Newborn Screening Tests



Newborn Screening Tests

Having a newborn baby is both the biggest joy and potentially the most anxiety provoking event in our lives!  After waiting 9 months, the moment comes and your little bundle of love emerges, cries, feeds and we rejoice.  They seem healthy!   But wait – could there be something actually wrong that we don’t even see?   This is absolutely not the way I want you to feel…but could potentially be true.   So each and every baby goes through a series of “just in case” newborn tests to rule out the rare case of something wrong.

Let’s go through each of these tests so we can understand better what we are looking for. 

(The tests will be the same for all Brooklyn newborns, and for all babies born in New York State.    There are some tests that vary state to state).

Newborn hearing test

Each and every baby will get a newborn audiology test, just to make sure they don’t have a congenital problem with their ears and the nerves that help with hearing.  The test doesn’t hurt the baby at all and just takes a few seconds actually.  There are times where the actual test “doesn’t pick up the results” properly and so you may leave the hospital with a note saying you should “follow up” and do another hearing test.  A pass means just that – your baby should hear normally and this is great news.  They still may have problems in the future with acquired hearing difficulties, such as fluid in the ears after a cold or a perforated ear drum after a severe ear infection, but a normal passing test rules out the congenital problems with hearing. 

A fail, or inability to get a pass should not invoke too much concern, as the vast majority of these results are “false positives” and on the recheck the baby hears perfectly.  The testing itself – both the machine and the actual test are not perfect.  In fact, for many years we didn’t conduct this testing because we didn’t feel it was accurate enough.  So if you baby doesn’t pass initially we will conduct a follow up audio with a pediatric audiology specialist (the newborns won’t raise their hand with each beep, so they will indeed need a special newborn audio test with the audiologist) in the next few weeks and only if there is a true problem will we meet the ENT specialist to make a plan. 

Critical Congenital Cardiac Disease

What!?  That sounds horrible!  Well it can be, so let’s rule it out with a simple quick test.   By checking two quick oxygen measures with a painless monitor on the finger and toe (no blood tests needed) we can rule out most of the serious congenital cyanotic heart issues.  Your baby may still have a heart murmur at some point in their life, but this will help to rule out the most serious ones that can make a newborn baby very sick and cut off oxygen to their body.  Most often the doctors in the hospital will merely say “all is good!”, or “your baby passed all of their tests”, and this is fabulous news!  If there is indeed an issue or problem, this could be serious, and it won’t be a follow up in a few weeks – it would be an immediate pediatric cardiology consult, an echo/sono test of the heart and immediate treatment – but luckily this is extremely rare.   

The Newborn Screen blood test (aka PKU test)

Every single newborn baby will get a newborn screen blood test (from the heel) and with just a few drops of blood we will be checking for over 40 different types of diseases.  Most of these conditions are quite rare, but all of them are very important to catch early.  Furthermore, a baby could appear perfectly healthy at birth, but then get sick from some of these conditions, so it really is crucial to check the newborn screen tests.  The tests are most accurate AFTER 24 hours of life, so for those born at home or in a birthing center, we can draw the tests here on your first visit.

The state lab is running the tests for all babies, and they will report back to the hospital or midwife as well as the parent and pediatrician any abnormal results.   It usually takes a full two weeks to get back all the tests.   They check for sickle cell, thyroid disease, cystic fibrosis, PKU, immune deficiencies and a host of other thankfully rare enzyme and amino acid deficiencies.   Getting back a fully normal result is a big sigh of relief!   But if you do get back a letter or call from the state lab or your pediatrician regarding a slightly abnormal test, I wouldn’t worry just yet.  Many of these tests are meant to NOT MISS a disease, but in catching all those babies who may have the true disease, there are some false positives.  So your pediatrician will decide with you whether we repeat the entire newborn screen (but that can take another 10-14 days to get back results) or do we send of specifically the actual blood test for that particular disease or enzyme. 

Other things that happen to newborns at birth:

Every baby gets some eye ointment to prevent certain types of conjunctivitis.   I think the ointment is safe and doesn’t have any side effects.  Every baby gets a vitamin K shot for the rare case of true vitamin K deficiency as that condition could be deadly.  This is not a vaccine, and the pain is there, but it is a safe medicine to administer. 

Hospitals do usually recommend a Hepatitis B vaccine for the baby.  If you know for sure that Mom doesn’t have Hep b disease – she is normal/negative and immune – then you really don’t need the birth dose of the Hep b, and we will give that along with the other vaccines as part of our normal vaccine schedule.  So you can safely defer that vaccine if you are sure you don’t have the disease to pass to the newborn during delivery.  

Weight loss and Jaundice

Every baby will lose some weight, and every baby will have some level of jaundice, but if there is too much weight loss (more than 10% of birth weight) or if the jaundice level is rising too quickly or getting towards 20 or above, they may recommend special lights to bring the level down.  You’ll never forget the birth weight of the baby, but make sure they give you an accurate discharge weight, so we can compare the weight on our first visit – on day 3, 4 or 5 of life.  And make sure they give you the actual bilirubin or jaundice level, and even the time it was drawn!  A level of 10 at 36 hours of life is pretty normal, but a level of 12 at 20 hours old could be too high too soon!   In most cases the jaundice level peaks at day 3-4 and then comes down on its own, but we will check for jaundice and many other things at our first comprehensive newborn exam.  We save newborn slots every day, so just call for an appointment! 

Hopefully every single test the hospital conducts is normal!  But just call me with any questions, even from the hospital, and I’ll help to review all the data and make a plan with you that best serves your newborn!


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