Colonoscopy
What is a colonoscopy?
A colonoscopy is a procedure used to examine the large bowel, which also allows a variety of operations to be carried out through the instrument. Such operations will include taking tissue samples (biopsies), the removal of polyps, dilatation of narrowing’s and various treatments to arrest certain forms of bowel haemorrhage.How are you prepared?
Prior to colonoscopy examination, you will be provided with a preparation kit containing full instructions. For a few days before the procedure you will need to follow a low residue diet. The night before the examination you will need to take laxatives and either on the evening before the examination or on the morning of the examination, you will need to take further preparation, frequently a quantity of salty tasting solution, which completely flushes out the colon.You will be given a sedative before the procedure begins and usually you will not remember anything about the actual examination.
What do we do?
The colonoscopy is a long and highly flexible tube about the thickness of the index finger. It is inserted through the rectum into the large bowel and allows inspection of the whole of the large bowel.Occasionally narrowing’s in the bowel or other diseases may prevent the instrument being inserted through the full length of the colon.
As cancer of the large bowel arises in pre-existing polyps, it is advised that if polyps are found at the time of the examination they should be removed. Placing a wire snare around the base and applying an electric current, thus preventing any further change to cancer, can burn off most polyps.
Alternative Treatments:
One alternative method of examining the large bowel is a barium enema. A variety of studies have shown that this is both less accurate and additionally does not allow specific treatments, such as removal of polyps, to be undertaken.
Virtual colonoscopy is a technique where either CT scanning or Magnetic Resonance is used to develop images which are then computer reconstructed into a three dimensional model. This is an exciting technique, which may, in the future, be a useful alternative to colonoscopy. Currently, the technique is not considered sufficiently accurate to replace colonoscopy. Biopsies or removal of polyps cannot be undertaken with this technique. Therefore the result is inconclusive; if polyps are found or biopsies are required, the colonoscopy will have to be performed.
Special Considerations:
- AS AN X-RAY SCREEN MAY BE USED DURING THE PROCEDURE IT IS ESSENTIAL FOR FEMALE PATIENTS THAT THERE IS NO POSSIBILITY OF PREGNANCY. YOU MUST ADVISE THE NURSING STAFF IF YOU HAVE ANY DOUBTS ABOUT THIS.
- You should advise the nursing staff if you are sensitive (allergic) to any drug or other substance.
- There are some medical conditions which it is essential that your colonoscopist is aware of:
- Insulin dependant diabetes – this may require in-hospital preparation
- Heart valve disease – this will usually require antibiotic cover
- Blood thinning medications
- Aspirin poses minimal, if any, increased risk. If you are taking aspirin simply as a lifestyle measure, then it should be ceased one week before the procedure. If you are taking it for a medical indication (e.g. transient ischaemic attacks, previous strokes, heart disease, etc) then you should continue on the drug.
- Anti-coagulants – COUDADIN, MAREVAN (Warfarin), CLEXANE, DINDEVAN
- Anti-thrombotic agents – these include: AGGRASTAT, ARIXTRA, ASASANTIN, ISCOVER, PERSANTIN, PLAVIX, REOPRO, THROMBOTROL, TICLID, TILODENE. Removal of polyps while on any of these blood-thinning agents may result in serious haemorrhage. This is a complex problem where the risks of ceasing blood-thinning medication must be balanced against the risks of post-polypectomy haemorrhage.
- Recent joint replacement, coronary stent insertion, pacemaker insertion – may require anti-biotic cover.
- You should cease iron tablets and drugs to stop diarrhoea at least several days before the procedure.
- It is preferable that you are not taking aspirin or non- steroidal anti-inflammatory drugs.
How accurate is colonoscopy?
Few investigations in medicine are perfect. Colonoscopy has shown to be significantly more accurate than barium enema in the detection of bowel polyps and cancers. A number of recent studies have examined the accuracy of colonoscopy and concluded that where the instrument cannot be passed all the way around the colon, there is a significant risk of missing polyps and cancers in the unexamined portion of the bowel. For this reason, if your Colonoscopist is unable to pass the instrument the entire length of the colon, you may need a barium enema. With complete colonoscopy up to 3% of bowel cancers can be missed. The risk appears to be smaller for highly trained Colonoscopists. Small benign polyps can be missed in up to 6% of cases.Safety and Risks:
YOU MUST READ THIS SECTION CAREFULLY. This is important information about potential complications. It is not our intention to frighten or dissuade you from having the investigation, but we must outline the risks. With this knowledge, you may either elect to accept the risks and go ahead with the procedure, or decide not to have it. Depending on the reason for the procedure, there may be risks of not having the procedure, e.g. missed disease or delayed diagnosis. These risks may be fatal, e.g. delayed diagnosis of cancer.
