A colonoscopy is a test where an operator looks into your colon. The colon is sometimes called the large intestine or large bowel. The colon is the part of the gut which comes after the small intestine. The last part of the colon leads into the rectum where faeces are stored before being passed out from the anus. A colonoscope is a thin, flexible telescope. It is passed through the anus and into the colon. It can be pushed all the way round the colon as far as the caecum. The colonoscope contains fibre-optic channels which allow light to shine down so the operator can see inside your colon. The operator may take a small sample (biopsy) from the inside lining of the colon by using a thin ‘grabbing’ instrument.
Who Needs a Colonoscopy?
A colonoscopy may be advised if you have symptoms such as bleeding from the anus, pains in the lower abdomen or persistent diarrhea. The sort of conditions which can be confirmed include:
- Ulcerative colitis (which causes inflammation of the colon).
- Crohn’s disease (which also causes inflammation of the colon).
- Diverticula (pouches which form in the lining of the colon).
- Polyps of the colon.
- Cancer of the colon.
What Happens During a Colonoscopy?
Colonoscopy is usually done as an outpatient or day case. You will usually be given a sedative to help you to relax. This is usually given by an injection into a vein. The sedative can make you drowsy but it does not ‘put you to sleep’. It is not a general anaesthetic. You lie on your side on a couch. The operator will gently push the end of the colonoscope into your anus and up into the colon. Air is passed down a channel in the colonoscope into the colon to make the inside lining easier to see. This may cause you to feel as if you want to go to the toilet. The air may also make you feel bloated, cause some mild ‘wind pains’, and may cause you to pass wind. This is normal and there is no need to be embarrassed, as the operator will expect this to happen. The operator may take biopsies (small samples) of some parts of the inside lining of the colon – depending on why the test is done. This is painless. The biopsy samples are sent to the laboratory for testing, and to be looked at under the microscope. Also, it is possible to remove polyps, which may be found, with an instrument attached to a colonoscope. (Polyps are small lumps of tissue which hang from the inside lining of the colon.) At the end of the procedure the colonoscope is gently pulled out. A colonoscopy usually takes about 20-30 minutes. A colonoscopy does not usually hurt, but it can be a little uncomfortable, particularly when the colonoscope is first passed into the anus.
What Preparation Do I Need?
You should get instructions from the hospital department before your test. The sort of instructions given include:
- The colon needs to be empty so that the operator can get a clear view. You will be instructed on how to take a special diet before the test. You will also be given laxatives to take.
- You will need somebody to accompany you home, as you will be drowsy with the sedative.
What can I Expect After a Colonoscopy?
Most people are ready to go home after resting for half an hour or so. You may need to stay a bit longer for observation if you have had any polyps removed. If you have had a sedative – you may take a bit longer to be ready to go home. The sedative will normally make you feel quite pleasant and relaxed. However, you should not drive, operate machinery, drink alcohol, take important decisions or sign documents for 24 hours after having the sedative. You will need somebody to accompany you home and to stay with you for 24 hours until the effects have fully worn off. The operator writes a report and sends it to the doctor who requested the colonoscopy. The result from any biopsy may take a few days. The operator may also tell you what they saw before you leave. However, if you have had a sedative, you may not remember afterwards what they said. Therefore, you may wish to have a relative or close friend with you who may be able to remember what was said.
Any Side-effects or Complications?
Most colonoscopies are done without any problem. The sedative may cause you to feel tired or sleepy for several hours afterwards. You may pass a small amount of blood from your anus if a biopsy was taken, or if a polyp was removed. You may also get leakage of liquid accompanied by gas for up to 24 hours after taking the last dose of laxatives: you should arrange your work/social activities following a colonoscopy with this in mind.
Occasionally, the colonoscope may cause damage to the colon. This may cause bleeding, infection and, rarely, perforation. If any of the following occur within 48 hours after a colonoscopy, consult a doctor immediately:
- Abdominal pain. (In particular if it becomes gradually worse, and is different or more intense to any ‘usual’ pains that you may have.)
- Fever (raised temperature).
- Passing a lot of blood from your anus.