To watch ASGE’s educational video about what to expect during a colonoscopy, click here.

What is a colonoscopy?

A colonoscopy is an exam used to see inside the colon and rectum to detect any changes or abnormalities. A long flexible tube (colonoscope) about the thickness of a finger is inserted into the rectum and passed through the large intestine (colon). A tiny video camera at the tip of the tube allows the doctor to carefully examine the lining of the colon.

During the course of the examination a polyp may be found. Polyps are abnormal growths of tissue which vary in size from a tiny bump to several inches. If your doctor feels removal of the polyp can be completed safely, the tissue will be removed through the scope during the procedure. Although the majority of polyps are benign (noncancerous), a small percentage may contain an area of cancer in them or may develop into cancer. Removal of colon polyps is an important means of prevention and cure of colon cancer.

The doctor may also take tissue samples (biopsies) during the procedure to evaluate an area of the colon lining.

Why should I have a colonoscopy?

Colonoscopies are recommended for a number of reasons.
• To screen for colon cancer. If you are age 50 or older, your doctor may recommend a colonoscopy to screen for colon cancer. Colonoscopy is one option for colon cancer screening. It is important to talk with your doctor about your options.
• To check for more polyps. If you have had polyps removed, your doctor may recommend a follow-up colonoscopy to check for and remove any new polyps. Follow-up recommendations are based on the type of polyp you had and are done to reduce your risk of colon cancer.
• To investigate intestinal signs and symptoms. This type of colonoscopy is considered a diagnostic exam. It is done to explore possible causes of abdominal pain, rectal bleeding, changes in bowel habits, constipation, diarrhea, and other abdominal symptoms.

What are the complications of a colonoscopy?

Colonoscopy is generally safe when performed by doctors who have been specially trained and are experienced in the procedure. Although complications are uncommon, they do occur and can include:
• Adverse reaction to the sedation
• Bleeding from a polyp or biopsy site
• A tear in the colon or rectum wall (perforation)
Your doctor will discuss the risks of colonoscopy with you. It is important to recognize early signs of possible complications. Contact your doctor if you notice severe abdominal pain, fever and chills, or rectal bleeding of more than one-half cup. It should be noted bleeding can occur several days after the procedure.

How do I prepare for a colonoscopy?

Before a colonoscopy, you will be asked to clean out your colon so the doctor can see the colon lining. Any residue in your colon may make it difficult for the doctor to view the lining and may result in missed polyps or abnormalities.

To clean out your colon you will be given instructions specially chosen for you. These instructions will include information on the following:
• Special diet
• Laxative use
• Medication instructions
It is very important these instructions are followed to ensure you have the best clean out possible. Once you have started the laxative process the day before your exam, you should plan on remaining close to a restroom.
Notify the doctor of all the medications you are taking. Most medications can be continued as usual, but some medications may need to be adjusted or stopped temporarily prior to the exam. The doctor’s office will discuss any medication changes with you prior to the colonoscopy.

What can I expect during and after the colonoscopy?

Right before your exam, a nurse will have you change into a gown. Your medical history will be reviewed, vital signs taken, and an IV will be started for sedation purposes. You will speak with a nurse anesthetist about your sedation options.

Once you enter the procedure room, the physician will speak with you regarding your procedure, any concerns you have, and have you sign a procedure consent. Sedation will be given after all your questions have been answered and you have signed your consent.

You will begin the procedure by lying on your left side on the exam table with your knees bent. The doctor will insert a colonoscope into your rectum. The colonoscope contains a light and an air channel. The air channel allows the doctor to inflate your colon to provide a better view of the colon lining. When air is introduced or the scope is moved, you may feel some abdominal cramping and the urge to have a bowel movement.

The tip of the colonoscope also contains a tiny video camera that sends images to a monitor so the doctor can see the inside of your colon. The doctor can take pictures of the inside of your colon to record any findings during the exam.

The doctor can also insert instruments through the colonoscope to take tissue samples or remove any polyps or other areas of abnormal tissue.

A colonoscopy usually takes 20 minutes to 1 hour to complete, although you should plan on 2 to 3 hours for waiting, preparation, and recovery.

After the exam you will be taken back to the recovery area. The doctor will give you and your driver (if authorization given) a report of the procedure. You will have to wait for the results of any polyps or biopsies taken. Because you will still be sleepy from the sedation, you may not remember talking with the doctor. The nurse will go over your results and any home instructions with you and your driver.

It can take up to a full day for the effects of the sedation to wear off. Because of the sedation, you will need to have someone to take you home and you are not to go back to work for the rest of the day. If you do not have a driver or a responsible adult to accompany you home, your procedure will be cancelled.

You may feel bloated and pass gas for a few hours after the exam. Walking may help to relieve any discomfort and assist you in passing the air.

After the exam, you may notice a small amount of blood with your first bowel movement. A small amount of blood is not cause for alarm. You will need to call your doctor or seek medical attention if you continue to pass blood or blood clots, have persistent abdominal pain, or develop a fever of 100 F (37.8 C) or higher.

Results of colonoscopy

Your doctor will review your results and send you a letter with the results and follow-up recommendations. It may take 2-4 weeks to receive your letter.

If the doctor doesn’t find any abnormalities in your colon, the exam is considered negative. If you are at an average risk for colon cancer (no risk factors other than age) your doctor may recommend follow-up in 10 years.

If the doctor finds any polyps or abnormal tissue in the colon, the exam is considered positive. Polyps removed during a colonoscopy are sent to a laboratory to determine if they are noncancerous, precancerous, or cancerous. Most polyps are not cancerous. Any tissue biopsies taken during a colonoscopy are sent to a laboratory for analysis.

The doctor will recommend a specialized follow-up schedule depending on the size and number of polyps found, the type of polyps found, findings of the pathology, and any other risk factors.

If the doctor was unable to view the lining of the colon due to a poor quality preparation, he or she may recommend a repeat colonoscopy or a shorter time until your next colonoscopy.