by Scholten A

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A flexible sigmoidoscopy is an exam of the rectum and lower colon (large intestine). The exam is done with a thin tube called a scope. The scope has a tiny camera on the end. It allows the doctor to see inside the rectum and colon.

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Reasons for Procedure

Flexible sigmoidoscopy is used to look for and treat problems in the rectum and lower colon. The most common reasons for the procedure are to:

  • Take tissue samples for testing—known as a biopsy
  • Look for the cause of lower belly pain, bleeding, or problems with passing stool
  • Look for and remove colon polyps —some polyps can become cancer
  • See if treatment for inflammatory bowel disease is working
  • Screen for colon and rectal cancers

Possible Complications

Problems are rare, but all procedures have some risk. The doctor will go over some problems that could happen, such as:

Things that may raise the risk of problems are:

  • Smoking
  • Drinking
  • Prior surgery or radiation therapy to the area
  • Chronic diseases, such as diabetes or obesity

What to Expect

Prior to Procedure

The care team may meet with you to talk about:

  • Anesthesia options
  • Any allergies you may have
  • Current medicines, herbs, and supplements that you take and whether you need to stop taking them before the procedure
  • Fasting before the procedure, such as avoiding food or drink after midnight the night before
  • Whether you need a ride to and from the procedure
  • Cleaning out the colon


The doctor may give a sedative. You will feel relaxed.

Description of the Procedure

The doctor will do a rectal exam. The scope will then be slowly inserted into the rectum. The doctor will pass the scope through the rectum and into the colon. It will inject air into the colon to open the area. The camera on the scope will send images to a monitor in the room. The doctor will be able to see the walls of the colon as the scope moves through.

Other tools can be passed through the scope. The tools may remove a sample of tissue or polyps. The tissue can then be sent for testing. The scope will be removed once the doctor is done.

How Long Will It Take?

About 20 to 30 minutes.

Will It Hurt?

There may be some discomfort when the scope is inserted. Some cramping or lower belly pain can happen during the procedure. Medicine will help to ease discomfort. Some will sleep through the procedure.

Gas pains and cramping are common after. These pains should go away with the passing of gas.

Post-procedure Care

Most can go home after 1 to 2 hours. It will take the rest of the day to recover. There may be a small amount of bleeding during the first few days after the procedure.

It may take 1 to 2 weeks to get results back from tissue sample. Other tests may be needed.

Call Your Doctor

Call your doctor if you are not getting better or you have:

  • Increased bleeding from the rectum
  • Black, tarry stools
  • Severe belly pain
  • Hard, swollen belly
  • Signs of infection, such as fever or chills
  • Nausea and vomiting
  • Problems passing gas or stool
  • Chest pain or trouble breathing

If you think you have an emergency, call for medical help right away.


American Society for Gastrointestinal Endoscopy 

National Institute of Diabetes and Digestive and Kidney Diseases 


Canadian Association of Gastroenterology 

Canadian Digestive Health Foundation 


Flexible sigmoidoscopy for colorectal cancer screening. EBSCO DynaMed website. Available at: Accessed February 15, 2021.

Flexible sigmoidoscopy. National Institute of Diabetes and Digestive and Kidney Diseases website. Available at: Accessed February 15, 2021.

Ko CW, Doria-Rose VP, et al. Screening flexible sigmoidoscopy versus colonoscopy for reduction of colorectal cancer mortality. Int J Colorectal Dis. 2019;34(7):1273-1281.

Understanding flexible sigmoidoscopy. American Society for Gastrointestinal Endoscopy website. Available at: Accessed February 15, 2021.

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