(Examination of the large bowel)

  What is Colonoscopy?

A colonoscopy is an internal examination of the colon (large intestine) using an instrument called a colonoscope. The colonoscope is a small camera attached to a flexible tube which is used to examine the entire length of the colon.

 

How is the test performed?
 

You will lie on your side or back as the doctor slowly passes the colonoscope along your large intestine to look at the lining. Your doctor will, again, examine the lining as the colonoscope is taken out. Air will be inserted through the scope to provide a better view. Suction may be used to remove secretions. Tissue samples may be taken with tiny biopsy forceps inserted through the scope. Polyps may be removed with electrocautery snares. Photographs may be taken.

Specialized procedures, such as injection therapy, clipping, and tattooing to better localize lesions may be performed.

 

How to prepare for the test?
 

Thorough cleansing of the bowel prior to colonoscopy is very important so that the procedure can be accurate and complete. You will be given detailed instructions for doing this. A bowel preparation is made up of either drinking a large quantity of a special cleansing drink, or may involve a combination of laxative pills and a clear liquid drink. To avoid dehydration during this preparation phase, you will be asked to drink plenty of clear liquids such as juices and broths. Preparation for colonoscopy can very rarely cause kidney problems.

What about the medications I am taking?
 

You should be able to continue taking your usual medications with some exceptions. Please tell your health care provider what you are taking and particularly if you are taking:

Aspirin products
Arthritis drugs
Plavix
Blood thinners such as Coumadin/Warfarin
Insulin
Diabetes pills
Iron supplements

Since your health care provider may ask you to stop or change the doses of these medicines before the procedure.

Please also tell your health care provider if you have:
- a joint replacement
- a heart valve replacement
Since antibiotics may be needed before the procedure.


 How will the test feel?
 

Just before the procedure, you will be given a sedation medication and a pain killer by vein. This will produce relaxation and a drowsy feeling. You may feel pressure as the scope moves inside. Brief cramping and gas pains may be felt as air is inserted or as the scope is advanced. The passing of gas is expected and necessary. After the exam there may be abdominal cramping and considerable passing of gas may occur. Because of the sedation, you may have no memory of the test. Sedation should typically wear off in a few hours.


WHAT IF THE DOCTOR FINDS SOMETHING WRONG?

 
Your doctor may pass an instrument called a biopsy forceps through the colonoscope and take a small piece of bowel lining to look at under the microscope. If colonoscopy is being done to find bleeding sites, your doctor may stop the bleeding through the colonoscopy by:
- injecting drugs
- sealing off bleeding vessels with heat treatment or other methods such as small clips or liquid injection.

Your doctor may also find polyps which will most likely be removed or biopsied during the procedure.

 

What are polyps and why are they removed?
 

Polyps are growths in the bowel lining and they can be as small as a tiny dot or up to several centimeters big. They are not usually cancer but can grow into cancer over time. The doctor usually removes a polyp through the colonoscope using a wire loop or snare to separate the polyp from the bowel wall. An electric current is sometimes used.


What are the risks of colonoscopy?
 

(a) Bowel perforation – the bowel wall may be punctured. This can cause leakage of bowel contents into the abdominal cavity. The risk is approximately 1 to 2 per 1000 tests but may be higher when polyps are removed, particularly with large polyps. This is treated by keeping the bowel empty using suction and a tube passed into the stomach or bowel via the nose. Fluids and antibiotics are given via an intravenous drip. This will require a hospital stay. A surgical repair operation requiring a longer hospital stay may be needed.

(b) Heavy or persistent bleeding from biopsy or polyp – removal sites. This may be immediate or may be delayed by as much as two weeks. The bleeding may stop on its own or may require additional therapies through the colonoscope. Very rarely, surgery may be needed to stop bleeding which cannot be stopped via these means. Very rarely, a blood transfusion may be needed if there is a lot of bleeding.

(c) Having a normal colonoscopy does not guarantee that you do not have or will not get colon cancer. Polyps or cancer can be missed. This risk is higher if your bowel is not cleaned properly. It is very important that you follow the instructions to clear your bowel before the procedure.

(d) Adverse reaction to sedative medication causing breathing problems or low blood pressure is very rare. Also very rarely, heart and lung problems can occur such as low oxygen levels and lowered blood pressure. People with underlying ill health are more at risk.

(e) Nausea, vomiting, bloating or rectal irritation can occur during the preparation phase from medications that cleanse the bowel. If nausea, vomiting or bloating occurs, stop the preparation for 1 to 2 hours and then begin again very slowly, if possible, until the bowel is cleansed thoroughly.

(f) Death due to complications of colonoscopy is extremely rare.

  What if I do not have the procedure?
 

A serious colon problem can be missed such as a polyp, tumor, or inflammation of the bowel.


  Are there other tests I could have instead?
 

There are a number of other tests that could be done such as flexible sigmoidoscopy, double contrast barium enema, virtual colonoscopy utilizing a CT Scan, and stool tests to detect hidden blood and to look for abnormal DNA.

Video

Colonoscopy Video