Flexible Sigmoidoscopy

Flexible sigmoidoscopy, sometimes shortened to flex sig, allows the physician to look at the inside of the large intestine from the rectum through the last part of the colon, called the sigmoid or descending colon. The colon is 5 to 6 feet long. Flexible sigmoidoscopy examines the last 1 to 2 feet of the colon.

Reasons for the Exam

Physicians may use this procedure to find the cause of diarrhea, abdominal pain, or constipation. They also use it to look for early signs of cancer in the descending colon and rectum. With flexible sigmoidoscopy, the physician can see bleeding, inflammation, abnormal growths, and ulcers in the descending colon and rectum. Flexible sigmoidoscopy is not sufficient to detect polyps or cancer in the ascending or transverse colon (two-thirds of the colon).


The flexible sigmoidoscopy uses a flexible instrument that can be steered around the bends in the lower colon and rectum. The instrument has an optically sensitive chip in the tip that transmits an image to a video screen. Dials permit the physician to steer the instrument in every direction. An open channel in the scope allows other instruments to be passed through it in order to perform biopsies, remove polyps or inject solutions.


The benefit of the flexible sigmoidoscopy is that it may allow the physician to make a diagnosis or correct problems during the Gastroenterology procedure. Polyps or tumors in the lower portion of the colon can be discovered at an early stage. Conditions such as colitis or diverticulosis may be monitored and treatment adjusted accordingly.

Risks and Side Effects

No test is 100% accurate. Flexible sigmoidoscopy may miss abnormalities that are present. The test only examines the final portion of the colon. Abnormalities higher in the colon cannot be detected by this test.

Sigmoidoscopy is a very safe procedure and complications are uncommon. Temporary bloating is common. If biopsies are done or if a polyp is removed, there may be bleeding. Bleeding is general minimal and rarely serious. Other less frequent complications may include a tear in the wall of the colon which may require surgery.


The lower portion of your colon must be empty during the flexible sigmoidoscopy so that the doctor can examine the walls of your colon. This requires a laxative preparation and a restricted diet.

View the Flexible Sigmoidoscopy Preparation instructions.

Alternative Testing

Alternative testing includes barium enema x-rays. The barium enema does not allow the physician to directly look at the lower colon. In addition polyps cannot be removed nor biopsies taken during the barium enema.

Before the Procedure

You will be asked to arrive well ahead of the scheduled procedure time. Please bring your insurance cards with you. It is advised that you leave your valuables at home or with whomever accompanies you.

The flexible sigmoidoscopy procedure is most often performed without sedation. However, if you physician has determined that you should receive sedation medication during your procedure, you must have someone to drive you home or the procedure will not be performed.

When you arrive for your procedure, a brief medical history will be reviewed with you by a nurse. Please bring a list of your current medications and any allergies. You will be asked to remove your clothing and change into a patient gown.

The Procedure

The flexible sigmoidoscopy examines only the final portion of the colon. It is generally not painful and usually requires no sedation. If your doctor has chosen sedation for your procedure, an intravenous (IV) catheter will be placed into your arm so that medications can be given for sedation. Most of the effects of the sedation persist for 15-60 minutes, and you may not be able to recall the procedure afterwards.

Flexible sigmoidoscopy takes 10 to 20 minutes. For the procedure, you will lie on your left side on the examining table. The physician will insert a short, flexible, lighted tube into your rectum and slowly guide it into your colon. The tube is called a colonoscope. The scope transmits an image of the inside of the rectum and colon, so the physician can carefully examine the lining of these organs. The scope also blows air into these organs, which inflates them and helps the physician see. During the procedure, you might feel pressure and slight cramping in your lower abdomen. You will feel better afterward when the air leaves your colon.

If anything unusual is in your rectum or colon, like a polyp or inflamed tissue, the physician can remove a piece of it using instruments inserted into the scope. The physician will send that piece of tissue (biopsy) to the lab for testing.

Bleeding and puncture of the colon are possible complications of sigmoidoscopy. However, such complications are uncommon.

After the Procedure

In most cases, sedation during flex sig is not required, and you will be able to leave as soon as the procedure is over and the physician discusses the results with you. If you receive sedation, you will remain in the recovery area for one-half to one hour after the procedure, depending on your vital signs and level of consciousness.


Following the exam, your physician will discuss the results with you and your family. If you want family members to hear the results of your test, they should remain in the waiting area for the duration of your stay.

If you have additional questions, please view our FAQs.

Dayton Gastroenterology, Inc.

  • Beavercreek (Sylvania) Office & Endoscopy Center - 75 Sylvania Drive, Beavercreek, OH 45440 Phone: 937-320-5050 Fax: 937-320-5060
  • Beavercreek (Indian Ripple) Office & Endoscopy Center - 4200 Indian Ripple Road, Beavercreek, OH 45440 Phone: 937-320-5050 Fax: 937-320-5060
  • Englewood Office & Endoscopy Center - 9000 N. Main Street Suite 405, Englewood, OH 45415 Phone: 937-320-5050 Fax: 937-320-5060
  • Miamisburg Office - 415 Byers Road Suite 100, Miamisburg, OH 45342 Phone: 937-320-5050 Fax: 937-320-5060

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