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Farmington Hills, MI 48336-5919
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Health Information

Colonoscopy

(Lower Endoscopy)

Procedure overview

Illustration of the anatomy of the digestive system, adult
Click Image to Enlarge

What is a colonoscopy?

Colonoscopy is a diagnostic procedure that allows the doctor to examine the entire length of the large intestine. Colonoscopy can assist in identifying problems with the colon, such as early signs of cancer, inflamed tissue, ulcers, and bleeding. Colonoscopy is also used to screen for colorectal cancer, the second leading cause of cancer-related deaths in the U.S. and the fourth most common cancer in men and women.

An endoscope, which is a long, flexible, lighted tube (also called a colonoscope), is inserted through the rectum into the colon. In addition to allowing visualization of the internal colon, the colonoscope enables the doctor to irrigate, suction, inject air, and access the bowel with surgical instruments. During a colonoscopy, the doctor may remove tissue and/or polyps for further examination and possibly treat any problems that are discovered.

Other related procedures that may be used to assess problems of the colon include abdominal X-ray, computed tomography (CT scan) of the abdomen, abdominal ultrasound, barium enema, and sigmoidoscopy. Please see these procedures for additional information.

Anatomy of the colon

The large intestine, or colon, has four sections:

The rectum joins the anus, or the opening where waste matter passes out of the body.

Screening guidelines for colorectal cancer

Colorectal cancer screening guidelines for early detection from the American Cancer Society recommend that beginning at age 50, both men and women should follow one of the examination schedules below:

People with any of the following colorectal cancer risk factors should begin screening procedures at an earlier age and be screened more often:

Reasons for the procedure

A colonoscopy may be used to examine colon polyps, tumors, ulceration, inflammation, diverticula (pouches), strictures (narrowing), and foreign objects within the colon. It may also be used to determine the cause of unexplained chronic diarrhea or gastrointestinal bleeding or to evaluate the colon after cancer treatment.

Colonoscopy may be indicated when the results of a barium enema and/or sigmoidoscopy warrant further examination of the colon.

There may be other reasons for your doctor to recommend a colonoscopy.

Risks of the procedure

As with any invasive procedure, complications may occur. Complications related to colonoscopy include, but are not limited to, the following:

There may be other risks depending on your specific medical condition. Be sure to discuss any concerns with your doctor prior to the procedure.

Certain factors or conditions may interfere with a colonoscopy. These factors include, but are not limited to, the following:

Before the procedure

Illustration demonstrating a colonoscopy, part 1
Click Image to Enlarge

During the procedure

A colonoscopy may be performed on an outpatient basis or as part of your stay in a hospital. Procedures may vary depending on your condition and your doctor's practices.

Generally, the colonoscopy follows this process:

  1. You will be asked to remove any jewelry or other objects that may interfere with the procedure.

  2. You will be asked to remove your clothing and given a gown to wear.

  3. An intravenous (IV) line may be inserted in your arm or hand. A sedative and/or pain medication may be injected into the IV.

  4. Your heart rate, blood pressure, respiratory rate, and oxygen level will be monitored during the procedure.

  5. You will be asked to lie on your left side with your knees bent towards your chest.

  6. A lubricated colonoscope will be inserted into the anus and advanced into the rectum and colon. You may experience mild pain, pressure, and/or cramping during the procedure. A sedative is given to lessen the discomfort.

  7. You may be asked to take slow, deep breaths while the tube is being inserted to relax the abdominal muscles and decrease the discomfort. You may also be asked to change your position to aid the passage of the colonoscope.

  8. Air may be injected into the bowel to aid visualization. In addition, a water jet may be used to cleanse the lining of the colon and a suction device may be used to remove liquid feces.

  9. The doctor will examine the colon and may take photographs. If a polyp is seen, it may be removed, biopsied, or left alone until a subsequent operation is performed.

  10. After the procedure has been completed, the colonoscope will be removed.

After the procedure

After the procedure, you will be taken to the recovery room for observation. Your recovery process will vary depending on the type of sedation that is given. Once your blood pressure, pulse, and breathing are stable and you are alert, you will be taken to your hospital room or discharged to your home.

You may be asked to fast for a few hours and avoid foods high in fiber content for the first 24 hours after the procedure.

You may experience flatulence (passing of gas) and gas pains after the procedure. This is normal. Walking and moving about may help to ease any discomfort.

Alcohol should be avoided for at least 24 hours after sedation. You may be encouraged to drink extra fluids to make up for the water lost during preparation for the procedure.

Notify your doctor to report any of the following:

Following a colonoscopy, your doctor may give you additional or alternate instructions after the procedure, depending on your particular situation.

Online resources

The content provided here is for informational purposes only, and was not designed to diagnose or treat a health problem or disease, or replace the professional medical advice you receive from your doctor. Please consult your health care provider with any questions or concerns you may have regarding your condition.

This page contains links to other websites with information about this procedure and related health conditions. We hope you find these sites helpful, but please remember we do not control or endorse the information presented on these websites, nor do these sites endorse the information contained here.

American Cancer Society

American College of Gastroenterology

American Gastroenterological Association

National Cancer Institute (NCI)

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

National Institutes of Health (NIH)

National Library of Medicine