A colonoscopy is an endoscopic procedure that visually examines the entire colon with a video scope. The inside of the colon is then examined for any abnormalities that may exist. During this procedure, polyps may be safely removed.

What’s a polyp?

A polyp is extra tissue that grows inside your body. Colon polyps grow in the large intestine. The large intestine, also called the colon, is part of your digestive system. It's a long, hollow tube at the end of your digestive tract where your body makes and stores stool.

Most polyps are not dangerous. Most are benign, which means they are not cancer. But over time, some types of polyps can turn into colon cancer. Usually, polyps that are smaller than a pea aren't harmful. But larger polyps could someday become cancer or may already be cancer. To be safe, doctors remove all polyps and test them.

Why do I need a colonoscopy?

This procedure is commonly performed for evaluation of abnormal radiographic studies, removal of polyps, assessment of bleeding and screening for colon cancer.

Colonoscopy is indicated for patients with inflammatory bowel disease, GI hemorrhage, polyp removal, screening for colon cancer and evaluation of abnormal x-rays of the GI tract.

An alternative exam to assess the colon is the barium enema. CT scans of the abdomen and pelvis are useful but do not always provide sufficient information about the colon itself. CT scans are not a good test for looking at tubular structures. They are, however, excellent tests for looking at structures surrounding the colon and intestines.


An oral laxative solution is given the day before the procedure. This will cleanse the waste from the colon. It is important that the preparation be followed completely. This procedure examines the inside of the colon. Thus, if feces are retained, or the preparation is inadequate, areas of the colon that may be of importance to your health may be missed or misinterpreted. Usually the preparations given for these are excellent. If you have specific difficulties with laxatives or the preparations, please inform your physician beforehand so that alternatives can be addressed.

Please make sure that your physician knows well beforehand if you are taking any blood thinners. Specific instructions regarding the preparation are available in the section regarding preparations for procedures.

Risks of the Procedure

Colonoscopy is a safe and highly effective technique. In experienced hands, this procedure has the following risks:

  • Bleeding
  • Allergic reaction to a medication
  • Perforation of the colon

Bleeding can occur up to 10 days after the procedure if polyps are removed. The chance of bleeding will increase depending upon the number, location and size of polyps (if any) that are removed. Some patients have bleeding from hemorrhoids after the procedure. If any significant or persistent bleeding occurs notify doctor immediately.

An allergic reaction to a medication rarely can occur. This is usually identified early, since blood pressure, heart rate, oxygen saturation and general clinical condition are monitored during the entire procedure.

Perforation of the colon is a rare complication that occurs when a hole is put through the colon. This can be associated with removal of polyps or simply passing the endoscope through the colon. This will usually result in a patient being treated in the operating room. Overall, colonoscopy is a well-tolerated procedure that has many benefits and few complications when done for appropriate reasons by an experienced gastroenterologist.


In general, this procedure takes approximately 30 to 45 minutes to perform when done by a trained gastroenterologist. The procedure may take longer depending upon the intervention that may be required for any individual patient.

During the procedure, a video endoscope will be inserted into the anus. The scope will then be advanced through the inside of the colon to the cecum (last part of the colon). Inspection, removal of polyps, etc. usually occur during withdrawal of the endoscope.

The appropriate anesthesia for your procedure will be determined by your physician. Our goal is to provide a comfortable examination for you.

During the procedure, the nurse assisting your physician with the procedure will continuously monitor your heart rate, oxygen saturation and blood pressure. Thus, should any difficulties occur, your physician and his team will be aware of the change quickly.


After the procedure, the physician will discuss the results with the family and/or the patient. In many cases, the patient will not recall having talked with their physician. This is a natural and understandable event, since some medications used during the procedure will induce a temporary amnesia.

After the procedure, patients are returned to a recovery area where they are monitored during their stay for 30-60 minutes. When the patient is stable, he or she will be discharged.

Patients must have someone to drive him or her home after conscious sedation (analgesics) has been administered.

To assist our patients, a written explanation of the procedure and its findings, in lay terms, will be given to the patient. Recommendations will be made regarding any further testing, treatments or office visits. A summary of the endoscopic record is sent to referring physicians. Thus, your primary care physician will be aware of your procedure, the results and your gastroenterologist's recommendations.

For More Information

To learn more about this topic, visit:
American Gastroenterological Association (AGA)