Te whakamātau poka rekereke — he whakamātau i te whakarau pūngao o te pēpi hou Heel prick test — newborn metabolic screening
This test — also known as the Guthrie test and newborn blood spot screening — screens for rare but serious disorders in your pēpi (baby). It is done by taking a blood sample from their heel at or as soon as possible after 24 hours of age. If a disorder is found, early treatment can prevent permanent damage or death.
On this page
- We recommend newborn metabolic screening for all newborns
- About the heel prick test
- Before the sample is taken
- How the heel prick is done — taking the blood sample
- Screen results
- If your pēpi has a disorder
- The blood spot card after the screen
- Use of leftover blood spots
- DNA
- Safeguards for the newborn metabolic screening programme
About the heel prick test
The heel prick test is when a blood sample is taken from your baby's heel. Four small blood drops are collected on a special card. The blood is then:
- sent to a screening lab
- tested for certain disorders that are difficult to identify without a blood test.
Screening can find these disorders before symptoms appear. This means you can get early treatment for your pēpi. If your baby's screen shows an increased risk of a disorder, they will need a diagnostic test to confirm if they have a disorder.
Disorders screened for in the heel prick test (internal link)
[Music playing]
These babies all look healthy and well.
Most babies in New Zealand are born healthy,
develop well, and grow into strong and healthy children.
However, there are some rare and very serious
disorders that can affect the health and well-being of babies
and young children.
Doctors and midwives cannot detect some of these disorders
when they examine babies, but they can be identified
if the baby's blood is tested in a laboratory.
New Zealand and many other countries
routinely screens newborn babies using a heel prick blood test.
With the parents' consent, a small sample of blood
is taken from the baby when they're 48 hours old
and screened for these rare, but serious, disorders.
The heel prick test is not compulsory, but over 99%
of babies born in New Zealand have the test.
That's around 60,000 babies a year.
Each year screening identifies around 40 newborns
with specific disorders that need immediate treatment.
This treatment could involve special diets for the growing
child, or the baby being given medicine.
Even though these disorders are rare,
for the 40 babies a year who are identified through the program,
if treatment is not started when the baby is very small,
their health and well-being can be very seriously affected.
Without early treatment permanent damage
to the child's health occurs, and the growing child
could become disabled or have a less chance of living
to be a healthy adult.
During your pregnancy your lead maternity carer
will discuss the heel prick test with you.
How you doing?
Counting down the days.
Not long to go now.
Just come to talk about the heel prick
that we do at 48 hours, or as soon as possible afterwards.
That's great.
Is that all right?
Let's sit.
Thanks.
I'm just going to talk about the heel prick.
And we do that in the hospital, or if you're at home
I'll do it in your home.
OK.
Now we just need some blood from baby's heel.
They're not that impressed about it,
but it's only a small amount that we take and it's
quite quick.
It goes to Auckland to the National Testing Center.
Now have you got any questions?
So what are they actually testing for?
They're testing for over 20 metabolic disorders.
I'll give a handout to read that will
explain about the disorders that we're testing for.
Within six hours of baby's birth,
you'll lead maternity carer will discuss the heel prick
test with you again.
Congratulations on your lovely girl.
Thank you.
And you're happy with us doing that heel prick?
Yes.
Great.
So you know that's to be done 48 hours after baby is born?
It's a little pin prick, so it will
be-- she won't be that impressed about having it done,
but it's very quick.
Won't hurt her?
Only for a really short time.
OK.
When baby's 48 hours old, or as soon as possible thereafter,
the lead maternity carer completes the heal prick test.
[MUSIC PLAYING]
OK.
[MUSIC PLAYING]
[BABY WHIMPERS]
Sometimes it can be a little more difficult to obtain
the baby's blood sample, and the lead maternity carer
may need to prick the baby's heel again to get enough blood.
[MUSIC PLAYING]
It's stopped bleeding now, so just put that pressure on there
so it's good [INAUDIBLE].
She wasn't too upset.
No, she wasn't too upset.
All right.
Really just squealed a bit [INAUDIBLE].
