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.

We recommend metabolic screening for all newborns

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

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

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

When screening is complete, 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.

Immediate family members can also request the blood spot cards of a person that has died by completing this form.

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  • 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.

  • 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.

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)

Health New Zealand

Provides fact sheets on the disorders screened in the New Zealand programme. It includes descriptions of each disorder and how they can be detected and treated.

Newborn Screening Info

Contains fact sheets about disorders commonly screened for by newborn screening. Because it is an overseas site, not all information will be relevant to Aotearoa. For example, some disorders mentioned are not currently screened for in Aotearoa.

New Zealand Organisation for Rare Disorders

Rare Disorders NZ provides New Zealand's central starting point for information about rare disorders. They can refer you to support groups for specific disorders.

Cystic Fibrosis NZ

The Cystic Fibrosis NZ website provides information about cystic fibrosis. You can also find out about community support leads, and support groups.

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