The colon, or large intestine, is the last portion of your digestive or gastrointestinal (GI) tract. It starts at the cecum, which attaches to the end of the small intestine. The colon consists of a hollow tube about five feet long that:
- Absorbs water and minerals from digested food.
- Contains the rectum, which stores undigested solid waste.
Cancer of the colon and rectum — called colorectal cancer (CRC) — occurs when a growth on the lining of the colon or rectum has become malignant, or cancerous. Colorectal cancer can be cured, especially when detected early.
The term "colonoscopy" refers to a medical procedure during which a long flexible tube is used to look inside the colon. It is a procedure performed by a gastroenterologist, a well-trained specialist.
The main instrument that is used to look inside the colon is the colonoscope. The colonoscope is a long, thin, flexible tube with a tiny video camera and a light on the end. By adjusting the various controls on the colonoscope, the gastroenterologist can carefully guide the instrument in any direction to look at the inside of the colon. The high-quality picture from the colonoscope is shown on a TV monitor, and gives a clear, detailed view.
Uses of Colonoscopy
Colonoscopy is an important way to check for colon cancer and to treat colon polyps. Polyps are abnormal growths on the inside lining of the intestine; they vary in size and shape and while most polyps are not cancerous, some may turn into cancer. However, it is not possible to tell just by looking at a polyp if it is malignant or potentially malignant. This is why colonoscopies are often used to remove polyps, a technique called a polypectomy.
A Colonoscopy is also a safe and effective way to evaluate problems such as:
- Blood loss.
- Abdominal or rectal pain.
- Changes in bowel habits, such as chronic diarrhea.
- Abnormalities that may have first been detected by other studies, such as an inflamed colon noted on a CT scan of the abdomen.
- Active bleeding from the large bowel.
Another advantage of the procedure is that, when needed, other instruments can be passed through the colonoscope. These may be used, for example, to painlessly remove a suspicious-looking growth or to biopsy, that is, take a small piece of tissue for further analysis. In this way, a colonoscopy may help to avoid surgery or to better define what type of surgery may need to be done.
A shorter version of the colonoscope is called a sigmoidoscope. This instrument is used to screen for problems in the lower part of the large bowel (colon) only. The colonoscope, however, is long enough to inspect all of the large bowel and even the lower part of the small intestine.
Before the Procedure
Regardless of the reason a colonoscopy has been recommended for you, there are important steps that you can take to best prepare for and participate in the procedure.
Talk to Your Doctor
Give your doctor a complete list of all the medicines you are taking including over-the-counter medications and natural supplements and any allergies you have to drugs or other substances. Your medical team will also want to know if you have heart, lung or other medical conditions that may need special attention before, during or after the colonoscopy. It is especially important to discuss the taking of diabetic medications and anticoagulants (sometimes called blood thinners) with your physician before the test.
Prepare Your Colon for the Test
You will be given instructions in advance that will outline what you should and should not do in preparation for colonoscopy; be sure to read and follow these instructions. One very critical step is to thoroughly clean out the colon, which, for many patients, can be the most trying part of the entire exam. It is essential that you complete this step carefully, because how well the bowel is emptied will help determine how well your doctor can examine it during colonoscopy.
Various methods can be used to help cleanse the bowel, and your doctor will recommend what he or she prefers in your specific case. Often, a liquid preparation designed to stimulate bowel movements is given by mouth. Additional approaches include special diets, such as clear fluids, or the use of enemas or suppositories. Whichever method or combination of methods is recommended for you, be sure to follow instructions as directed.
Check your instructions about what to eat or drink the night before your colonoscopy and when to stop eating. Consult your doctor prior to the procedure to determine if the medications you are on should be taken or not prior to the colonoscopy.
Colonoscopies can be done in a hospital, special outpatient surgical center or a physician’s office. You will be asked to sign a form which verifies that you consent to having the procedure and that you understand what is involved. If there is anything you do not understand, ask for more information.
During the Colonoscopy
During the procedure, everything will be done to ensure that you will be as comfortable as possible. An intravenous line, or IV, will be placed to give you medication to make you relaxed and drowsy. The drug may enable you to remain awake and cooperative while preventing you from remembering much of the experience.
Once you are fully relaxed, your doctor will first do a rectal exam with a gloved, lubricated finger; then the lubricated colonoscope will be gently inserted.
As the scope is slowly and carefully passed, you may feel as if you need to move your bowels, and because air is introduced to help advance the scope, you may feel some cramping or fullness. Generally, however, there is little or no discomfort.
The time needed for a colonoscopy will vary, depending in part on what is found and what is done. Afterwards, you will be cared for in a recovery area until most of the effects of the medication have worn off. At this time, your doctor will inform you about the results of your colonoscopy and provide any additional information you need to know. You will also be given instructions regarding how soon you can eat and drink, plus other guidelines for resuming your normal routine.
Although a colonoscopy is a safe procedure, complications can occur, including perforation or puncture of the colon walls, which could require surgical repair. Complications during a colonoscopy are rare. You should also be aware that a colonoscopy is not perfect and even with a skilled physician, some colon lesions (abnormalities) might be missed.
When polyp removal or biopsy is performed, hemorrhage — heavy bleeding — may result and sometimes require blood transfusion or reinsertion of the colonoscope to control the bleeding. Be sure to discuss any specific concerns you may have about the procedure with your doctor.
After the Colonoscopy
Plan to rest for the remainder of the day after your colonoscopy. This means not driving, so you will need to arrange to have a family member or friend take you home.
Occasionally, minor problems may persist, such as bloating, gas or mild cramping, which should disappear in 24 hours or less.
A day or so after you are home, you might speak with a member of the colonoscopy team for follow-up, or you may have questions you want to ask the doctor directly.