[MUSIC PLAYING]
The specimen is sent here to the National Testing
Center for testing.
Thanks to the Starship Foundation,
we now have the tandem mass spectrometer
on which we test for 20 plus disorders
on a single spot of blood.
This is one of the many ways that we
test blood for too little or too much of the components
or the [INAUDIBLE] enzymes which can be indicative of one
of these disorders.
[MUSIC PLAYING]
For most families providing the blood sample
is the end of the heel prick test.
Hi, Karen.
How you doing?
We're doing good, thanks.
And how's the feeding going?
Well, it's going much better than the last time.
If you do not hear anything about the test
from your lead maternity carer, your baby
did not test positive for the disorders that are tested for.
Sometimes your lead maternity carer
could ask if they could do a second test.
This second test is needed in about 1 in 100 babies.
In many cases the second test is done
because there was a problem with the way the first sample was
taken or processed.
If the testing does show that your baby has a health problem,
then your lead maternity carer and your doctor
will contact you to discuss the disorder and the next steps.
OK.
Everything is looking good, so we will say you and [? Kyata ?]
next Tuesday.
If you need anything in the meantime, just give us a call.
Will do.
Thank you.
OK.
See you later, [? Kyata. ?]
Thanks, Chris.
OK.
See you later.
Before the sample is taken
Your lead maternity carer (LMC) or midwife will talk to you about the screening test and give you the opportunity to ask questions. They will also give you a brochure that has information about the Newborn Metabolic Screening Programme. The information given to you will include:
- discussion about the screening test
- storage of the card
- possible future uses and the option of return
- results
- follow-up processes.
Once your LMC or hospital midwife has your consent, they or a trained blood taker (phlebotomist) will take the sample. This can be done in the hospital, or at home.
How the heel prick is done — taking the blood sample
The blood sample is taken when your pēpi is 24 hours old, or as soon as possible after this, but it should be taken before they are 72 hours old.
A blood sample is taken from your baby's heel using a device called a lancet. This makes a small puncture on the side of their heel. You can prepare your pēpi for the sample to be taken by putting booties on them, or wrapping their feet well. This makes sure that your baby's heel is warm, and it is easier and quicker to take the blood sample.
Having a heel prick might cause your baby some discomfort. You can reduce your baby’s discomfort by feeding or cuddling your baby while the blood sample is being taken. Your LMC or midwife can talk to you about other ways of keeping your baby comfortable while the blood sample is taken.
A blood spot card collects the sample. After the test, you can apply gentle pressure to the heel using cotton wool to stop the bleeding. Your midwife will send the card to the lab for testing.
Why the screen is done at 24 hours
When a baby with one of the screened for disorders is in the womb, the placenta clears away any abnormal biochemical levels as the baby’s system produces them.
When the baby is born, the baby’s own system takes over and if the baby has a disorder, the biochemicals can accumulate to toxic levels or cause other problems.
The baby’s own system should be working properly at 24 hours of age, so this is the best time to do the screen — when your baby’s system is working independently, and before your baby gets sick.
Screen results
If the screen results are normal you will hear from your LMC or midwife within 10 days of screening.
Repeat samples
Your pēpi may need another heel prick or blood spot collection if:
- there was too much or not enough blood in the sample
- the blood sample was contaminated, for example with baby powder or lotion
- it took too long to reach the lab, which can make the result inaccurate
- results are borderline (slightly abnormal).
If this happens your LMC or midwife will contact you and ask to take another sample. It is important that the new sample is taken as soon as possible so that your baby completes screening.
If the screen result is abnormal
If the screen result is abnormal and suggests a probable disorder, the lab will call your LMC or midwife as soon as possible. Your midwife will explain the result and next steps.
Your midwife will arrange for an assessment and diagnostic testing with a paediatrician. The paediatrician will confirm whether they have a disorder.
Not all babies with an abnormal screen result will be found to have a screened disorder. Other possible reasons for an abnormal result can include being born premature.
