what happens and what you can do if your GP makes an urgent referral for you.
The bowel specialist will ask about your medical history and symptoms, and will probably examine your back passage. You may have this done in the clinic with a sigmoidoscopy, which examines the back passage and the lower part of your bowel. The specialist may also want to examine the rest of your bowel with a colonoscopy.
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 and feeling for any lumps or swelling. The examination may be uncomfortable but should not be painful.
This test allows the doctor or a specialist nurse to look inside your back passage and lower part of the large bowel. They use a thin tube which has a light and camera on one end. They can see the pictures of the inside of your bowel on a TV screen. The test takes around 5 to 15 minutes.
To have a sigmoidoscopy you must have an empty lower bowel. So you usually need to have an enema or take strong laxatives beforehand. Your doctor or nurse may arrange for you to do this at home the day before or the morning of your test.
You usually have sigmoidoscopy in the outpatient department. You don't usually need an anaesthetic or medicine to make you drowsy.
If the doctor or specialist nurse can see any abnormal areas in your lower bowel they will take samples (biopsies). If you have any growths of the bowel lining (polyps) they will snip these off and send them away to be looked at under a microscope.
Read more about having a sigmoidoscopy.
A colonoscopy looks at the whole of the inside of your large bowel.
A doctor or specialist nurse uses a flexible tube which has a small light and camera at one end. They put the tube into your back passage and gently pass it along the bowel. They can see the pictures of the inside of your bowel on a TV monitor. The doctor or specialist nurse can take samples from the bowel lining and remove any polyps. These are sent to the laboratory to be looked at.
Below is an animation showing what to expect when you have a colonoscopy.
View a transcript of the video about having a colonoscopy (opens in a new window).
You usually have a colonoscopy as an outpatient. Before having the test, a nurse will offer you medicine to make you drowsy (sedation). In some hospitals you may have gas and air (Entonox) instead. The test takes about half an hour, but you should expect to be in hospital for a few hours.
You need to have an empty bowel to have this test. So you will take laxatives the day before your appointment. You also have to follow a special diet for 1 or 2 days beforehand. The hospital will give you strict instructions on what you have to do. It is important that you follow these carefully.
Read more about having a colonoscopy.
CT colonography is also called virtual colonoscopy. Instead of having the colonoscope put inside your bowel, the doctor looks at pictures created by a computer.
Before the test you have laxatives and plenty of fluids to clear out your bowel. You also follow a special diet for a couple of days beforehand. Your doctor or nurse will give you full details. The test uses a CT scanner, so you have this test in the CT scanning department. You can have it as an outpatient.
The scan shows up any growths on your bowel wall. You may still need to have a colonoscopy if you need a biopsy.
Read about having a CT colonography.
This is an X-ray of the large bowel. Doctors occasionally use it instead of CT colonography.
Barium is a white liquid that shows up clearly on an X-ray. The barium coats the inside of the large bowel and rectum, and shows the outline on the X-ray. This can show any growths or abnormal areas. If you need a biopsy, you will need to have a colonoscopy.
Read about having a barium enema.
After your tests for bowel cancer you usually go back to the hospital to get your 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 a similar experience.
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 that can tell you more about counselling and help you to find sources of emotional support and counselling in your area.
Rated 5 out of 5 based on 315 votes
Question about cancer? Contact our information nurse team