Colonic manometry

Manometry is a way of measuring how well the muscles and nerves in the digestive system are working. Colonic manometry looks at the muscles and nerves in the colon (large intestine). This page from Great Ormond Street Hospital (GOSH) explains about the colonic manometry test and what to expect when your child has one. The digestive system is a hollow tube from the mouth to the anus. The walls of the tube contain muscles and nerves that squeeze food rhythmically through the system – this action is called peristalsis. If the muscles and/or nerves are not working properly, food cannot pass through the digestive system.

You will need to come to the ward a few days before the test so that your child can have some bowel cleansing medicine to clear their large intestine. The pre-admission nurse may also ask you to increase medications at home before admission to hospital.

If your child normally uses a trans anal irrigation system such as Peristeen®, or has an antegrade colonic enema (ACE), please bring the equipment with you to hospital, as it can be used to help clean your child’s bowel.

Your child will need to follow a special diet during the days that the medicine is being taken. We will give you a diet sheet.

The person bringing your child to the test should have ‘Parental Responsibility’ for them. Parental Responsibility refers to the individual who has legal rights, responsibilities, duties, power and authority to make decisions for a child. If the person bringing your child does not have Parental Responsibility, we may have to cancel the test.

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.

At the start of the hospital admission, the nurse will put a thin tube (cannula) into a vein in your child’s arm. A nurse will apply some local anaesthetic cream first so that the skin is numb. Your child may like to have a cold numbing spray before the needle instead of the cream. Some blood tests will be done during your child’s hospital stay to measure the salts and minerals in their blood.

As the catheter used in colonic manometry is inserted while your child is under general anaesthetic, they will have to stop eating and drinking for a few hours beforehand. We will tell you the night before the procedure of the time that your child should be ‘nil by mouth’ – in other words, have nothing to eat or drink before the anaesthetic.

It is equally important to keep giving your child drinks until those times to ensure they remain well hydrated. We recommend waking your child in the night to give them a drink.

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

You and your child will be taken to the Gastroenterology Investigation Suite where the test will take place. A nurse will stay with your child throughout.

While your child is under general anaesthetic, the doctor will carry out a colonoscopy – that is, they will use an endoscope (a long flexible camera with a light on the end) to insert a catheter (flexible, plastic tube) into your child’s large intestine via their bottom. Once the catheter is in the correct place, very small metal clips are used inside to keep it in place and the end outside your child is taped to your child’s buttock.

When your child has fully recovered from the anaesthetic, the end of the catheter is attached to a machine which measures how well the muscles and nerves are working. During the test an x-ray will be taken of your child’s tummy to confirm the position of the catheter. Your child will be given a meal as part of the test.

About an hour later, a medicine (laxative) will be put into the catheter to stimulate the large bowel and test how it contracts (squeezes). A second dose of this medicine will be given approximately one hour after this. The test could take up to five hours but your child will be able to watch DVDs, play with a tablet or phone, or read during the test.

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

After the test, the doctor or nurse will remove the catheter from your child’s bottom and your child will come back to the ward. Once your child has eaten something and have passed urine, and as long as no other tests are planned and there are no complications, the cannula will be removed and they will be able to go home.

After a general anaesthetic, most children recover quickly and are soon back to their usual activities. Some children may get side effects – however, these are usually mild. Headaches, nausea (feeling sick, sometimes with vomiting) and a sore throat are common but can usually be treated effectively with medicines.

Other side effects generally just need time to wear off and include tiredness, dizziness. Some children may also have disturbed sleep patterns for a few days afterwards.

Your child may have some tummy pain due to either the air used to inflate the intestine during the endoscopy or from the laxative given during the procedure – this can be helped by encouraging your child to walk around, gently rubbing their tummy or having a warm bath. They may also need to use the toilet urgently.

There may be blood spots from the bottom if biopsies (small samples of tissue) were taken from the intestinal wall or from the removal of the clips securing the catheter.

The nurse will tell you if a clip was unable to be removed inside the bowel during the procedure. If this happens, most are passed out in your child’s poo in about three to five days. You probably will not see the clip if it passes and you do not need to keep the clip, just flush it away with your child’s poo. However, if your child is due to have a Magnetic Resonance Imaging (MRI) scan, please tell them this during the metal check beforehand.

Unless you have been advised otherwise, your child can start eating and drinking their usual diet and re-start any medications that were stopped for the test.

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.

Your child’s test results will be given to you at your next outpatient appointment at the hospital. The analysis of this test is complicated so may take some time to get the results. 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.