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When Your Child Needs a Colonoscopy or Sigmoidoscopy

A colonoscopy (also called a lower endoscopy) is a test that allows the doctor to look inside the colon and rectum. A sigmoidoscopy is a shorter version of this test that only includes the sigmoid colon (lower part of the colon) and rectum. The doctor may perform a biopsy (take tissue samples), and check for polyps (tissue growths) or bleeding. A colonoscopy takes about 60 minutes. A sigmoidoscopy takes about 30 minutes.

Image of the small intestine, colon, and rectum with a colonoscope


Image showing the rectum and sigmoid colon with a sigmoidoscope

Before the Test

Your child’s colon may need to be cleaned out before the test. Follow any instructions given by the doctor. These may include:

  • Have your child drink a liquid bowel prep before the test.

  • Switch your child to a clear liquid diet 1–2 days before the test.

  • Give your child a laxative, a suppository, or enema the night before and on the day of the test.

  • Don’t give your child anything to eat or drink 4–6 hours before the test.


Let the Doctor Know

For your child’s safety, let the doctor know if your child:

  • Is allergic to any medication, sedative, or anesthesia.

  • Is taking any medications, especially aspirin.

  • Has heart or lung problems.

During the test

A colonoscopy or sigmoidoscopy is done by a doctor in an office, testing center, or hospital.

  • You can stay with your child in the testing room until your child falls asleep or the test begins.

  • Image of a child in bed with two health care workers nearby performing a colonoscopy Your child lies on an exam table on his or her side.

  • Your child is given a pain reliever and a sedative (medication that makes your child relax or sleep). This is done through an intravenous (IV) line. Or, your child is given anesthesia (medication that makes your child sleep) by facemask or IV. A trained nurse or anesthesiologist helps with this process and also monitors your child. Special equipment is used to check your child’s heart rate, blood pressure, and blood oxygen levels. Sigmoidoscopy usually doesn’t require your child to be sedated.

  • The doctor inserts a colonoscope or sigmoidoscope into your child’s rectum and colon. This is a long, flexible tube with a camera and a light at the end. During a sigmoidoscopy, the scope will only advance through the sigmoid colon.

  • Air is pushed through the scope to expand your child’s lower GI tract. Water may also be used to clean the colon.

  • Images of your child’s colon are viewed on a screen as the scope advances.

  • The doctor may take tissue samples and remove any polyps that are found.

After the test

  • If a sedative or anesthesia was given, your child is taken to a recovery room. It may take 1 to 2 hours for the medication to wear off.

  • Unless told not to, your child can return to his or her normal routine and diet right away.

  • The doctor may discuss early results with you after the test. You’re given complete results when they’re ready.

Helping your child prepare

You can help your child by preparing him or her in advance. How you do this depends on your child’s needs.

  • Explain that the doctor will be testing the colon and rectum. Use brief and simple terms to describe the test. Younger children have shorter attention spans, so do this shortly before the test. Older children can be given more time to understand the test in advance. 

  • As best you can, describe how the test will feel. An IV may be inserted into the arm to give medications. This may cause a brief sting. Your child won’t feel anything once the medications take effect.

  • Allow your child to ask questions.

  • Use play when helpful. This can involve role-playing with a child’s favorite toy or object. It may help older children to see pictures of what happens during the test. 

Call the doctor if your child:

  • Has a large amount of blood in the stool right after the test or blood in the stool for several days

  • Has a persistent fever over 100.4°F (38.0°C)

  • Has abdominal pain



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