Colonoscopy Procedure & Prep | MedStar Health
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A polyp is seen on the monitor during a colonoscopy, a test that helps diagnose colorectal cancer.

A colonoscopy is a test that allows your doctor to look at the inner lining of your whole colon and small intestine. A thin, flexible, lighted tube, called a colonoscope, with a small video camera attached is inserted into the rectum and entire colon to find ulcers, colon polyps, tumors, and areas of inflammation or bleeding.

During a colonoscopy, tissue samples can be collected (biopsy) and abnormal growths can be taken out. Colonoscopy can also be used as a screening test to check for cancer or precancerous growths in the colon or rectum (polyps).

Colonoscopies are recommended as a way to prevent colorectal cancer; when performed regularly (usually suggested for people over 50, though those with a family history of colon cancer or colon polyps may need to be screened earlier) they can aid in diagnosing colon cancer at an early and treatable stage.

Colonoscopies can also be used to screen for numerous other conditions, including:

Due to the numerous regulations in a hospital environment, patients can rest assured that their procedure will be safe and meet the highest quality standards.


Before this test, you will need to clean out your colon with medication and a clear liquid diet. Colon prep can take 1 to 2 days, depending on which type of prep your doctor recommends. Plan to stay home during your prep since you will need to use the bathroom often.

Instructions for patients undergoing colonoscopies:

  • You must have a responsible adult to accompany you home after the procedure.
  • You may not operate a motor vehicle for the remainder of the day following your procedure.
  • You may not take a taxi or bus home unless accompanied by a responsible adult.
  • If you do not have a responsible adult to accompany you home, your procedure will be canceled.

The day before your procedure

  • Drink only clear liquids the entire day. No solid food should be taken. Clear liquids include: water, bouillon, apple juice, white grape juice, pulp-free lemonade, Sprite, ginger-ale, coffee or tea without milk or non-dairy creamers, and plain Jell-O (no added fruit or toppings and no red, purple, or blue Jell-O).
  • Colyte, Trilyte, Nulytely, or Golytely Prep: mix the powder in the provided plastic containers with water to the fill line and chill in the refrigerator. Begin drinking the solution at approximately 4 p.m. Drink one 8-ounce glass every 10 to 15 minutes until complete in about 4 hours. You must drink the entire container of solution. If your stools are not completely clear (pale yellow to clear fluid) after taking the entire solution, you should take one 10-ounce bottle of magnesium citrate. This can be purchased without a prescription at any drug store.
  • You may add Crystal Light powdered lemonade to the solution to improve its taste.
  • No solid foods may be taken during or after the prep.
  • Once the prep is complete you may drink water until midnight.
  • You may not have anything to eat or drink after midnight or on the day of your procedure.
  • If you are on insulin or other diabetic medication, check with your primary or referring physician for instructions.
  • If you are over age 50 and have recently had an electrocardiogram (EKG), bring a copy of the EKG tracing with you or have your primary physician fax a copy.
  • If you are on blood thinners (e.g., coumadin, heparin, Lovenox, Plavix, etc.), consult with your referring physician.

The day of your procedure

  • Do not eat hard candy or chew gum.
  • Wear comfortable clothing that is easy to remove and leave jewelry at home.
  • Limit your visitors to one to two adults.
  • Once registered, you will be asked to put on a hospital gown. A nurse will review your medical history with you (bring a list of your current medications and allergies). An intravenous line (IV) will be started for your sedation during the procedure.
  • Your heart rate, blood pressure, and oxygen level will be monitored during the procedure.
  • When your procedure is done, you will remain in the recovery room for up to 1 hour.
  • Your doctor will discuss the results of your procedure with you and give you a written copy of the report.

After the test

Depending on where you have a colonoscopy, you may need to remain at the physician's office or you will be allowed to leave with a ride home. You will be able to return to your normal diet and routine. You should drink a lot of fluids following the test but do not drink alcohol. You may experience diarrhea, cramping, and sharp pain.

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Additional information

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If you are age 50 or older, put your fears aside and schedule your colonoscopy, a painless screening that could save your life. Learn more about the procedure in the video above: