Flexible Sigmoidoscopy
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Flexible Sigmoidoscopy

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A visual exam of the rectum and the lower portion of the colon, called the sigmoid colon, with an instrument called a flexible sigmoidoscope. This instrument shines light and allows the doctor to view the inside of the intestine (bowel) through a tiny video camera. Sigmoidoscopy can also be used to obtain tissue samples for testing.


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Parts of the Body Involved

The exam is intended for the sigmoid colon and rectum.

Reasons for Procedure

Flexible sigmoidoscopy is used to examine and diagnose problems inside the rectum and the sigmoid colon. The procedure is most often performed for the following reasons:

  • Obtain tissue samples for testing
  • Identify the source or cause of rectal bleeding, diarrhea, constipation, lower abdominal pain, or inflammation
  • Diagnose changes in bowel habits
  • Detect the presence of or remove polyps (small growths than can turn cancerous)
  • Monitor response to treatment in patients with inflammatory bowel disease
  • Screen for colorectal cancer
Colorectal cancer screening is recommended every 3 to 5 years for all people over 50. People with a family history of colon cancer or certain bowel diseases such as intestinal polyps, Crohn's disease , or ulcerative colitis should be screened earlier and more frequently.

Risk Factors for Complications During the Procedure

  • Pre-existing, severe heart or kidney condition
  • Treatment with certain medications, including aspirin and other drugs with anticoagulant or blood-thinning properties
  • Patient is unable to cooperate, possibly due to severe abdominal pain
  • Prior abdominal surgery or radiation treatments

What to Expect

Prior to Procedure

Your doctor will likely do the following:

  • Physical and rectal exam
  • Health history
  • Review your medications
  • Test to check for hidden blood in your stool called occult blood

In the days leading up to your procedure:

  • Your lower intestine must be completely cleaned out before the procedure. Any stool left in the intestine will block the doctor's view. This preparation may start several days before the procedure. Follow your doctor's instructions, which may include any of the following cleansing methods:
    • Enemas—fluid introduced into the rectum to stimulate a bowel movement
    • Laxatives—medications that cause you to have soft bowel movements
    • A clear-liquid diet
    • Oral cathartic medications—a large container of fluid to drink, which stimulates a bowel movement
  • When making the appointment, ask about any medication restrictions. You may need to stop taking anti-inflammatory and blood thinning medications, including aspirin and ibuprofen, 7 to 10 days before the procedure.
  • You may need to stop taking iron supplements or vitamins containing iron.
  • The night before, eat a light meal and do not eat or drink anything after midnight.
  • Wear comfortable clothing.

During Procedure:

You'll be positioned either on your left side with knees bent and drawn up toward your chest, on your back with your feet in stirrups (as for a pelvic examination), or on a special table. Try to relax and breathe slowly and deeply.


There is no anesthesia associated with a sigmoidoscopy.

Description of the Procedure

The doctor first performs a digital rectal exam. Then the doctor slowly inserts the lubricated sigmoidoscope, which is about the thickness of a human finger, through the rectum and into the colon. The scope injects air into the colon to widen the passage.

The doctor guides the instrument through the lower colon and examines the lining, looking for any abnormalities. A small video camera in the sigmoidoscope lets the doctor view an image of the colon's lining and rectum. A tissue sample and/or intestinal polyps may be removed and analyzed.

After Procedure

A laboratory will examine the removed tissue.

How Long Will It Take?

The procedure typically last about 20 to 30 minutes.

Will It Hurt?

Most patients report some discomfort when the instrument is inserted, as well as cramping, muscle spasms, or lower abdominal pain during the procedure. You may also feel the urge to move your bowels. Tell the doctor if you experience severe pain.

After the procedure, gas pains and cramping are common, but should subside with the passing of gas.

Possible Complications

  • Bleeding
  • Perforation or puncture of the bowel

Average Hospital Stay

A hospital stay is not required after a sigmoidoscopy.

Postoperative Care

  • If tissue was removed, a small amount of bleeding may occur during the first few days after the procedure.
  • Resume medications as instructed by your doctor.
  • Resume normal diet, unless directed otherwise by your doctor.


After removing the sigmoidoscope, the doctor will usually give a preliminary report. Depending on what your doctor finds, a complete colonoscopy may be recommended. A colonoscopy is a similar procedure using a flexible instrument that goes further into your colon than the sigmoidoscope. With this procedure, your entire colon can be examined, and polyps or other small growths can be removed for a biopsy. It may take 1 to 2 weeks for results of a biopsy.

Call Your Doctor If Any of the Following Occurs

  • Bleeding from your rectum; notify your doctor if you pass a teaspoonful or more of blood
  • Black, tarry stools
  • Severe abdominal pain
  • Hard, swollen abdomen
  • Signs of infection, including fever or chills
  • Nausea
  • Inability to pass gas or stool


American Gastroenterological Association

National Digestive Diseases Information Clearinghouse


Health Canada

Canadian Institute for Health Information (CIHI)


American Cancer Society website. Available at: http://www.cancer.org/docroot/home/index.asp .

American Gastroenterological Association website. Available at: http://www.gastro.org .

National Digestive Diseases Information Clearinghouse website. Available at: http://digestive.niddk.nih.gov .

Last reviewed November 2007 by Daus Mahnke, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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