Colonoscopy enables your physician to examine the lining of the colon for abnormalities. While the patient is under mild sedation, the physician inserts a flexible fiberoptic instrument called a colonoscope into the rectum and advances it through the colon (large bowel). Cancer can occur anywhere from the end of the colon (rectum) to the beginning of the colon, which is called the cecum. The colonoscope examines this entire area. Polyps and even small tumors can be removed painlessly at the time of a colonoscopy so it is really a "therapeutic," not just a "diagnostic" test.
Colonoscopy allows examination of the entire colon. Sigmoidoscopy is done with a shorter endoscope and only examines the left side of the colon. Only about 50% of polyps are found in the left side of the colon within reach of the sigmoidoscope. Sigmoidoscopy is generally performed without sedation and may have a more limited preparation.
In patients with no gastrointestinal problems and no risk factors for colon cancer, the American Cancer Society recommends a first screening colonoscopy at age 50.
However, if you have bowel symptoms such as blood in your stool or a significant change in your bowel movements or their frequency, you should see a doctor right away. If you have any risk factors for colon cancer such as Crohn's disease, ulcerative colitis or a family history of colon cancer, your doctor may want to order the colonoscopy long before you turn 50. If a member of your immediate family, such as a sibling or a parent has had colon cancer, you should begin screening at least 10 years before the age your relative was when diagnosed. The frequency of colonoscopy is determined based on your risk factors and whether or not you have polyps on your colonoscopy. In the average risk patient with a normal colonoscopy the test is repeated every 5-10 years.
Alternatives to colonoscopy include other tests that examine the whole colon such as barium enema or CT colonography (virtual colonoscopy). Less frequently used are the fecal occult blood test cards and sigmoidoscopy. With this method, yearly tests are done to screen your stool for blood. If these tests are negative, a flexible sigmoidoscopy is done every 3-5 years. If the stool blood tests are positive or there are polyps on sigmoidoscopy, a full colon examination is necessary.
The colon must be completely clean for the procedure to be accurate and complete. The colon is prepared by drinking of a bowel preparation which will be prescribed by your doctor. Most commonly, the preparation consists of drinking a large amount of non absorbable liquid that irrigates the colon. (e.g. Golytely, Nulytely). If you find the taste to be unpleasant, sucking on an orange or a lemon after each drink can be helpful. If you prefer to refrigerate the drink, do not refrigerate the entire amount because if the liquid is too cold, it can dangerously decrease your body temperature. Your physician will give you instructions for the particular prep you will take. If you have questions or difficulties, you should contact your doctor's office.
Although most medications can be continued as usual, some medications such as arthritis medications, anticoagulants, insulin, and iron products may need to be modified. It is therefore important that you inform your physician of all medications you are currently taking, including vitamin supplements. It is also important to inform your physician of any allergies to medications at least 1 week prior to the procedure. Generally, medications such as Coumadin® (warfarin), aspirin, Plavix®, ibuprofen and several vitamin supplements may increase your risk of bleeding and you must discuss these with your doctor.
If you have diabetes, your medications need to be changed during the time of the preparation and the day of the procedure and you should speak to your primary care physician regarding this.
If you have a pacemaker, make sure your doctor is aware of this as some procedures during colonoscopy require use of a small amount of electricity that may interfere with it.
Except under unusual circumstances, colonoscopy is conducted on an outpatient basis in our endoscopy suite. You will receive instructions from your doctor's office regarding the time your test is scheduled and what time you should arrive at the hospital. Since you will receive intravenous sedation for the procedure, please have a family member or a friend meet you at the hospital after your test to assist you in returning home.
Colonoscopy is usually well tolerated with minimal discomfort. There is often a feeling of pressure, bloating, or cramping at times during the procedure, which is related to the air that is put in the colon during the exam. The doctor gives you intravenous sedation to help you relax and tolerate any discomfort during the procedure. While you are in a comfortable position on your side or on your back, the colonoscope is advanced through the large intestine. As the colonoscope is withdrawn, the lining is carefully examined. The procedure usually takes about 20 minutes to perform.
If your doctor thinks an area of the bowel needs to be evaluated in greater detail, a forceps instrument is passed through the colonoscope to obtain a biopsy. This specimen is submitted to the pathology laboratory for analysis. Biopsies are taken for many reasons, and not necessarily because cancer is suspected. If the colonoscopy is being performed to identify sites of bleeding, the areas of bleeding may be controlled through the colonoscope by injecting certain medications or by sealing off bleeding vessels with heat treatment. If polyps are found, they are generally removed if safe. Generally, these procedures are not painful.
Polyps are abnormal growths from the lining of the colon which vary in size from a tiny dot to several inches. The majority of polyps are benign, but it can be difficult to discern whether a polyp is benign or cancerous by its outer appearance alone. Therefore, polyps are removed and analyzed microscopically. Removal of colon polyps is an important means of preventing colon cancer as the majority of cancers develop from polyps.
Tiny polyps may be completely destroyed by biopsy. Larger polyps are removed by a technique called snare polypectomy, in which a wire loop is passed through the colonoscope and the polyps are cut from the intestinal wall by means of a small electrical current.
If the colonoscopy reveals cancer, when the biopsy results return, you will have a surgical consultation. The majority of colon cancers require surgery, which is frequently performed laparoscopically. Any additional testing that is required will be discussed with you during the consultation.
After the test, you will be monitored in the recovery room until most of the effects of the medication have worn off. You may feel some cramping or bloating because of the air introduced into the colon during the examination. This should disappear quickly with the passage of gas.
Generally, you should be able to eat normally after the colonoscopy. If your doctor recommends diet modifications, you will be instructed regarding this. If you feel nauseous or are having persistent pain, you should inform the recovery room nurse or call your doctor. If you feel the onset of nausea when you start to eat, it is best to stop eating; usually the nausea will pass and you will be able to resume eating several hours later. Sometimes this nausea or upset stomach is due to the medications given during the colonoscopy.
It will take about one week to receive the results of your biopsy. If you have not received the results from your doctor's office after 1 week, contact your physician.
You should not drive a vehicle or perform strenuous activities on the afternoon or evening following colonoscopy. Unless you have had a polypectomy, you should be able to resume all normal activities the day after your colonoscopy. If you have any doubts about resuming an activity, call your doctor.
You should resume your usual medications on the evening following your colonoscopy. It is especially important that you resume taking your cardiac and blood pressure medications. However, if you have diabetes and are taking insulin, do not resume your full insulin dose until you are tolerating a regular diet. If you have any questions regarding your insulin dosage, please call your internist or general practitioner. Unless prescribed by a physician, avoid aspirin, Motrin®, Advil® or similar analgesics for 2 to 3 days. In general, when you resume your diet you should also resume your prescribed medications. For other blood thinners such as Plavix® and Coumadin®, your physician should give you specific instructions.
Colonoscopy is generally a very safe procedure. However, in rare circumstances, complications can occur. If you develop any of the symptoms below, call your doctor.
Abdominal pain — a small amount of abdominal discomfort following the test is normal. If you have a small amount of stomach upset, 1 tablespoon of Mylanta® or Maalox® may be very helpful. However, if you have persistent abdominal pain, or find that your abdominal discomfort is getting worse either the day of the test or several days thereafter, it is important that you contact your doctor.
Bleeding — A small amount of rectal bleeding after the colonoscopy is normal. However, if your rectal bleeding is severe (more than one half cup), contact your doctor.
Fever — If you develop a fever above 100.4 in the 2 to 3 days following your colonoscopy, contact your doctor.