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Neonatal screening test
5-minute read
All parents are offered the opportunity to have their baby screened for a number of rare disorders that are more easily treated if found early. The ‘newborn screening’ test is done in the first 48 to 72 hours after birth. You might also hear it called the ‘heel prick’ test.
Newborn screening tests are free. The tests are not compulsory and a verbal or written agreement (dependent on the state/territory) is required from the parents of the child before the heel prick test is performed.
An information pamphlet should be provided to you before collection of the sample, to allow discussion and to obtain your consent for collection and testing. Parents may refuse the test on behalf of their baby, but this could unnecessarily risk the baby’s health.
Most babies screened will not have any of the conditions but for the small number that do, the benefits of screening are enormous. Early treatment can improve their health and prevent severe disability or even death.
How is the test done?
If parents consent to screening, a midwife or nurse will perform the test by pricking your baby’s heel and putting a few drops of blood on a special filter paper.
The heel prick is not a comfortable procedure for your baby. The best thing you can do to ease the pain is comfort and hold them during the test. Breastfeeding has also been shown to soothe your baby. There are a number of other techniques you can use to reduce the pain your baby might experience.
The filter paper is allowed to dry and is then sent to the newborn screening laboratory where several different tests will be performed.
What is being screened for?
Newborn screening helps to identify a range of conditions, including:
- Phenylketonuria (PKU) — PKU is a rare condition that affects about 1 in 10,000 babies. A baby with this problem cannot properly use one of the building blocks of protein called phenylalanine, which accumulates in the blood and causes brain damage. This is a rare inherited condition that can cause severe learning difficulties. Early treatment with a special diet can prevent disability and allow babies to lead a normal life.
- Congenital hypothyroidism (CHT) — Hypothyroidism affects about 1 in 3,500 babies. It is caused by the thyroid gland not developing properly. Early treatment with daily thyroid hormone leads to normal mental and physical development.
- Cystic fibrosis (CF) — 1 in every 2,500 babies has cystic fibrosis. In cystic fibrosis, the mucus produced in the intestines and lungs is thicker than normal. This results in infections in the lungs. In the intestines, it may lead to difficulties with digesting food properly. The newborn screening test detects about 95% of babies with CF but also detects a few babies who are healthy carriers of CF. Babies with a positive test result will need a sweat test at about 6 weeks of age to determine whether the baby has CF or is only a healthy carrier. A healthy carrier is not affected with CF and their body functions normally.
- Galactosaemia — An extremely rare disorder only affecting 1 in 40,000 babies. The disorder is caused by the accumulation of galactose (a type of sugar in milk) in the blood. Prompt treatment with special galactose-free milk will prevent serious illness. Without treatment, a baby may become very sick and die.
- Other rare disorders of metabolism — The blood tested in the heel prick test can be tested for a range of other very rare metabolic disorders such as such as amino acid, organic acid and fatty acid oxidation defects. Collectively these disorders occur in 1 of every 4,000 babies and so are rare. These conditions are often treatable with specialised care and diets.
Getting the results
All of the disorders listed in this article are rare, and in most babies tested the results are normal. Parents are only contacted if there are concerns with the test results.
A few babies will need to have a second blood test. This is usually because the first test did not give a clear result. Most babies’ second tests will give normal results and your doctor will be informed.
If any of the tests return a positive result and your baby is thought to have one of these conditions, you will be told as soon as possible. Your baby may need further tests to confirm the results and you may be given an appointment with a specialist so that appropriate treatment can begin.
Storage of newborn screening samples
The National Pathology Accreditation Advisory Council requires newborn screening samples to be stored. After the dried blood spot has been tested, it will be stored in a secure locked area until the child is 18 years of age. In some states you can request the card is returned to you after 2 years.
The stored sample is retained to allow for quality control, and may be used for ethics committee approved research after identifying information has been removed.
The sample may also be used for further testing at the request of the parent or guardian, to provide new medical information for the benefit of the family. After a fixed period (dependent on the state/territory), samples are destroyed.