Colorectal cancer is the second leading cause of cancer death in the United States. It affects both men and women and almost always starts as a benign growth called a polyp. Polyps originate in the inner lining of the colon where they may be visible during the common screening test known as colonoscopy. Researchers are unsure what causes polyps. Risk factors include a family history of polyps or colon cancer, previous personal history of colon polyps and having ovarian or uterine cancer before the age of 50. Other factors that may contribute to the growth of colonic polyps include individuals with inflammatory bowel disease, smoking, obesity, drinking alcohol, lack of exercise and eating a diet rich in fats.
A colonoscopy is an exam of the inside of the entire large intestine (colon) using a flexible fiber optic instrument called a colonoscope. The colonoscope is about the diameter of your index finger and contains a fiber optic bundle through which light can be passed from an outside source to illuminate the inside of the colon. The colonoscope contains an instrument channel through which biopsy forceps and polyp snares can be passed in order to perform diagnostic and therapeutic procedures within the colon.
Most colon cancers originate from small, precancerous (benign) polyps. Some polyps may grow into malignant colon cancers over time if they are not removed. Since the polyps typically cause no pain or symptoms, the best defense is to find them before they become cancerous and remove them, thus eliminating the chance they may become cancerous. When discovered early, colon cancer is highly treatable, so colonoscopy screening is crucial.
Individuals with average risk should start getting screened for colon cancer at age 45. Most guidelines do not recommend screening for asymptomatic individuals under the age of 45 unless they have a positive family history or a predisposing, inherited syndrome.
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Once you schedule your colonoscopy, it’s important to prepare and understand the procedure. Here’s what to expect:
Bowel preparation for colonoscopy refers to the laxatives taken before the procedure to clean the colon of fecal debris. Your doctor will give you instructions to prepare for the procedure. Proper bowel preparation is very important and can affect the accuracy of your results. Any fecal debris left in the colon could obscure identification of a polyp or even a small cancer. Several studies have shown that fewer small and large polyps are detected in patients with less-than optimal bowel preparation. Poor preparation has several potential consequences during the procedure as well. First, your colonoscopy may take longer because the doctor will need to clear out debris. Second, your doctor may lack confidence that the colon lining was seen adequately and ask you to return for a subsequent screening sooner than would be otherwise recommended, such as one year, rather than five or 10. Finally, if the preparation is very poor, the doctor may have to stop the procedure entirely and ask you to reschedule. Be sure to read the instructions provided by your gastroenterologist carefully to ensure proper preparation for your exam. Ask if the doctor recommends split dosing. Split dosing refers to taking half the laxative dose the night before colonoscopy, and the other half on the day of the procedure, usually about four to five hours before the procedure is scheduled. Several studies have shown that split dosing significantly improves the quality of the preparation for colonoscopy.
Certain medications, specifically blood thinners, will likely need to be temporarily stopped prior to the colonoscopy to minimize the risk of procedure complications. The management of these drugs should be handled either by the doctor who prescribed them or the doctor doing the colonoscopy, or by both in consultation. You should not decide to stop these medicines on your own.
During the procedure
An intravenous line will be started in your arm to give you the necessary sedative medication to make you relaxed and sleepy before the procedure starts. The examination is performed while you are lying on your side. The rectal area and the colonoscope will be coated with a lubricating jelly, then the colonoscope will be guided into the rectum and gently advanced through the colon. Movement of the colonoscope may cause mild cramping. Air is put into the colon to gently distend it. This may cause a mild feeling of fullness. Do not be concerned if you feel you have the urge to have a bowel movement, as this is due to the air distending the colon. Your colon will be free of waste material, as a result of the laxative preparation.
Colonoscopy is a very safe procedure for almost any patient, regardless of age or other medical conditions. While complications are possible, they are rare. Complication risks include the following:
- Colon perforation or bleeding that could require hospitalization, transfusion or surgery – risks are slightly greater if a large polyp is removed.
- Medication reactions and vein inflammation at the site of the intravenous line.
- Drop in blood pressure or slow breathing due to procedure or sedative medications.
- Death – extremely rare, but remains a remote possibility.
Be sure to tell your gastroenterologist before the procedure if you have a history of drug reactions or allergies. Women should notify us if they are or think they might be pregnant.
After the procedure
The colonoscopy usually takes 20-30 minutes. Following the procedure, you will be observed until you are alert enough to leave with a friend or relative. We will discuss the results of the procedure and give you instructions for post-colonoscopy care before you leave. You should not plan to drive or participate in strenuous activity for the rest of the day. You will be able to eat lightly when you go home. We will contact you when biopsy results are available.