What is a Colonoscopy?
Colonoscopy is a technique which allows examination of the inside of the large intestine and the last part of the small intestine. A thin flexible tube about the diameter of the index finger is inserted into the back passage and guided under direct vision around the colon. The inside of the colon or large intestine can be seen on a video screen and photographs can be taken.
The advantage of the colonoscope over barium enema is that it is more accurate and also allows specimens to be taken, if there are any signs of inflammation or suspicious areas which might suggest bowel cancer. Also polyps, which are benign growths in the colon, can be snared and removed. This is an important advancement since it is likely that most, if not all, cancers of the colon begin their early life as small benign polyps.
Is the procedure safe?
Colonoscopy, with or without the removal of polyps is regarded as safe and well tolerated. Polyp removal is known as polypectomy and as for any surgical technique both colonoscopy and polypectomy do have potential side effects of which you should be aware. These side effects might include perforation of the bowel and haemorrhage, but these complications are very rare and occur in less than one in 2000 – 3000 procedures.
The instruments are sterilised meticulously using a combination of manual cleaning and disinfection in an automated specially designed washing machine between patients. This is considered the world’s best practice and should ensure safety against transmission of bacteria and viruses such as HIV and Hepatitis B and C.
When is Colonoscopy indicated?
The major indications for colonoscopy are bleeding from the bowel, change in bowel habit, abdominal pain, or sometimes in screening relatives of patients with bowel cancer even in the absence of symptoms.
What special preparation do I require?
For maximum effect the colon needs to be cleansed of faecal material. A separate set of instructions will be given to you. The bowel preparation may cause dehydration or alternatively a drop in salt (sodium) and potassium levels in the blood.
This may cause headaches, dizziness or even collapse which can be serious. Therefore it is important that you consume fluids (not just water and fruit juices) which contain salts such as clear soups or electrolyte containing drinks as used by sports people.
Although colonoscopy is currently the best method available for examining the colon, as for any diagnostic test, in rare instances potentially important disease processes can still be missed. The colonoscopy is carried out either under sedation or a light general anaesthetic. The anaesthetic is short acting, but you should not drive for 24 hours after the procedure. You will be given separate instructions concerning fasting.
After the colonoscopy some excess wind and occasional mild colic may be noticed, but this wears off in a couple of hours. Any more significant symptoms such as bleeding or more severe abdominal pain should be reported to the nursing staff. If this occurs out of hours, you may need to attend the emergency department.