What happens during the test?
A colonoscopy is usually performed on an outpatient basis at a hospital. It takes approximately 15 to 45 minutes.
You may be given a pain medication and a sedative to help you relax and to relieve some of the discomfort during the procedure, although, if you prefer, it can be done without sedation.
While you are lying on your left side or on your back, your doctor (a gastroenterologist or another qualified health care professional) will gently insert the colonoscope into your rectum and slowly guide it through your colon until it reaches the beginning of the colon or the last section of the small intestines. The flexibility of the instrument allows your doctor to safely negotiate the many bends of your colon. In many cases, you may be asked to change position to allow the colonoscope to move along the colon more easily and to provide a better view for the doctor.
The colonoscope will blow air into the colon, inflating it so the doctor can see better. The lining of your colon is also examined while the colonoscope is being carefully removed. The camera attached to the end of the colonoscope can also record images that can be studied later.
The test is usually well tolerated, but during the test you may feel mild cramping, bloating, pressure, an urge to have a bowel movement, and gas pains. Slow and deep breathes may help to lessen this discomfort. You may also occasionally pass gas during the test.
How should I prepare for this test?
To perform a colonoscopy safely and effectively, the colon must be empty. Your doctor will give you special instructions on how to do this. In general, starting one to two days before the colonoscopy, you will be required to stop eating solid foods and start a clear liquid diet that does not contain any food coloring but may include:
- coffee
- tea
- water
- clear broth
- gelatin
- ginger ale
- clear juices
You will be required to use a laxative the night before or possibly the day of the test. The type of laxative prescribed varies. Some laxatives involve taking 1 gallon of fluid but if this is not the case, it is important to prevent dehydration by drinking plenty of clear fluids during the diarrhea. In some cases, an enema may be necessary.
Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any medication allergies and medical conditions that you may have.
Also, tell your doctor if you are pregnant or suspect that you might be pregnant.
Ask your doctor or pharmacist whether you need to stop taking any of your medications before the test.
Arrange for someone to drive you home from the hospital.
What can I expect after the test?
You may be asked to stay for observation after the test to allow any medications you have taken to wear off. In addition, you may still feel drowsy and experience cramping and bloating, which is usually relieved by passing gas. You should be able to return to your normal diet after the test, but follow any instruction from your doctor. Drink plenty of liquids to replace the fluids that were lost from using laxatives.
After the test, you should have someone drive you home (or accompany you on public transportation) unless you were not sedated. If you were sedated, you must not drive or operate machinery for 24 hours.
If you notice any of the following after the test, contact your doctor immediately:
- dizziness
- fever
- heavy bleeding from the rectum (a small amount of bleeding is normal)
- severe pain in your abdominal area
Results
The doctor can often discuss the visual results immediately after the test. However, if a biopsy was performed, analysis in the lab may take up to a few weeks.
Interpretation of both the visual results and the tissue samples allows the doctor to provide a diagnosis and recommend possible treatments. In some cases, more tests may be necessary.