For inspection of the large bowel alone (diagnostic colonoscopy without removal of polyps or other operative measures) complications of colonoscopy are uncommon. Most surveys report complications in less than 1 in 1000 examinations. Complications, which can occur, include intolerance of the bowel preparation solution or reactions to sedatives used. Major complications such as perforation of the bowel, bowel haemorrhage, injury to the spleen or other internal organs is extremely rare, but if they do occur, may require surgery.
When operations such as the removal of polyps are carried out, there is slightly higher risk of perforation or bleeding from the site where the polyp has been removed.
Complications of sedation are uncommon and are usually avoided by administering oxygen and monitoring the electrocardiograph. Rarely however, particularly in patients with severe cardiac or chest disease, serious sedation reactions can occur.
A NUMBER OF RARE SIDE EFFECTS CAN OCCUR WITH ANY MEDICAL PROCEDURE. IF YOU WISH TO HAVE FULL DETAILS OF RARE COMPLICATIONS, YOU SHOULD INDICATE THIS TO YOUR DOCTOR BEFORE THE PROCEDURE, STRESSING THAT YOU WISH FOR THE POSSIBLE COMPLICATIONS TO BE DISCUSSED.
Antibiotic Cover
Pressure on mucosal surfaces can result in bacteria passing into the blood stream. This can occur even with vigorous teeth cleaning and is generally of no significance. However, if heart valves are damaged or there are metal or plastic indwelling devices (e.g. pacemakers, artificial joints) bacteria could possibly lodge on these surfaces and cause serious infection. Antibiotic cover is not required for a simple endoscopy. Colonoscopy or complicated upper endoscopy (e.g. oesophageal dilatation) may need to be performed under antibiotic cover in the presence of congenital heart disease, damaged heart valves, heart valve replacement, joint replacement, or coronary stent placement within the last six months, recent pacemaker insertion. IF YOU HAVE ANY OF THESE CONDITIONS OR HAVE BEEN ADVISED BY A CARDIOLOGIST OR OTHER SPECIALIST TO HAVE ANTIBIOTIC COVER FOR MEDICAL PROCEDURES, YOU MUST INFORM THE COLONOSCOPIST. Depending on the particular condition, antibiotic cover is usually given as a single intravenous dose, one or two antibiotics at the beginning of the procedure.Removal of Polyps:
The majority of bowel cancers arise from benign adenomatous polyps. Some polyps never become cancerous. It is impossible to predict which polyps will progress to cancers and which will remain as benign polyps. For this reason it is advised that all polyps be removed at the time of examination, as you will be sedated. Therefore if you agree to have removed any polyps found during the procedure, please sign the form below. If you have any queries or reservations about removing polyps, please inform the staff before the procedure. In the unlikely event a haemorrhage occurs after removing a polyp, a blood transfusion or operation may be necessary.
After your colonoscopy:
The sedative/painkiller you are given before the procedure is very effective in reducing any discomfort. However, it may also affect your memory for some time afterwards. Even when the sedative appears to have worn off, you may find you are unable to recall details of your discussion with the doctor. If you do not recall discussions following the procedure, you should contact your doctor.
For straightforward diagnostic procedures you can return to normal food intake as soon as your sedation has worn off. You should, however, be careful to avoid alcohol over the next 12 hours as traces of sedation remaining in your bloodstream may combine with alcohol to produce a far more intoxicating effect than normal.
During the procedure it is necessary to fill the colon with air to ensure that all areas of the bowel are examined. Not all the air can be removed at the end of the procedure and you are likely to feel some windy discomforts for a few hours afterwards.
If you have any severe abdominal pain, rectal bleeding, fever or other symptoms, which cause you serious concern, then you should contact your doctor immediately.
Discharge Information:
As stated previously, the immediate effects of the sedation wear off quite quickly, however, the drugs stay in your system for approximately 12 hours. During this time your judgment and coordination may be impaired.Please be aware of the following during that time:
- You must have a responsible adult come to the Endoscopy Unit to pick you up, drive you home and stay with you for no less than 12 hours following your procedure.
- You may resume your normal diet.
- Your referring doctor will receive a full report from the Specialist
- Do not drive for 12 hours post procedure. It is illegal to drive whilst under the influence of a drug
- No cooking tea, or using any electrical appliances or tools (such as sharp knives
- Do not travel unaccompanied on public transport or go out by yourself
- Do not resume work until the following day
- Do not sign any legal documents until the next day.