Jefferson University Hospitals

Frequently Asked Questions

What is colonoscopy?

Food passes through the stomach and is digested in the small intestine. Here, nutrients are absorbed, then waste enters the colon, also known as the large intestine. The colon absorbs excess fluid and the final result is a formed bowel movement, which leaves through the anus.

Colonoscopy is an examination of the lining of the colon to look for abnormal growths called polyps, inflammation, bleeding sites or ulcers. It is used to understand why patients have symptoms such as abdominal pain, blood in the stool, weight loss or a change in bowel habits. The procedure is also performed to detect polyps and cancer in patients without symptoms. Most often, colon polyps do not cause symptoms, and this is why screening is recommended.

Colonoscopy is diagnostic and can be therapeutic. That is, if a polyp is found, it can be removed during the exam and sent to the lab to see if it contains cancer cells. Most polyps are benign (do not contain cancer), but virtually all colon cancer begins as a polyp. Therefore, removing polyps at an early stage is an effective way to prevent colon cancer.

When polyps are found at an early stage they are usually removed easily and completely. Polyps can grow and eventually contain cancer. When colon cancer is found at later stages it is often fatal.

What does colonoscopy prep involve?

Prior to the test, the patient undergoes a colon preparation to empty the colon. This can take one or two days, depending on each patient. The typical prep at Jefferson involves staying on clear liquids the day before colonoscopy. At noon on the same day, two laxative pills are taken. At 5 p.m., the patient consumes 1 liter of Gatorade, which includes a laxative powder. At 4 a.m. on test day, a second 1 liter dose of Gatorade mixed with laxative is taken. This liter must be completely finished so that the patient takes nothing by mouth for at least 3 hours before the procedure. This is to avoid the risk of aspiration (or inhaling any stomach contents that might be refluxed) of any fluid into the lungs.

It is also important that the patient consumes several liters of fluid throughout the day before the exam to stay well-hydrated, because the prep leads to frequent stools and even diarrhea.

In addition, talk to your doctor to get explicit instructions regarding any medication you are taking on a regular basis before preparing for colonoscopy. If you are taking a blood thinner such as Coumadin, adjustments have to be made to decrease the risk of bleeding. Other over-the-counter medications that can also thin your blood and should be discussed include aspirin and pain relievers, such as Advil®, Motrin®, Aleve® or any form of ibuprofen. 

How is colonoscopy performed & how long does it take?

Colonoscopy is an outpatient procedure. Sedation is administered by a certified nurse anesthetist. This "conscious sedation" makes a patient very sleepy and relaxed, but it does not involve general anesthesia. While lying on the left side on a comfortable stretcher, the thin flexible tube is inserted through the anus and the entire colon is examined. There is a small video camera inside the scope that gives the physician a clear view, and pictures can be taken of any abnormal findings. Most often, the exam takes less than 30 minutes, but sometimes longer if multiple polyps are found.

Is there any pain or discomfort after the procedure?

Following the procedure, the patient remains in the recovery area for about one hour to ensure that the vital signs are stable and that he/she can tolerate juice and crackers without getting sick. The colon is insufflated with air during the exam, so some retained gas is common. The patient may experience cramping or bloating, and may pass gas for several hours. The average patient is fully recovered and back to a normal routine on the following day.

The doctor will talk to the patient and review the findings of the exam. The nurse will again read and review written discharge instructions from the doctor before the patient leaves the Endoscopy Unit. In rare instances a patient may develop side effects and should call the doctor immediately if experiencing any of the following:

  • Severe abdominal pain
  • Fever
  • Rectal bleeding
  • Vomiting
  • Weakness
  • Dizziness

Because sedation is administered, each patient must be accompanied by a relative or friend at discharge. The restrictions following sedation include no driving for 24 hours and no drinking of alcohol for 24 hours.

At what age should colonoscopy begin & how often should it be repeated?

Studies suggest that age 50 is the time to begin routine screening to look for early signs of colon cancer. However, there are certain risk factors that lead some patients to begin colonoscopy at a younger age.

  1. A patient is at increased risk if a first-degree (parent, sibling, child) relative has had colon polyps or colon cancer. The formula determining the first screening exam considers the age when the affected relative was diagnosed. For example, if a parent is diagnosed at age 50, then screening should begin when the patient is 10 years younger. Here, the new patient would begin routine screening at age 40.
  2. A personal history of colon polyps or colon cancer
  3. A personal history of inflammatory bowel disease including Crohn's disease or ulcerative colitis
  4. A personal history of uterine or ovarian cancer before the age of 50


When the colonoscopy is repeated will be determined by the findings at the initial examination. If a patient has no polyps and no family history or other risk factors listed above, they are often instructed to return in 10 years. The important point to remember is that a patient should call his/her doctor and return immediately if he/she develops new symptoms or signs such as rectal bleeding, change in bowel habits or abdominal pain. A patient might also need repeat colonoscopy sooner if a new diagnosis of colon polyps or colon cancer is made in a family member.

If a patient has no polyps or cancer, but they have a family history of colon polyps or cancer, they will likely be asked to return for colonoscopy every five years.

For patients who do have colon polyps found during the exam, they will be asked to return at a time interval depending on how many polyps are found, how large they are and the pathology report. Each case will be discussed in great detail with the doctor who performed the colonoscopy exam. If multiple polyps are found, the exam may have to be repeated in three years. If a very large polyp is found, colonoscopy may even be repeated within one year to ensure that all the polyp tissue was removed.