The diagnosis of large bowel cancer

Usually, you begin by seeing your GP (family doctor) who will do an examination of your back passage and feel your abdomen. 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 a cancer may be present, or is not sure what the problem is, they will refer you to a hospital specialist.

At the hospital, the doctor will take your medical history before doing a physical examination. This will include a rectal examination. To do this the doctor places a gloved finger into your back passage to feel for any lumps or swellings. This examination may be slightly uncomfortable but it is not painful.

The following tests may be used in the diagnosis of cancer of the large bowel.

Barium enema

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 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.

Proctoscopy/Sigmoidoscopy

 This test allows the doctor, or nurse colonoscopist, to look at the inside of the rectum or the large bowel. It 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 light on the inside 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 not usually painful. You should be able to go home as soon as the test is over.

Colonoscopy / Flexible sigmoidoscopy

Colonoscopy 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 of the barium enema (described above). You will be given instructions about this by your hospital.

Just before the test, you may be given a tablet to help you feel more relaxed. 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 the whole length of the large bowel can be examined. A light on the inside 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.