The colon (large bowel) is part of the digestive system, which carries food through the body after it is eaten. The colon is where stool (poo) is formed, stored, and eliminated. The colon contracts rhythmically to push the food and waste along.

The muscles and nerves of the colon need to work together to produce these contractions. These movements are referred to as colonic motility. Motility may be measured using a technique called colonic manometry. This technique records the pressure waves when the colon contracts.

What is a colonic manometry study?

In some cases, the contractions of the colon may be changed or absent. This may lead to problems, such as constipation or soiling. Colonic manometry aims to measure these contractions. It gives us an understanding of how the muscles and nerves of the colon are working together.

Colonic manometry requires:

• home preparation before the test
• a general anaesthetic
• colonoscopy to place the manometry tube
• performing the test once your child has recovered from their general anaesthetic

How is colonic manometry performed?

To perform colonic manometry, a thin, flexible tube (catheter) is placed into your child’s colon. The tube is filled with water, which drips out of small holes along the side of the tube. A machine measures the changes in pressure of the water leaving the tube. This provides a picture of the patterns of contraction and relaxation along the colon.

To place the manometry tube, your child will require a colonoscopy. This is a procedure where a gastroenterologist (a doctor specialising in the digestive system) looks at the inside of the colon.

The colonoscopy is done with a long, flexible tube with a camera on the end, called a colonoscope. The colonoscope is inserted into the anus (bottom) and slowly pushed into the colon. The colon is examined and biopsies (small samples of bowel) may be taken. Your child will be under a general anaesthetic for the placement of the manometry tube.

For more information, see our fact sheet Endoscopy – Colonoscopy.

Preparing for colonic manometry

• Your child’s bowel must be clean before their colonoscopy. This allows the doctor performing the colonoscopy to see inside the colon.
• Special preparation is required but may be different for each patient. Details regarding your child’s bowel preparation will be discussed with you in the lead up to the procedure.
• For more information regarding bowel preparation, please see our fact sheet Endoscopy – Colonoscopy.

What to expect on the day of colonic manometry

• Your child may continue clear fluids (water, clear apple juice) until the time of their admission.
• Your child will require a general anaesthetic for their colonoscopy. This involves a medicine being given through a drip into a vein (intravenous or IV therapy). An anaesthetic doctor will meet with you and your child before their procedure.
• You will be able to stay with your child until right before their procedure, when they go to sleep in the anaesthetic bay.
• After the colonoscopy, your child will be taken to a recovery bed. You will be able to join them when they wake up.

Performing the manometry study

• Once your child has recovered from their general anaesthetic, the colonic manometry study will be started.
• An x-ray will be taken of your child’s tummy to check the position of the tube.
• The manometry tube will be connected to a machine, which measures the changes in pressure inside the colon.
• The study will measure the response of your child’s colon to different stimuli. These include eating a meal and taking medication (bisacodyl), which may make the colon contract.
• Your child will need to remain in bed during the procedure. Please bring any activities they enjoy, such as books, games, and videos.
• After the study, a doctor or nurse will remove the tube from the bottom. Your child will be awake during the removal. The removal may be uncomfortable but is not usually painful.
• The study will take approximately four to six hours to complete.

After the manometry study

Provided your child is feeling well, eating and drinking normally, and no further tests are planned for their admission, you will be able to head home in the evening after the test.

The results will be discussed with you and your child at their next outpatient appointment.

Your child may have one or more of the following side effects. These usually get better without special treatment.

• Bleeding: a small amount of blood may be seen in the poo. This is usually caused by bleeding from the lining of the bowel from where biopsies were taken, or where the tube was clipped to the inside of the bowel.
• Nausea or vomiting: if your child feels sick, stop them from eating and drinking for half an hour. After this, they may start having sips of clear fluids. Slowly increase what they eat and drink.
• Abdominal pain and bloating: if the pain is mild, your child should rest and have sips of clear fluids until they are feeling better.

When to seek medical assistance

Call the hospital if your child has:

• vomited more than three times over an eight-hour period
• a vomit or bowel action with more than three to five mililitres (one teaspoon) of bright red blood
• severe tummy pain or bloating
• a high temperature (above 38ºC)
• difficulty swallowing

Key points to remember

• The full amount of bowel washout preparation must be taken, as your child’s bowel needs to be completely empty for a colonoscopy.
• Your child can usually go home in the evening after the study.
• Contact the hospital if your child is unwell after the colonoscopy and manometry.

For more information

• Kids Health Info fact sheet: Endoscopy – Colonoscopy
• The Royal Children’s Hospital Department of Anaesthesia and Pain Management: Parent Information
• Talk to your GP, gastroenterologist or paediatric surgeon.

Developed by Departments of Gastroenterology and Paediatric Surgery at The Royal Children's Hospital, Melbourne. We acknowledge the input of RCH consumers and carers.

Reviewed June 2020.

Kids Health Info is supported by The Royal Children’s Hospital Foundation. To donate, visit www.rchfoundation.org.au