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What Is A Sigmoidoscopy?

This Endoscopy Procedure Examines The Last Section Of The Large Intestine


Updated July 09, 2014


Colonoscopy examines the entire length of the colon; sigmoidoscopy examines the lower third

Photo © A.D.A.M.

What Is A Sigmoidoscopy?

A sigmoidoscopy is a way for a doctor to examine the last one third of the large intestine, which includes the rectum and sigmoid colon. A flexible viewing tube with a lens and light source on the end, called a sigmoidoscope, is used. Looking through the eyepiece at the other end of the scope, the doctor can see the inside of the colon.

In this test, the doctor can check for cancer, abnormal growths (polyps) and ulcers. It is usually performed in the doctor's office, and can take 15-30 minutes.

What Is A Sigmoidoscopy Used For?

Beginning at age 50, a sigmoidoscopy is usually performed every 3 to 5 years to screen for colorectal cancer. In people who are at a higher risk for colorectal cancer due to ulcerative colitis, family history of colorectal cancer, or familial polyposis, screening may be recommended starting at age 35.

A sigmoidoscopy may also be used as a follow-up procedure after a digital rectal exam is abnormal, or after a positive fecal occult blood test. It can also help identify the source of some types of rectal bleeding or other problems in the lower digestive tract. A biopsy may be taken during the procedure, if the doctor deems it necessary. If an abnormality is found in a sigmoidoscopy, a colonoscopy may be recommended.

What Is The Preparation For A Sigmoidoscopy?

In order for the doctor to get a clear view of the intestinal wall, the colon must be fairly empty. The doctor will give you specific instructions on how to prepare for the test, which may include laxatives or enemas. On the day of the test, your diet should consist mainly of liquids, rather than solid food.

How Is A Sigmoidoscopy Done?

You may be asked to wear a hospital gown, or to remove your clothes from the waist down. An assistant may record temperature, pulse, blood pressure, and respiratory rate. You will be instructed to lie on your left side on the exam table, with one or both knees raised to your chest. The doctor will insert the sigmoidoscope into your rectum and pump air through the sigmoidoscope if necessary for a clearer view. A biopsy may be taken using a device on the end of the sigmoidoscope.

What Are The Risks Of A Sigmoidoscopy?

Injury to the bowel is a rare complication of this procedure.

Is A Follow-Up Appointment Necessary?

If a biopsy was taken, your doctor should have the results in a few days. A normal diet and schedule can be resumed immediately after the test.

When Should I Call The Doctor?

Call your doctor immediately if you experience:

  • Rectal bleeding
  • Feeling faint
  • Short of breath
  • Palpitations

Call your doctor if you experience:

  • nausea
  • vomiting
  • cramps
  • abdominal pain
  • fever
  • chills
  • severe headache
  • muscle aches

Anything Else I Should Know?

A sigmoidoscopy is limited to screening the lower one third of the bowel. A colonoscope is necessary to screen for cancer higher in the bowel.

Back to Diagnostic Tests Index

Related Video
See What to Expect at a Colonoscopy

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