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Medically reviewed by Last updated on May 10, 2023.

What is Sigmoidoscopy?

Harvard Health Publishing

Sigmoidoscopy is an examination of the rectum and the bottom part of the colon. To do this exam, your doctor uses a sigmoidoscope—a flexible viewing tube with a light and a lens or video camera on one end, and an eyepiece or video monitor on the other. The sigmoidoscope allows your doctor to see the inside of your bowel through fiber optic technology.


During sigmoidoscopy, your doctor will be looking for signs of inflammation, ulcers, and polyps. The procedure usually takes less than 15 minutes, and can be done in your doctor's office. There is usually very little discomfort because the sigmoidoscope is lubricated and bends easily.

What It's Used For

Sigmoidoscopy is used to diagnose certain bowel problems such as unexplained bleeding, diarrhea, constipation or rectal pain. If your doctor sees a suspicious area, he can use an attachment at the end of the sigmoidoscope to remove a piece of tissue and send it to the laboratory to be examined under a microscope. This is called a biopsy. If your doctor finds an abnormal area during the test, he or she may recommend a more comprehensive test called a colonoscopy.

Sigmoidoscopy is also used as a screening test to check for colorectal cancer. It usually is done once every 5 years, beginning at age 50. It may be combined with fecal occult blood testing to ensure that cancer is not missed in the upper part of the colon. As an alternative, your doctor may recommend cancer screening with a colonoscopy, usually once 10 years for people at average risk.


The last part of your large intestine needs to be fairly empty during sigmoidoscopy to give your doctor a clear view of your intestinal wall. To help empty your bowel, your doctor will give you specific directions about using enemas the day of the procedure. In some cases, you may need to use laxatives the day before the procedure. On the day of your appointment, you may be asked to not eat or to limit yourself to mostly liquids. Your doctor will give you more details about diet when you schedule your sigmoidoscopy.

Your doctor may tell you to stop taking certain medications for a few days before the test. Be sure to review your medications with your doctor, especially if you take any type of blood thinner or iron.

How It's Done

The procedure will be explained, and you will be asked to sign a consent form. You may be asked for basic information about your medical history, the medications you take and your allergies.

Then you will put on a hospital gown, and your doctor's assistant will record your temperature, pulse, blood pressure and respiratory rate (number of breaths per minute). You will lie on your side on an examination table, with one or both of your knees raised to your chest. The lower part of your body will be covered with a sheet.

The doctor will insert a lubricated, flexible sigmoidoscope into your rectum and, as necessary, pump a small amount of air through the sigmoidoscope to inflate your intestinal passage for a clearer view. Your doctor also may take a stool sample or a piece of tissue for a biopsy.

Although people often worry that they will be uncomfortable during a sigmoidoscopy, you should not feel anything worse than a sense of pressure or mild cramping. Pain medications or sedatives rarely are needed, and the procedure often takes as few as five minutes to complete. Tell your doctor immediately if you develop severe pain or other type of discomfort during the procedure.


After sigmoidoscopy is complete, you can get dressed and return to your normal diet and daily schedule. If your doctor took a stool sample or tissue for a biopsy, check back in a few days for the results.


Although it is possible for the bowel to be injured during sigmoidoscopy, this complication is rare, occurring in about 1 in 10,000 procedures.

When To Call a Professional

Call your doctor immediately if you see any bleeding from your rectum after sigmoidoscopy. Call if you feel faint, dizzy, short of breath or have palpitations. Call your doctor if you have nausea, vomiting, cramps or any other type of abdominal pain, or if you develop a fever, chills, severe headache or muscle aches.

Additional Info

National Institute of Diabetes & Digestive & Kidney Disorders

American Society for Gastrointestinal Endoscopy (ASGE)

National Library of Medicine (NLM)

American Cancer Society (ACS)


Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.