Colonoscopy

Published by Bupa’s Health Information Team, February 2011.

This factsheet is for people who are having a colonoscopy, or who would like information about it.

A colonoscopy is a procedure that allows the doctor to look inside the large bowel (colon and rectum) for polyps, bowel disease or signs of cancer.

You will meet the doctor carrying out your procedure to discuss your care. It may differ from what is described here as it will be designed to meet your individual needs.

About colonoscopy

A colonoscopy is an investigation used to look at the lining of your large intestine. It is performed using a narrow, flexible, telescopic camera called a colonoscope. Your doctor will pass the colonoscope into your bowel through your anus (back passage).

A colonoscope can help your doctor to find out what is causing symptoms such as:

• persistent diarrhoea or a change in your bowel habit
• bleeding from your rectum
• anaemia – a condition where you don't have enough red blood cells to transport the oxygen around your body

It's also used to check for:

• inflammation caused by conditions such as ulcerative colitis or Crohn's disease
• signs of bowel cancer
• polyps (small growths of tissue, sometimes called adenomas)

Sometimes, a colonoscopy is used to confirm the results of other tests, such as a barium enema. You may also be asked to have a colonoscopy if you have had an abnormal faecal occult blood (FOB) test as part of routine bowel cancer screening.

During the procedure, your doctor may take a biopsy (sample of tissue) for examination in a laboratory. He or she may also remove any polyps found on your bowel wall. Polyps are usually benign (not cancerous), but they can change into cancer over a number of years.

What are the alternatives?

A colonoscopy is usually the best investigation for showing the inside of your bowel. However, it isn’t appropriate for everyone. If you can’t have a colonoscopy then your doctor may suggest other tests. The main alternatives are listed below.

• Barium enema. A fluid containing barium (a substance which shows up on X-rays) is put into your bowel via your anus. X-ray images of your abdomen (tummy) are taken which show the inside of your bowel.
• Virtual colonoscopy. This test involves having a CT scan of your abdomen. A CT scan uses X-rays to produce three-dimensional images of your lower bowel and rectum.
• Flexible sigmoidoscopy. This is a similar procedure to a colonoscopy but it uses a shorter instrument to look inside your rectum and the lower part of your bowel.

Preparing for a colonoscopy

Colonoscopy is usually done in hospital as a day-case. This means you have the test and go home the same day.

Your hospital will write to you telling you what you need to do before your colonoscopy. You will usually need to begin preparing two days before your test.

Your bowel needs to be completely empty during the test so that your doctor can see clearly. You will usually be asked to:

• stop taking any iron tablets – these make the inside of your bowel look black, which makes it hard for your doctor to see clearly
• eat a special diet in the days before your test
• drink lots of clear fluids before your test – at least six to eight glasses a day
• take strong laxatives – these can be quite powerful and will give you diarrhoea, so you will need to stay close to a toilet

If you normally take medication, for example tablets for high blood pressure, take them as usual, unless your doctor tells you not to. He or she may ask you to stop taking some of your usual medicines if they are likely to make you constipated. If you take medicines that affect the way your blood clots, such as warfarin or clopidogrel, tell the outpatient department staff when you receive your appointment letter. The staff will tell you whether you need to stop these before the test.

If you have diabetes and you’re taking insulin or medicines to treat it, contact the outpatients department to tell them. They can arrange for you to be first to have your colonoscopy on the day of your appointment. You will be given specific information about when to take your medicines or insulin and what to eat before the procedure.

Your doctor will discuss with you what will happen before, during and after your procedure, and any pain you might have. This is your opportunity to understand what will happen, and you can help yourself by preparing questions to ask about the risks, benefits and any alternatives to the procedure. This will help you to be informed, so you can give your consent for the procedure to go ahead, which you may be asked to do by signing a consent form.

What happens during a colonoscopy

The procedure usually takes 30 to 60 minutes to complete.

Your nurse will ask you to put on a hospital gown that opens at the back.

