Massachusetts General Hospital Digestive Healthcare Center physicians use a colonoscopy, the primary and most effective screening technique, to screen patients age 50 to 75 for colorectal cancer.
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A colonoscopy is considered the primary and most effective screening technique to screen patients ages 50 to 75 for colorectal cancer. If you are older than 75, ask your doctor if you should be screened.
A colonoscopy is a safe, private and usually painless procedure that takes about 30 minutes to complete. A colonoscopy may be done in a hospital outpatient department, clinic or in a doctor’s office.
During the procedure, a general surgeon or gastroenterologist (a doctor who specializes in identifying and treating gastrointestinal diseases) uses a colonoscope to see the entire colon. A colonoscope is a long, flexible tube. If a polyp is found, the doctor may remove it during your colonoscopy.
During your colonoscopy, the doctor may use the colonoscope to take a biopsy – a small tissue sample – if anything looks abnormal. The tissue sample will be sent to the lab for further testing.
Preparing for a Colonoscopy
For the test to be effective, the colon and rectum must be empty and clean.
Before the Test
You will take medication to clean out your colon the day before the test and may be prescribed an enema that morning. Your doctor will give you instructions to help you prepare for your colonoscopy. Read the instructions carefully a few days before your colonoscopy since you may need to shop for special supplies and get laxatives from a drug store. If you have any questions, call your doctor's office to review instructions with the nurse.
Many patients find the bowel preparation to be the most unpleasant part of the test. The medication you take to clean out your colon will most likely cause you to be in the bathroom quite a bit. You may be given other instructions, too, such as foods to avoid before the test.
Be sure your doctor is aware of any medications you are taking, as you may need to change how you take them before the test.
During a Colonoscopy
The test usually takes about 30 minutes, but it may take longer if a polyp is found and removed. Before the test begins, you will be given medication through an IV to make you feel comfortable and sleepy. You may be awake, but you will not be aware of what is going on and may not remember the test afterward.
If a small polyp is found, your doctor may remove it. If your doctor sees a larger polyp or tumor or anything else not normal, a biopsy may be done at the same time. To do this, a small tissue sample is taken out through the colonoscope. The tissue is looked at under a microscope to see whether it is a cancerous growth, a benign (non-cancerous) growth or a result of inflammation.
After the Test
Plan to have someone drive you home from the test because the medication used can affect your ability to drive. Some people may experience gas pains or cramping after the test, but most feel fine once the medication wears off completely.
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