Usually, you begin by seeing your GP (family doctor) who will feel your abdomen, and examine your back passage (a rectal examination). To do this, the doctor places a gloved finger into your back passage to feel for any lumps or swellings. This may be slightly uncomfortable but it is not painful. It will be less uncomfortable if you are able to relax while they are doing this. You may also be asked to take a sample of your stool (bowel motion) to the surgery so that it can be tested for blood.
If your GP thinks that your symptoms could be caused by cancer, or is not sure what the problem is, they will refer you to a hospital specialist. If a cancer is suspected you should be seen at the hospital within two weeks.
At the hospital the specialist will ask you about your general health and any previous medical problems, before examining you. They will repeat the rectal examination (as above).
The following tests may be used in the diagnosis of cancer of the large bowel.
These tests allow the doctor, or nurse colonoscopist, to look at the inside lining of the rectum or the large bowel. They will be done in the hospital outpatient department or on the ward.
You will be asked to lie curled on your left side while a tube is gently passed into your back passage. A small hand-pump is attached to the tube so that air can be pumped into the bowel. This makes you feel that you want to pass a bowel motion, but the feeling will gradually go away once the test is over.
A proctoscope is a short tube that just goes into the rectum. A sigmoidoscope is a longer tube that can be passed further up into the large bowel.
With the help of a tiny light and camera on the end of the tube, any abnormal areas can be seen. If necessary, a small sample of the cells (a biopsy) can be taken for examination under a microscope. The biopsy is not painful.
A proctoscopy or a sigmoidoscopy can be uncomfortable but is not usually painful. You should be able to go home as soon as the test is over.
If your doctor wants to look inside the whole length of the large bowel, you may have a colonoscopy. This will usually be done in the hospital outpatient department and takes about an hour.
For a colonoscopy the bowel has to be completely empty. This means following a careful diet for a few days before your test. The preparation is similar to that for the barium enema. You will be given instructions about this by your hospital.
Just before the test, you may be given a sedative tablet to help you feel more relaxed, which may make you feel sleepy during the colonoscopy. Once you are lying comfortably on your side, the doctor, or nurse, will gently pass a flexible tube (a colonoscope) into your back passage. The tube is made up of flexible fibres. It can easily pass around curves and most of the large bowel can be examined. A tiny light and camera on the end of the tube helps to show any abnormal areas or swelling.
During the test, photographs and samples (biopsies) of the cells on the inside of the large bowel can be taken. A colonoscopy can be uncomfortable but the sedative will help you feel more relaxed.
Most people are ready to go home a couple of hours after their test. It is a good idea to arrange for someone to collect you from the hospital as you shouldn’t drive for several hours after a sedative.
This is a special x-ray of the large bowel. It will be done in the hospital x-ray department.
It is important that the bowel is empty so that a clear picture can be seen. On the day before your test, you will be asked to drink plenty of fluids and to take medicine (a laxative) to empty your bowel.
On the morning of your enema, you should not have anything to eat or drink. This may vary slightly from hospital to hospital, but your doctor or nurse will give you an instruction sheet with advice.
Just before the test, to make sure that the bowel is completely clear, you may be given a bowel wash-out. The nurse will ask you to lie on your left side while a tube is gently passed into your back passage. Water is then passed through the tube. You will be asked to hold the liquid in the bowel for a few minutes before you go to the toilet.
For the barium enema, a mixture of barium (which shows up on x-ray) and air is passed into the back passage in the same way as the bowel wash-out. This ensures that a clear picture can be seen. It is important to keep the mixture in the bowel until all the x-rays have been taken. The doctor can then watch the passage of the barium through the bowel on an x-ray screen. Any abnormal areas can be seen.
The test can be uncomfortable and tiring, so it is a good idea to arrange for someone to travel home with you if possible.
For a couple of days after your enema, you may notice that your stools are white. This is the barium being removed from the body and is nothing to worry about. The barium can also cause constipation and you may need to take a mild laxative for a couple of days after your test.
An MRI (magnetic resonance imaging) scan uses magnetism to build up cross-sectional pictures of your body. It can help to show the stage of the cancer and can give the surgeon information to help them plan an operation or to decide whether radiotherapy can be given before surgery. People with a rectal tumour will often have an MRI scan before surgery.
Some people are given an injection of dye into a vein in the arm, to improve the image. During the test, you will be asked to lie very still on a couch inside a long chamber for about 30 minutes. This can be unpleasant if you don’t like enclosed spaces. If so, it may help to mention this to the radiographer. The MRI scanning process is very noisy, but you will be given earplugs or headphones to wear. The chamber is a very powerful magnet, so before going into the MRI room you should remove any metal belongings.
People who have heart monitors, pacemakers or certain types of surgical clips cannot have an MRI because of the magnetic fields.
This is a newer test that is also called a virtual colonoscopy.
It is not widely available, so if you need one you may have to travel to a specialist centre. Instead of having a colonoscope put into your bowel, a computer uses CT images to examine your bowel. Sometimes a CT colonography is done instead of a barium enema. It is still being researched as a way of diagnosing bowel cancers. Your doctor or nurse can discuss it with you further.
The preparation is the same as if you were having a colonoscopy, so you will be asked to drink fluids and take a laxative. CT colonography is done in the hospital CT department and can usually be done as an outpatient. Just before the CT scans are taken the doctor will pass a tube into your back passage (rectum) and pump in some air and gas (carbon dioxide). This expands up the bowel and helps to give a clearer picture. You will have two CT scans – one while lying on your back and one on your front. The computer then matches up the two scans to create a ‘virtual’ image of the inside of your bowel. You may still have a colonoscopy (see above) if biopsies are needed.