Colonoscopy is a procedure which allows the doctor to examine the inside of your rectum and your large bowel (colon). The instrument used is a colonoscope – a long, flexible tube about 11-13 mm in diameter (about the thickness of your index finger), with a camera at the end which relays images back to a TV screen. Unlike X-rays which take “photographs” colonoscopy lets the doctor see the surfaces inside your bowel directly and can provide more detail and accuracy than an X-ray. In certain cases treatment is possible thereby avoiding an operation. It allows for a variety of operations to be carried out through the colonoscope. These operations may include taking small tissue samples (biopsy) and removal of polyps. This is achieved using long, thin forceps which are passed through the colonoscope. As cancer of the large bowel arises from pre-existing polyps (a benign wart-like growth), it is advisable that if any polyps are found they should be removed at the time of examination. Most polyps can be burnt off (Polypectomy) by placing a wire snare around the base and applying an electric current to cut through the base or stalk of the polyp.
An alternative method of examining the large bowel is barium enema. Colonoscopy has the advantage over the barium enema in allowing tissue samples or biopsies to be taken, removal of polyps, and more accurate assessment of your bowel lining
How are you prepared ?
Prior to colonoscopy you will be provided with a preparation kit containing full instructions. For two days before the procedure you will need to follow a low residue diet. You will need to take something to clean out your bowel on the evening before and on the morning of the procedure. You will be given a sedative through a vein in the arm before the procedure to make you sleepy and comfortable. You will have no memory of the procedure. Since sedation is involved, you are advised not to drive a vehicle, operate machinery or make important decisions for at least 12 hours after the procedure.
Special Considerations
As x-ray screening may be used during the procedure, it is essential for female patients that there is no possibility of pregnancy. You must advise the doctor if you have any doubts about this.
You should advise the nursing staff if you have any allergies.
You should cease iron tablets and drugs to stop diarrhoea at least several days before the procedure. The use of blood thinners may also impact on the timing of your procedure, so If you are on these medications, you must discuss the matter with your doctor or contact the gastroenterologist directly. You should also inform your doctor if you have heart valve disease, or have a pacemaker implanted. If you are diabetic ,especially if you need insulin, the gastroenterologist should be advised.
Why do you need a colonoscopy?
Your GP may recommend colonoscopy for a variety of reasons. The most common reason is for colon cancer screening, for example where there may be a family history of colon cancer. Colonoscopy is also performed where there are symptoms of rectal bleeding, abdominal pain, change of bowel habit or a positive faecal occult blood (blood in the faeces/stools.
