Colon Transit Study Factsheet
Introduction
A colon transit study looks at the shape of the large intestine and how quickly food moves through it. The large intestine is part of the digestive system.
The digestive system is a group of organs that break down the food we eat, absorbing nutrients and turning them into waste.
The colon is the largest part of the large intestine. It removes water and nutrients from liquid waste and turns it into poo.
The colon transit study uses:
- a Gamma camera - a large camera that measures radiation
- radiotracer – an injection of radioactive fluid that moves through the body.
The gamma camera takes pictures of the radiotracer moving through your child’s digestive system.
A colon transit study is used to check children who have chronic or ongoing constipation. Constipation is when you have very hard poos that are difficult to pass.
Before the scan
To make sure the scan results are correct., your child must not be given laxatives or enema:
- for three days before the scans
- during the five days of the scans
A laxative is a medication that helps your child poo.
An enema is a liquid put in your child’s bottom to help empty their colon.
Speak to your local doctor if you have concerns about the expected side effects of stopping laxatives and enemas before or during the scan.
Your child can eat and drink normally before the scan.
During the scan
The scan is done over five days; your child can eat and drink normally.
Your child will not feel anything during the scan, and the camera will not touch them.
Your child will be weighed to help calculate the correct amount of radiotracer.
You can stay with your child while the images are being taken.
Over the five days, you need to write down any time your child does a poo.
Day 1 scan
On the first morning, your child will be asked to drink milk mixed with a small amount of radiotracer. The radiotracer should not change the taste or texture of the milk.
You can then leave the department, and your child’s treatment team will give you a time to come back for the scan. This should be about six hours.
When your child returns to the department, they will do the first scan. Generally, the steps are:
- your child lies on the scanning bed
- velcro straps may be used to gently help your child stay still
- the gamma camera takes images of your child’s digestive system, showing how well the liquid has passed through. This should take about ten minutes.
Days 2 to 5: follow up scans
Your child will have the same 10-minute scan done on the mornings of days 2, 3, 4 and 5 to check for changes.
After the scan
You can leave once the images are checked by a doctor or nuclear medicine scientist each day.
The final results will be sent to your child’s doctor within a couple of days after the last scan. You will need to schedule a follow-up appointment with your child’s doctor to discuss the results.
Management
Radiation
Your child will be exposed to a small amount of radiation during the scan. The benefits of finding and treating kidney problems are greater than the small risk of this low dose.
Allergic reactions
Allergic reactions to radiotracer are very rare and usually mild. Your child’s doctor will talk to you about any potential risks before the scan. Let your child’s treatment team know if they have any allergies.
Supporting your child during the scan
Scans can be uncomfortable for children. You can prepare your child by:
- explaining to them why the test is needed in simple words
- bringing along their favourite comfort objects, like a blanket, toy, or dummy
- arriving 30 minutes before the appointment if your child needs numbing cream.
