Colonoscopy enables your doctor to examine the lining of your colon (large intestine) for abnormalities by inserting a flexible tube as thick as your finger into your anus and slowly advancing it into the rectum and colon. Please ask your doctor about anything you don't understand.
THE PROCEDURE — The colonoscopy will be performed with you lying on your left side. Medications will be administered through the intravenous line. Most endoscopy units administer a combination of a sedative, to help you relax, and a narcotic, to diminish any unpleasant sensations. Many people sleep during the examination and others are very relaxed, comfortable, and generally not very aware of the examination.
The colonoscope is a flexible tube, approximately the size of your index finger. It has a lens and a light source that allows the endoscopist to look into the scope or at a TV monitor. The image on the TV monitor is magnified many times so the endoscopist can see minute changes in tissue.
The endoscope contains channels that allow the endoscopist to obtain biopsies (small pieces of tissue), remove polyps and to introduce or withdraw fluid or air. Neither of these hurt since the lining of the colon does not have that type of pain sensation.
Air is introduced through the scope to open up the colon so that the scope can be moved forward and to allow the endoscopist to see. You may experience a feeling of bloating or gas cramps from the air as it distends the colon. Do not be embarrassed about releasing the air through your rectum if you can. It is important for you to let the doctor know if you are uncomfortable.
What if the colonoscopy shows something abnormal?
If your doctor thinks an area needs further evaluation, he or she might pass an instrument through the colonoscope to obtain a biopsy (a sample of the colon lining) to be analyzed. Biopsies are used to identify many conditions, and your doctor might order one even if he or she doesn't suspect cancer. If colonoscopy is being performed to identify sites of bleeding, your doctor might control the bleeding through the colonoscope by injecting medications or by coagulation (sealing off bleeding vessels with heat treatment). Your doctor might also find polyps during colonoscopy, and he or she will most likely remove them during the examination. These procedures don't usually cause any pain.
What are polyps and why are they removed?
Polyps are abnormal growths in the colon lining that are usually benign (noncancerous). They vary in size from a tiny dot to several inches. Your doctor can't always tell a benign polyp from a malignant (cancerous) polyp by its outer appearance, so he or she might send removed polyps for analysis. Because cancer begins in polyps, removing them is an important means of preventing Colo-rectal cancer.
How are polyps removed?
Your doctor might destroy tiny polyps by fulguration (burning) or by removing them with wire loops called snares or with biopsy instruments. Your doctor might use a technique called "snare polypectomy" to remove larger polyps. That technique involves passing a wire loop through the colonoscope and removing the polyp from the intestinal wall using an electrical current. You should feel no pain during the polypectomy.
What preparation is required?
Your doctor will tell you what dietary restrictions to follow and what cleansing routine to use. In general, the preparation consists of either consuming a large volume of a special cleansing solution or clear liquids and special oral laxatives. The colon must be completely clean for the procedure to be accurate and complete, so be sure to follow your doctor's instructions carefully.
Can I take my current medications?
Most medications can be continued as usual, but some medications can interfere with the preparation or the examination. Inform your doctor about medications you're taking, particularly aspirin products, arthritis medications, anticoagulants (blood thinners), insulin or iron products. Also, be sure to mention allergies you have to medications.
Alert your doctor if you require antibiotics prior to dental procedures, because you might need antibiotics before a colonoscopy as well.
WHAT TO EXPECT IN THE ENDOSCOPY UNIT — Prior to the colonoscopy, a nurse will prepare you for the examination. The nurse will take a history to determine what you already know about the procedure and whether you understand why the examination is being done. Other questions that you should be prepared to answer include:
Have you taken the bowel preparation prescribed to you and followed the clear liquid diet?
Do you have an escort home?
What medications do you take?
Do you have any medical problems, such as heart disease or lung disease?
Do you have allergies to any medications or latex allergies?
Have you had any previous adverse reactions to sedation medications (such as Valium or Versed) or narcotics (such as Demerol, fentanyl, morphine)?
The nurse will start an intravenous line (put a needle in a vein in your arm) to administer medications to help you relax and keep you comfortable during the examination. This is just a pin prick, no worse than having your blood drawn. Your vital signs will be monitored during the examination and for a time after the colonoscopy is over. The nurse will check your blood pressure and pulse either manually or with a machine that continuously monitors your heart rate and rhythm, your oxygen level, and blood pressure. The monitoring machines are not painful. You may also be given oxygen during the examination.
The consent — A doctor will review the examination with you, including possible complications, and will ask you to sign a consent form. He will answer any questions you may have about the examination.
RECOVERY — After the colonoscopy, you will be kept for a time for observation while some of the medicine wears off. The most common discomfort after the examination is a feeling of bloating and gas cramps. You may also be very groggy from the sedation medications or you may have difficulty concentrating. It is usually advised that you not return to work that day. Unless you are given other instructions, you should be able to eat a regular diet after the examination. You should ask your doctor when it is safe to restart aspirin or blood thinning medications.
COMPLICATIONS — Colonoscopy is a safe procedure and complications are rare, but can occur:
Bleeding can occur from biopsies or the removal of polyps, but it is usually minimal and stops quickly or can be controlled.
The colonoscope can cause a tear or hole in the tissue being examined, which is a serious problem, but, fortunately, very uncommon.
Adverse reactions to the medications used to sedate you are possible. The endoscopy team (doctors and nurses) will ask you about previous medication allergies or reactions and about health problems such as heart, lung, kidney, or liver disease. Providing this information to the team ensures a safer examination. You will also be carefully monitored throughout the examination.
The medications can also produce irritation in the vein at the site of the intravenous line. If redness, swelling, or warmth occur, warm to hot wet towels applied to the site may relieve the discomfort. If the discomfort persists, notify your doctor or the endoscopy unit.
The following symptoms should be reported immediately:
Severe abdominal pain (not just gas cramps)
A firm, distended abdomen
Bleeding greater than a few tablespoons.
AFTER COLONOSCOPY — Although patients worry about discomforts of the examination, most people tolerate it very well and feel fine afterwards. Some fatigue after the examination is common. You should plan to take it easy and relax the rest of the day.
You should contact your doctor about the results of your test if you have any questions and especially if biopsies were taken. The endoscopy team can give you some guidelines as to when your doctor should have all the results and whether further treatment will be necessary. Most patients who had polyps removed will require a repeat colonoscopy within three to five years.