A Colonoscopy involves the examination using a fibre-optic flexible tube of the entire colon (large bowel). The large bowel is about 1.5m in length and is responsible for the absorption of water and the formation of stool. It also has some other important functions such as the absorption of vitamin K.
If you have symptoms of rectal bleeding, haemorrhoids, diarrhoea, alternating bowel habit (constipation and diarrhoea), weight loss, anaemia, suspected bowel cancer, bloating and abdominal pain you may require this procedure.
What does the procedure involve?
Specific instructions prior to the procedure will be provided to suit each individual surgeon's preferences, which may be based on your symptoms. The day before the procedure you will be provided with bowel preparation to drink, which will clear your large bowel of stool. You will also be given dietary advice before the procedure as well. The bowel preparation is designed to clear your large bowel of faeces and requires you to be at home if possible as you may experience diarrhoea. You are encouraged to drink plenty of fluids to prevent dehydration.
For the procedure you will lie on your left hand side with your hip and knees bent. Sedation as well as pain killers (pethidine or morphine) is given to all patients at the start and the colonoscope is passed through your anus with a small amount of air introduced to inflate the bowel so your surgeon can accurately visualise your colon. A tissue sample, biopsy may be taken, as well as removal of any polyps that may be found. During the procedure you may experience cramp like abdominal pain and bloating as the air is introduced, but this is temporary and resolves after the procedure is completed. In addition the surgeon may need to move you to lie on your front or back which aids in the passage of the endoscope through your colon.
The procedure normally takes 20 to 30 minutes and you must ensure that someone accompanies you, as you will have sedation.
After the procedure you may experience some bleeding, but this should settle after a few days. You must inform us of any untoward bleeding or abdominal pain.
What are the main risks:
1) Bleeding (1:100-200) patient especially if a polyp has been removed or a biopsy perfomed.
2) Perforation (1:1,000)
Virtual colonoscopy involves the examination of the entire colon using computer tomography (CAT) scanning. A special computer enables the images to be put together to give an image of the inside of the bowel.
Its use is the same as for colonoscopy but only takes about 10 minutes and does not require sedation.
What does the procedure involve?
As for colonoscopy bowel preparation is required to clear the bowel out to enable good visualisation of the colon. Patients will lie face up on an X-Ray table with a thin tube inserted through the anus and into the rectum. In order to visualise the colon carbon dioxide is used to inflate the colon. The table is rotated and you pass through the CAT scanner so that various images are taken with the final images taken with you lying flat face down. An advanced computer program on the CAT scanner will then create a three-dimensional image of the colon, which is interpreted by a Consultant radiologist.
This procedure is safer than a colonoscopy as it does not require the direct endoscopy, which involves sedation and a small risk of perforation. However, it does not allow the removal of any polyps or taking of any tissue samples, biopsy. In addition smaller polyps (less than 5mm in diameter) may be missed. This makes virtual colonoscopy purely diagnostic.