You will probably be given a sedative and a painkiller before your colonoscopy, to make sure you're relaxed and comfortable during the procedure. These medicines are usually given through a small plastic tube which goes into a vein in the back of your hand. If you have a sedative, you won't remember much about the test.

You may have an oxygen sensor clipped to your finger to monitor how well you are breathing and you will be asked to wear an oxygen mask. Your pulse and blood pressure may also be recorded during the procedure. Your doctor will ask you to lie on your left side and he or she will gently insert the colonoscope into your rectum. Lubricating jelly will be used to make this as easy as possible.

Air is pumped into your bowel to make it expand slightly, which makes the colonoscope pass through your bowel more easily. When this happens, it might feel uncomfortable and you may pass some wind. Your doctor will gently move the colonoscope up through your bowel. The colonoscope is flexible and the doctor can rotate the tip pf the instrument so that it follows the curves in your bowel.

A camera lens at the end of the colonoscope sends images to a monitor; you may be able to see the monitor too if you wish. Your doctor will look at these images to examine your bowel. During the procedure, you may be asked to change your position – for example turning from your side on to your back. This helps your doctor to examine different areas of your bowel.

During the procedure your doctor may take a biopsy or remove small polyps. This is done using special instruments passed inside the colonoscope, and is quick and painless. The samples will be sent to a laboratory for testing to see if the cells are benign or malignant (cancerous).

When the test is finished the colonoscope is withdrawn quickly and easily, while sucking out the air that has been introduced during the procedure.

What to expect afterwards

You will need to rest until the effects of the sedative have passed. You will usually be able to go home when you feel ready. You will need to arrange for someone to drive you home. Try to have a friend or relative stay with you for the first 24 hours after your colonoscopy.

If you have had a biopsy or had polyps removed, your results will be sent to the doctor who recommended your test. At the hospital, your doctor may discuss other findings from the colonoscopy with you before you leave, or you may be given a date for a follow-up appointment.

Recovering from a colonoscopy

If you need pain relief, you can take over-the-counter medicines, such as paracetamol or ibuprofen. Always read the patient information that comes with your medicine and if you have any questions, ask your pharmacist for advice.

Sedation temporarily affects your co-ordination and reasoning skills, so you must not drive, drink alcohol, operate machinery or sign legal documents for 24 hours afterwards. If you’re in any doubt about driving, contact your motor insurer so that you’re aware of their recommendations, and always follow your doctor’s advice.

Most people have no problems after a colonoscopy, but you should contact your doctor if you:

• have heavy bleeding from your back passage
• have a swollen abdomen and abdominal pain that gets worse
• feel unwell and develop a fever (high temperature)

What are the risks?

As with every procedure, there are some risks associated with colonoscopy. We have not included the chance of these happening as they are specific to you and differ for every person. Ask your doctor to explain how these risks apply to you.

Side-effects

These are the unwanted, but mostly temporary effects you may get after having the procedure.

After having a colonoscopy you may feel bloated and uncomfortable due to trapped wind. You may find that lying on your front can sometimes help. Trapped wind usually passes after a few hours. You may also bleed a little from your back passage if you have had a biopsy or polyp removed.

Complications

Complications are when problems occur during or after the procedure. Most people aren't affected. However, sometimes complications do occur. The main ones are listed below.

• Your doctor may not be able to see all of your bowel. This can happen if your bowel isn’t empty or the colonoscope can’t be passed round a curve. If this happens you may need to have the colonoscopy done again, or have other tests.
• You may have a reaction to the sedation, which can affect your breathing or your heart. You will be monitored throughout the procedure and treated quickly if any of these problems develop.
• The colonoscope and the other instruments used during the procedure can damage or tear your bowel. If this happens you may need an operation to repair it.
• You may have heavy bleeding if you have had biopsies or polyps removed.

For answers to frequently asked questions on this topic, see Common questions.

For sources and links to further information, see Resources.