A colonoscopy is a medical procedure that allows a doctor to look inside the large intestine (colon and rectum) for ulcers, inflammation and abnormal growths. Most colon cancers begin as benign growths, called polyps, that later turn cancerous. According to the American Cancer Society, colorectal cancer cases have decreased significantly over the past 15 years, partly because of early detection and removal of precancerous polyps found during colonoscopy.
Most doctors recommend that patients at average risk of colon cancer schedule their first colonoscopy at age 50. The results of the test determine the recommended follow-up. If results are normal, a second colonoscopy is usually recommended in 5 to 10 years.
A 2008 study in the New England Journal of Medicine confirms that cancer of the colon develops slowly enough that testing every five years is sufficient, unless a previous colonoscopy has given reason for increased vigilance.
Patients at higher risk for colon cancer should have their first colonoscopy before age 50 and will need more frequent follow-up tests. Your doctor’s recommendations will be based on previous colonoscopy results and your medical history. The American Cancer Society provides excellent guidelines for screening, surveillance and early detection of colorectal adenomas and cancer in people at increased risk.
People older than 50 account for 90 percent of colorectal cancer diagnoses. Other risk factors include a history of inflammatory bowel disease, including Crohn’s disease and ulcerative colitis; personal history of colorectal cancer or specific types of polyps; and family history of colorectal cancer or known genetic predispositions.
Lifestyle factors including smoking, dietary choices and lack of exercise also increase your risks. African-Americans and Ashkenazi Jews have a greater incidence than the average population.
Preparation for Colonoscopy
A colonoscopy requires a completely empty bowel to ensure that the surgeon or gastroenterologist can clearly see the entire intestine. Buy laxatives at the pharmacy, as indicated by your doctor’s preparation instructions. Your doctor will probably put you on a clear liquid diet the day before the procedure. The afternoon or evening before, you will take the laxatives. Stay near a bathroom.
Most patients are sedated enough to sleep through the procedure. They usually don't remember it. Some patients receive only light sedation or pain medicine and stay awake throughout. The doctor inserts a thin flexible tube called a colonoscope, or scope, into the rectum and colon. The scope has a light and fiber optics that allow him to see images on a video screen during the procedure.
A colonoscopy is performed as an outpatient procedure. After the sedation has worn off, you will be allowed to go home. You will not be allowed to drive until the following day. A friend or family member must take you home from the clinic or office. Most people return to work the next day.