If your pēpi has a disorder
If diagnostic testing confirms your pēpi has a disorder, the paediatrician will:
- provide any urgent care your baby needs
- talk to you about what this means, including any ongoing treatment and management of the disorder your baby may need.
Treatment, either diet or medication, is best if started early, before the baby becomes sick, and can help your baby stay well and prevent severe disability or even death.
Disorders screened for in the heel prick test (internal link)
The blood spot card after the screen
After screening, the blood spot card will be stored forever in a secure locked area. Only authorised staff from the screening programme can access stored blood spots.
If you have requested it be returned, the lab will send it back to you.
Requesting the return of the screening sample
You can ask for your baby's blood spot card back after screening is complete or at any time in the future.
If you would like to request your baby's blood spot card, please download and complete the form below and send it to the laboratory. You will be sent the top part of your baby’s blood spot card with the specimen collection paper holding the blood sample.
- Return of newborn metabolic screening samples to family — request form [DOC, 98 KB]
- Return of newborn metabolic screening samples to family — request form [PDF, 149 KB]
Immediate family members can also request the blood spot cards of a person that has died by completing this form.
Use of leftover blood spots
When testing of the blood sample is completed blood samples may be used for the purposes below. These uses are rare, but they can help families, whānau, and the programme.
Sometimes the blood is retested, if the first result was unclear. Also, if a baby has a disorder but did not have a positive screening result, the blood sample can be tested again to see why this happened.
If a person dies for an unknown reason, a blood spot card can sometimes be tested to try and identify the cause. This is arranged by a doctor, with consent from family and whānau. This may provide valuable information for families and whānau about the cause of death. It can also provide families and whānau with information about the risk of that disorder in other family members.
If a baby has a condition which may have been caused during pregnancy, for example, CMV infection causing hearing impairment, the card can be tested to determine whether the infection was present at birth. This would be arranged by a healthcare professional with consent from the whānau.
Leftover blood spots may be used to monitor the screening programme for quality assurance purposes.
Screening is not 100% accurate and can give false negative and false positive results.
The Newborn Metabolic Screening Programme aims to keep screening results as accurate as possible by reducing the number of false positive and negative results. Leftover blood spot samples may be used to investigate the cause of false positive and negative results. This helps improve the accuracy of the screening.
Leftover blood spots may be used to make improvements to the programmes, for example, testing equipment for accuracy.
Very rarely, the New Zealand Police, usually with consent from family and whānau, request access to a specific blood spot card to identify a deceased or missing person. For instance, police may request a blood spot card to identify a body burnt in a house fire, or to identify victims of a natural disaster. Blood spots have also been used in criminal cases to identify victims.
The Ministry of Health and the New Zealand Police have a signed Memorandum of Understanding that regulates requests from the Police for access to blood samples and other information relating to them and clarifies the circumstances in which such requests may be granted.
The Code of Health and Disability Services Consumers’ Rights 1996 allows residual blood spots to be used for research that is approved by an ethics committee.
Any applications for population research must first be approved by an ethics committee and reviewed by the Newborn Metabolic Screening Programme Governance Team.
Residual blood spot samples stored before June 2011 also require individual written consent if requested for population research.
Blood spot cards and test results held by the Newborn Metabolic Screening Programme are the same as hospital records or medical files held by doctors in relation to the powers of the Court to order access or use the sample or information. In rare circumstances the Court can order access to blood spots for the purpose of testing.
DNA
Testing for some screened disorders involves looking for a common change (variant) in a section of DNA (gene). These variants are known to be associated with the disorder.
The testing is limited to only a small number of genes known to be linked to specific screened disorders.
No other genetic testing is done on samples unless first discussed and authorised by the parents, guardians, individual or through legal avenues, for example a court order.
Safeguards for the newborn metabolic screening programme
The laboratory which performs the screening for the programme must be International Accreditation New Zealand (IANZ) accredited against the international standard ISO 15189. This is the highest accreditation programme available. Accreditation by IANZ ensures the laboratory that carries out these tests is technically competent, has appropriate processes and is using up-to-date technology.
More information is available from the IANZ website.
International Accreditation New Zealand (IANZ) (external link)