Medical tests for babies
9-minute read
Key facts
- Medical tests can help your doctor understand your baby’s health and plan the right care.
- Tests may be done soon after birth, during an emergency or to find out what’s causing symptoms.
- Your baby might need a test to find out why they have a fever, trouble breathing or other signs of illness.
- Common tests include blood, urine or stool tests and scans, such as x-rays and ultrasounds.
- Your doctor will explain what the test is for and how it works.
Why might my baby need a test?
There are different reasons why your baby might need a medical test. Tests help doctors find out what’s going on with your baby’s health and make sure they get the right treatment.
Your baby might need a test to:
- check for a serious health condition early — such as during a newborn bloodspot screening test
- look for a health problem in an emergency — for example, after an injury
- find out what’s causing symptoms — such as fever, vomiting or trouble breathing
- plan treatment — if your baby is feeling unwell or not getting better
What tests might my baby need?
Common tests include:
- blood tests
- urine tests
- stool tests
- x-rays
- ultrasounds
- CT scans
- MRI scans
- lumbar punctures
To choose the right test, your doctor will think about:
- what the test can show
- any possible risks or side effects
- your baby’s comfort and safety during the test
If you're unsure, ask your doctor to explain why the test is needed and how it works.
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Blood test
A blood test can give important information about your baby’s health.
What happens before the test?
A healthcare professional will ask for your baby’s name and check their birth details. They will explain if they will take blood from a:
- vein
- finger prick
- heel prick
What happens during the test?
You may help gently hold your baby still. They may warm the area or use a light to help find a vein. A small amount of blood is taken using a fine needle.
What happens after the test?
The blood sample is sent to a laboratory. You may be told to wait in the clinic a little longer or go home. Your doctor will get the results and explain what they mean for your baby’s health.
Urine test
A urine test may be done if your baby has symptoms, such as:
What happens before the test?
Your doctor will explain how to collect the urine sample. The way it’s done depends on your child’s age.
What happens during the test?
Children may wee into a sterile cup. Babies or toddlers who wear nappies may need a:
- small urine collection bag placed on their skin
- clean catch, where you catch wee in a cup
- urine catheter (a soft, thin tube) to collect urine from the bladder
What happens after the test?
The sample is tested soon after collection. Sometimes it’s sent to a laboratory. You may be told to wait in the clinic for a few minutes or go home. Your doctor will get the results and explain what they mean for your baby’s health.
Stool test
A stool test checks your baby’s poo for bacteria, viruses or parasites. It can also help find bowel conditions.
What happens before the test?
A healthcare professional will explain how the sample needs to be collected. You may be asked to collect the sample yourself or a healthcare professional might do it for you.
What happens during the test?
After your baby does a poo:
- if your baby wears a nappy, it will need to be opened on a clean surface
- a clean tool is used to collect a small amount of poo
- the sample is placed in a small tube and sealed
What happens after the test?
The sample needs to be kept cool and will be sent to the laboratory. Your doctor will get the results and explain what they mean for your baby’s health.
X-ray
An x-ray is a quick and painless test that takes pictures of your baby’s bones or other body structures.
What happens before the test?
The doctor or radiographer will explain what will happen and help your child feel calm. You may support your child during the test.
What happens during the test?
Your child will be asked to lie, sit or stand still for the picture. Sometimes, they may be asked to hold their breath for a few seconds.
What happens after the test?
Your child can return to normal activities unless told otherwise. Your doctor will check the images and explain the results.
Ultrasound
An ultrasound may be done to look at soft tissues and organs inside your baby’s body. It’s often used to check the lungs, heart or abdomen (belly).
What happens before the test?
Your doctor will explain why the test is needed and if you need to do anything to prepare.
What happens during the test?
During the scan:
- your child will be asked to lie down or sit still
- a gel may be placed on their skin
- the ultrasound probe is gently moved over the area
What happens after the test?
The gel is wiped off and your child can get dressed. Your doctor will review and explain the test results.
CT scan
A CT scan uses x-rays to take clear pictures inside your baby’s body.
What happens before the test?
Before the scan, you will be given instructions — this is a good time to ask any questions.
Your baby might need a small plastic tube in a vein (IV) for contrast dye to make certain areas show up better. Numbing cream may be used to make this more comfortable.
You may be asked to keep your baby awake before the scan so they sleep naturally during it.
What happens during the test?
Your baby will need to lie still during the scan. Special cushions may be used to keep your child safe and comfortable. Toys, blankets or music may help keep your baby calm. You may stay in the room with your child unless told otherwise.
What happens after the test?
If contrast dye was used, your baby may need to drink extra fluids after the scan to help flush it out. Your doctor will review the results and explain them.
MRI scan
An MRI scan uses magnets and radio waves to take detailed pictures inside your baby’s body. It helps check soft tissues, such as the brain or muscles.
What happens before the test?
Before the scan, you will be given instructions and may ask questions.
Your baby might need a small plastic tube in a vein (IV). Your baby may need sedation if the scan takes a long time. Your healthcare professional will explain this to you.
What happens during the test?
Your baby lies on a narrow bed that moves into the MRI machine. It can be loud, so earplugs or headphones may be used. Toys, videos or music may help keep your baby calm. You may stay in the room with your child unless told otherwise.
What happens after the test?
If sedation was used, your child will be checked until they’re fully awake. Your doctor will review and explain the results.
Lumbar puncture
A lumbar puncture takes a small amount of fluid (cerebrospinal fluid) from the lower back. This is done to check for infections or health problems in your baby’s brain or spinal cord.
What happens before the test?
Your doctor will explain the test, including risks and steps. Numbing cream or pain relief may help keep your baby comfortable.
What happens during the test?
Your child may lie on their side or sit up with their back gently curved. A thin needle is used to collect the fluid.
What happens after the test?
The area is covered with a small dressing after the test. Your healthcare professional will explain if your child needs to rest in bed or may go back to normal activities.
The sample is sent to a laboratory. Your doctor will review the results and explain them.
Questions to ask your doctor
You may have questions before your baby has a test. Understanding what to expect can help you feel more confident and prepared.
Here are some questions you may want to ask your doctor.
- Why does my baby need this test?
- Does my baby need to do anything to prepare before the test?
- What happens during the test — will it hurt my baby?
- How can I help my baby cope with having this test?
- How long will it take to get the results?
- Are there any side effects or risks?
- Can my baby go back to normal activities afterwards?
ASK YOUR DOCTOR — Preparing for an appointment? Use the Question Builder for general tips on what to ask your GP or specialist.
Resources and support
The Royal Children’s Hospital Melbourne has more information about:
Sydney Children’s Hospitals Network offers information about:
Inside Radiology explains what to expect during your child’s MRI scan.
Speak to a maternal child health nurse
Call Pregnancy, Birth and Baby to speak to a maternal child health nurse on 1800 882 436 or video call. Available 7am to midnight (AET), 7 days a week.
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Last reviewed: March 2025
