Colonoscopy is an outpatient procedure to examine the large intestine (colon) and rectum for polyps, ulcerations, diverticulitis and early signs of colorectal cancer. An endoscope — a long, flexible, lighted tube (also called a colonoscope), is inserted into the rectum and gently advanced through the intestine. Colonoscopy is done for routine screenings, to determine the cause of symptoms such as diarrhea or rectal bleeding, or to evaluate the colon after cancer treatment. During a colonoscopy, your surgeon may remove tissue for further examination (biopsy).

Board certified colon and rectal surgeons at Brigham and Women’s Hospital (BWH) perform a high volume of colonoscopies annually. We use the most advanced technologies for colonoscopy, improving polyp detection and reducing colon and rectal cancer risk.

The American Cancer Society recommends that men and women have a colonoscopy every 10 years, beginning at age 50. People with inflammatory bowel disease or a history of colon cancer or rectal cancer are advised to get a colonoscopy at an earlier age and to be screened more often. Learn more about colonoscopy.

Colonoscopy Topics

Risks of Colonoscopy

As with any invasive procedure, rare complications may occur. Complications related to colonoscopy include:

  • Persistent bleeding after biopsy or polyp removal
  • Peritonitis (inflammation of the lining of the abdominal cavity)
  • Perforation of the intestinal wall (rare)
  • Nausea, vomiting, bloating, or rectal irritation caused by the bowel cleanse prep and/or procedure
  • Adverse reaction to the sedative or pain medication

Learn more about colonoscopy risks.

Preparing for Colonoscopy

Before your colonoscopy procedure:

  • Tell your doctor about your medications and health conditions.
  • Discuss the risks of the test with your doctor.
  • Your rectum and colon must be empty for the test. Follow the diet and bowel prep instructions exactly.
  • Ask your doctor whether you need to have someone drive you home after the test.

Learn more about preparing for colonoscopy.

During and After Colonoscopy

A colonoscopy may be performed on an outpatient basis or as part of your stay in a hospital.

You will be given sedating (relaxing) medication through an IV (intravenous) line. You may be drowsy or completely asleep.

  • The procedure takes 30 minutes or longer.
  • The doctor performs a digital rectal exam to check for anal and rectal problems. The rectum is lubricated and the scope inserted.
  • If you are awake, you may have a feeling similar to needing to have a bowel movement. You may also feel pressure as air is pumped into the colon. It is OK to pass gas during 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.

Learn more about colonoscopy during and after the procedure.

What You Need to Know about Colonoscopy Video

Jessica Allegretti, MD, MPH, describes colon cancer screening guidelines and what to expect during a colonoscopy, a colon cancer screening exam. Read the Colon Cancer Screening video transcript.

Multidisciplinary Care

Brigham and Women’s Hospital provides a multidisciplinary approach to patient care, collaborating with colleagues who have extensive experience performing colonoscopies. In addition, patients have full access to BWH’s world-renowned academic medical community with its diverse specialists and state-of-the-art facilities.


Go to our health library to learn more about colonoscopy.

Visit the Kessler Health Education Library in the Bretholtz Center for Patients and Families to access computers and knowledgeable staff.

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