Doctors perform colonoscopies to evaluate the large intestine, or colon. Using a long, flexible tube about as big in diameter as your pinky finger, a doctor can look inside the colon. This tube has a fiber optic video camera as well as a bright light so the physician can inspect the inside of the colon. The scope also has a channel through which instruments can be placed to take biopsies or remove polyps. Colonoscopies are most commonly performed as a screening for colon cancer, but they can also be used to evaluate symptoms such as diarrhea, rectal bleeding, anemia, or weight loss.
What is a colonoscopy?
A colonoscope is a long, slender, flexible tube coated with plastic. Using cables inside the scope, the physician can turn the tip of the scope almost a full 360 degrees in every direction. While the scope is gently inserted, the endoscopist can direct the scope carefully around several corners to reach the far end of the large intestine called the cecum. Most doctors who have been trained to perform this exam can reach the cecum in 99% of cases.
What is the colon?
Five feet in length, the large intestine is the last segment of the digestive tract. The colon, or large intestine, is a muscular tube with a wall that is just a few millimeters thick. Travelling from the mouth to the anus, food passes through the esophagus to the stomach. After being churned in the stomach, it passes into the small intestine where nutrient absorption occurs. The unabsorbed food and liquid then pass into the first part of the colon, the cecum. The colon stores this liquid material where water is reabsorbed to form solid stool. Essentially, the large intestine is a storage area where water is reabsorbed. The remaining material is solid stool which is then passed from the rectum by way of the anus.
What is the preparation for a colonoscopy?
Preparation for a colonoscopy is very important. In order to adequately visualize the colon and clear it of polyps, it must be cleansed. If a patient wants to get the longest interval possible between procedures, then a well-prepared colon is essential.
First, drink only clear liquids the day before. No solid food or seeds whatsoever. Clear liquids include water, beef or chicken broth, clear apple juice, white cranberry or white grape juice, clear soda (7UP, ginger ale), Gatorade, Crystal Lite, lemon ice, Popsicles and JELL-O (any color but red).
Then you will drink a colon-cleansing preparation such as PEG following two laxative pills. The preparation varies somewhat, but it is important to consume the entire mixture to achieve the best results. Failure to do so could result in having to repeat the exam in just a few weeks.
Click one of the links below to get further instructions specific to your procedure. This information can also be found on this page under "Prep Instructions".
- Prep Instructions - Morning Procedures
- Prep Instructions - Afternoon Procedures
- Prep Instructions - Constipation
Should you stop any of your medications before your colonoscopy?
Patients should tell their doctors about all health conditions they have especially heart and lung problems, diabetes and allergies. Patients should also bring a complete list of all medications they are taking. Your doctor may ask you to temporarily stop taking medications that affect blood clotting.
Medications that may be restricted before and after upper GI endoscopy include: some dietary supplements, diabetes medications, blood thinners, and nonsteroidal anti-inflammatory drugs like aspirin, ibuprofen (Advil, Motrin), naproxen (Aleve, Naprosyn) and prescription anti-inflammatories.
What is the procedure?
After checking in at the appropriate time on your instructions, you will be asked a series of questions. Afterwards an intravenous catheter will be placed in your arm. You will then be wheeled on a gurney into the exam room. Once your vital signs have been established, medication will be given to sedate you. Usually you will be given a sedative called Versed which is in the same class as Valium. You may also be given a pain medication, either Demerol or Fentanyl. This mixture provides a light sedation, helping you relax and become comfortable.
Once you are very comfortable, the doctor gently inserts the colonoscope through the anus all the way to the cecum. The fiberoptic image is transmitted to a screen the physician watches while he moves the scope. After identifying the landmarks of the cecum, the scope is slowly withdrawn inspecting all portions of the colon. Air is passed through the scope to inflate the colon so as to see around all the folds.
Removal of polyps and biopsy
While the scope is being withdrawn, polyps are removed when they are found. Your doctor will use thin instruments through a channel in the scope to separate and then remove any polyps that are identified. Since most cancers begin as a benign polyp, removing them has been found to prevent colon cancer.
Should inflammation be seen or suspected, your doctor can perform simple biopsies of the lining of the colon. Both biopsy and polyp removal are painless.
Our doctors have consistently had a high polyp detection rate that surpasses the national average.
Colonoscopy usually lasts 20-30 minutes. Afterward, you are moved to a recovery area where you are encouraged to pass gas as air was inserted into your colon during the procedure. During this time you may notice some bloating and cramping. The sedation also takes time to wear off. Therefore, you may be in the recovery area for 1-2 hours. Full recovery may take an entire day. You should not operate a motor vehicle or any machinery until the next morning. You must have a ride home from the center.
Should you develop any of the following symptoms afterwards, contact your doctor immediately: severe abdominal pain, fever, bloody bowel movements, dizziness, or weakness.