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Flexible Sigmoidoscopy 


A flexible sigmoidoscopy is a procedure that uses a sigmoidoscope to view the inside lining of the rectum and lower section of the colon. A sigmoidoscope is a thin tube that is about twenty inches long. It has a light and a viewing instrument that sends images to an eyepiece or a video monitor.

The sigmoidoscope allows a doctor to examine the inside of the rectum and lower colon for cancer, polyps, and other medical conditions. A sigmoidoscope can obtain a tissue sample or biopsy. A flexible sigmoidoscopy is an outpatient procedure that does not require anesthesia or sedation.

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Your body absorbs nutrients and removes waste products via your digestive system.  Whenever you eat and drink, food travels through your digestive system for processing. As water from the waste product is absorbed, the product becomes more solid and forms a stool or feces. Eventually, it is eliminated from your body when you have a bowel movement.

After you swallow food, it moves through your esophagus and into your stomach.  Chemicals in your stomach break down the food into a liquid form. The processed liquid travels from your stomach to your small intestine. Your small intestine breaks down the liquid even further so that your body can absorb the nutrients from the food you ate. The remaining waste products from the small intestine travel to the large intestine.

Your large intestine, also called the large bowel or colon, is a tube that is about 5 feet long and 3 or 4 inches around. The lower GI tract is divided into sections, including the cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, anal canal, and anus. The appendix is located on the cecum, but it does not serve a purpose in the digestive process. 

The first part of the colon absorbs water and nutrients from the waste products that come from the small intestine. As the colon absorbs water from the waste product, the product becomes more solid and forms a stool.

The large intestine moves the stool into the sigmoid colon, where it may be stored before being traveling to the rectum. The rectum is the final 6-inch section of your digestive tract. No significant nutrient absorption occurs in the rectum or anal canal.

From the rectum, the stool moves through the anal canal. It passes out of your body through your anus when you have a bowel movement.

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A sigmoidoscopy is ordered for several reasons. It is most frequently used as a screening tool for colon cancer. It is also helpful for determining the cause of bleeding, pain, bowel obstruction, or changes in bowel habits. Additionally, a sigmoidoscope can be used for taking photographs and/or obtaining tissue samples for examination.

A flexible sigmoidoscopy is an outpatient procedure performed at a doctor’s office or in a hospital. It does not require sedation or anesthesia. Preparation instructions for a sigmoidoscopy generally consist of methods to empty or clean your bowel prior to the test, including the use of laxatives, enemas, or a liquid diet. Your doctor will provide you with specific instructions.

The Procedure

You will wear an examination gown for your flexible sigmoidoscopy. You will lie on your left side with your knees bent for the procedure, also known as the fetal position.  A digital rectal examination may be performed before the test. To do so, your doctor will briefly insert a gloved, lubricated finger into your rectum to check for abnormalities such as obstructions.

Your doctor will carefully insert the sigmoidoscope through your anus into your rectum and the lower section of your colon. Air and water may be inserted with the scope to open the folds of the colon to provide a better view. Your doctor will carefully and slowly advance the sigmoidoscope into your colon. You may need to change positions during the procedure to allow your doctor to best place the sigmoidoscope.

The procedure may cause temporary discomfort. It is common to pass gas during and after a flexible sigmoidoscopy. You may experience mild cramping and bleeding after your flexible sigmoidoscopy. Your doctor will instruct you on how to increase your food and liquid intake. Your doctor will also discuss unexpected symptoms related to the test that may occur and a plan to address them. 

Your doctor will review the results of your flexible sigmoidoscopy with you after your procedure or during a follow-up appointment. It may take time to receive biopsy results. If any abnormal results were found by your test, your doctor will discuss treatment plan options with you.

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This information is intended for educational and informational purposes only. It should not be used in place of an individual consultation or examination or replace the advice of your health care professional and should not be relied upon to determine diagnosis or course of treatment.

The iHealthSpot patient education library was written collaboratively by the iHealthSpot editorial team which includes Senior Medical Authors Dr. Mary Car-Blanchard, OTD/OTR/L and Valerie K. Clark, and the following editorial advisors: Steve Meadows, MD, Ernie F. Soto, DDS, Ronald J. Glatzer, MD, Jonathan Rosenberg, MD, Christopher M. Nolte, MD, David Applebaum, MD, Jonathan M. Tarrash, MD, and Paula Soto, RN/BSN. This content complies with the HONcode standard for trustworthy health information. The library commenced development on September 1, 2005 with the latest update/addition on April 13th, 2016. For information on iHealthSpot’s other services including medical website design, visit