Anorectal manometry

Anorectal manometry is a test to measure how well the muscles and nerves in the rectum and anus in your child’s bottom are working. Your child needs this test so that the doctors can check how well the muscles and nerves are working to push out faeces (poo).

What happens before the test?

You will already have received information about how to prepare your child for the test in your admission letter. The doctors will explain about the test in more detail, discuss any worries you may have and ask you to sign a consent form giving permission for your child to have the test.

If your child has any medical problems, particularly allergies, please tell the doctors about these. Please also bring in any medicines your child is currently taking and show these to the doctor.

This investigation can be done while your child is awake or under an anaesthetic. This will be assessed by the pre-admission nurse in conjunction with medical staff and then they will explain to you what they think is most appropriate.

About two hours before the test is due to start, your child will be given an enema – a liquid medicine will be flushed into their bottom and rectum so that it is empty of faeces (poo) for the test. If your child is having a colonoscopy on the same day then this test will be performed under anaesthetic with the colonoscopy, so your child may not require an enema as they will have had bowel preparation already for the colonoscopy. If they are having the test under anaesthetic, a thin tube (cannula) will be put into a vein in their arm.

What does the test involve?

You and your child will be taken to the Gastroenterology Investigation Suite where the test is done. A nurse will stay with your child throughout. The doctor will insert a catheter (flexible plastic tube) into your child’s bottom and pass it up into the rectum – the other end is attached to a machine which measures how well the muscles and nerves are working. A small balloon on the end of the catheter is then inflated gradually, which mimics poo in the rectum. The machine will record the reaction of the nerves and muscles in your child’s rectum and anus when this happens.

What happens afterwards?

After the test, the doctor will deflate the balloon and remove the catheter so that your child can return to the ward. Once your child is awake and able to sit up on their own, they will be able to eat and drink. Unless your child vomits (is sick), once they have eaten something and passed urine, and providing no other tests are planned, the cannula will be removed and you will be able to go home.

Are there any risks of the test or side effects of the sedative medicine?

There is a very small risk that the catheter could damage your child’s anus and rectum. However, this is very unlikely as the catheter is flexible and the doctors and nurses who do the test are very experienced.

If your child is having an anaesthetic for this test, their sleep pattern may be altered for up to 48 hours after the test. The time it takes to recover from an anaesthetic varies from child to child – encourage your child to rest if they are still sleepy the following day.

As your child had nothing to eat or drink for some time before this test, there is a small chance that they may be mildly dehydrated afterwards. Symptoms of dehydration include dry lips, pale skin, sunken eyes and not passing urine.

While on the ward, and when you get home, it is important to encourage them to drink as frequently as possible. This will also help to reduce the effects of the anaesthetic.

It may be sensible to keep your child off school for a day following the test to allow them time to recover.

Keep a close watch on your child until you feel happy that they are fully recovered and do not leave them alone. Contact the staff in the Gastroenterology Investigation Suite if you are worried.

How long will it take to get the results?

Your child’s test results will be given to you at your next outpatient appointment at the hospital. However, if there is a need to start on new treatment before the appointment, the hospital will contact both you and your family doctor (GP) with details.

When you go home

You should call your GP or your local hospital if your child:

  • becomes generally unwell

  • refuses to eat or drink

  • is sick

  • is unusually sleepy or it is difficult to wake them up

Compiled by: 
The Gastroenterology Investigation Suite staff in collaboration with the Child and Family Information Group This information does not constitute health or medical advice and will not necessarily reflect treatment at other hospitals.
Last review date: 
July 2013


Please note this is a generic GOSH information sheet. If you have specific questions about how this relates to your child, please ask your doctor. Please note this information may not necessarily reflect treatment at other hospitals.