What is a colonoscopy?
A colonoscopy is a test used to examine the colon, an area of the body which is also known as the bowel or large intestine. A colonoscopy involves using a thin, flexible tube known as a colonoscope to examine the inside of the colon, which allows doctors to see inside the large intestine and detect symptoms and signs of potential abnormalities, health conditions and damage.
The colonoscope is around the same thickness as a finger and is put in the anus, up the back passage and guided up to the bowel. A colonoscope can be used to look around the entire colon but a sigmoidoscopy may be recommended if doctors want to see the rectum as well as the lower portion of the colon. The colonoscope has fibre optic sections that enable doctors to see the colon in the light. Devices can also be attached for removing tissue samples, for example.
Why would I need a colonoscopy?
A colonoscopy is a useful test used in the diagnosis of several different conditions. You may be advised to have a colonoscopy if you have symptoms that suggest any of the following conditions:
- Ulcerative colitis (this is when ulcers form in the colon and the colon is swollen).
- Crohn’s disease (this can cause the colon to be inflamed).
- Polyps in the colon.
- Cancer of the colon.
- Diverticula (these are small pouches that protrude from the side of the colon).
Preparing for a colonoscopy
You will receive a letter from the hospital giving you information about the procedure, including the date, where you need to go, what time you need to be there and any steps you need to take to prepare for the test. It is important that the colon is empty when you have the colonoscopy, so you will be advised to follow a special diet and take laxatives for a short period of time before the test. You will also be advised to arrange for somebody to give you a lift home, as you may feel drowsy after the procedure. If you have any questions about the test or need more information, do not hesitate to talk to your doctor.
In most cases, a colonoscopy is carried out as an outpatient procedure. The actual test only takes a short period of time, but you will need to turn up in plenty of time. Before you have your test you will be given a sedative to help you to relax. The sedative will not put you to sleep like a general anaesthetic, but it will make you feel calm and comfortable throughout the procedure.
When you are ready for your test, you will be asked to sit on a couch and lie down on your side. The colonoscope will then be passed through your anus and up into the colon. The operator will guide the colonoscope around the colon and the device will send images to a television monitor, which enables the doctor to see images of your colon clearly.
During the test, air will be passed into the colon to make it easier to see inside. This may make you feel a little uncomfortable, like you have got wind or want to go to the toilet, but it will not be painful. If you do pass wind this is nothing to be embarrassed about and the operator will be expecting you to do this as a result of the air inside your colon.
The operator may take some tissue samples during the test (these are known as biopsies) and once the samples have been removed, they will be sent to the laboratory for analysis. A colonoscopy usually lasts around 20-30 minutes but you will need to stay in hospital for a short time after (usually around half an hour) because you will feel drowsy after taking a sedative.
After the colonoscopy
A colonoscopy may cause discomfort but it should not be painful. However, if you do experience pain tell your doctor. If you have been sedated you will feel drowsy and tired after the procedure, and it is important that you avoid driving and heavy lifting for 24 hours after the test. It is also a good idea for somebody to stay with you for 24 hours after the test to help you around the house. The operator may talk to you about what they saw on the test. If you have had a sedative, you may not really be aware of what is going on and may want a friend or relative to talk to the operator for you. The operator will write a report based on the findings of the test and this will be sent to a doctor. The test results will take longer to come through if you have had biopsies removed, as it takes time for the samples to be analysed.
Are there any risks or side-effects?
A colonoscopy is a very safe procedure and complications are rare. After the test the sedative may cause you to feel weary and tired for several hours, and if you have had a biopsy removed, this may cause a small amount of bleeding from the anus. It is important that you seek medical help if you develop any of the symptoms listed below within 48 hours of a colonoscopy:
- Abdominal pain (especially if it gets worse).
- Bleeding a lot from the anus.
These symptoms may also indicate damage to the colon.