We provide an overview of the screening tests performed for all infants prior to nursery discharge: the newborn metabolic screen, newborn hearing screen, and critical congenital heart defect screen. We are joined by Abby Patterson, MD, Assistant Professor of Neonatal-Perinatal Medicine at the University of Texas Southwestern Medical Center.
Dr. Neeta Goli:
Welcome to Newborn News, a podcast where we discuss educational topics from medical professionals who care for newborns. I'm your host, Dr. Neeta Goli, a pediatrician in the UT Southwestern Newborn Nursery. Welcome back. In this episode, we'll learn about screening tests performed in the newborn nursery. We are once again joined by Dr. Abby Patterson, who you may remember from previous episodes. Thanks for joining us again today.
Dr. Abby Patterson:
It's great to be back.
Dr. Neeta Goli:
So as a reminder, from our Newborn Nursery Basics episode, all newborns undergo three screening tests before they go home. So that's the newborn screen, the hearing screen, and the critical congenital heart defect screen, or the CCHD screen. In this episode we'll talk about each of these in more detail. So let's talk about the newborn screen first. What is this?
Dr. Abby Patterson:
Yeah, so the newborn screen is a blood test where we collect blood from the heel of the baby usually after 24 hours of life, and the blood is collected on filter paper. In Texas, there's five circles on the piece of paper. So if I'm asking a family, if baby had it done, I ask, "Did the baby have his blood on five circles?" And that blood after it's dried is sent to a state laboratory who punches out the little pieces of paper and is able to use that dried blood to test for many different disorders.
Dr. Neeta Goli:
Okay. And what kind of disorders do they test for?
Dr. Abby Patterson:
Yeah, so the newborn screen varies a little bit in what they test for state by state, so check your own state's guidelines. But in general, it tests for diseases that if caught early have treatment that could change the outcome of the baby. So that's diseases where early treatment, even before symptoms, it helps the baby do better long-term. And it's also a dynamic list. So it changes all the time. For example, Texas just added X-linked adrenoleukodystrophy in August of 2019. So if you're listening to this a couple of years from now, check the list, it might be different than when we're recording.
Dr. Neeta Goli:
And how common is it for the newborn screen to pick up an abnormality?
Dr. Abby Patterson:
Yeah, so it actually in the US picks up about 4,000 babies a year, so about 11 babies a day that have a disorder that's identified by newborn screening.
Dr. Neeta Goli:
Okay. So the screen has to be done after baby turns 24 hours of life. Why is that?
Dr. Abby Patterson:
Yeah, the importance for that is that some of the disorders we test for, there needs to be some metabolic buildup to be able to adequately screen for the disorder. So if you perform too early, those metabolites haven't built up and you'll get a false negative.
Dr. Neeta Goli:
Okay. So now we know the newborn screen. We can move on to the hearing screen. Can you tell us a little bit more about that?
Dr. Abby Patterson:
Yeah. So the hearing screen is given to all babies before they leave the nursery. It can identify congenital deafness early, and that allows early intervention as with anything in pediatrics. The earlier we intervene to improve development, the better. It's also important to know that for most babies, we look for reasons for the deafness and about 15 to 20% of congenital deafness can be attributed to CMV. So at our center, we will automatically screen for CMV if a baby does not pass their hearing screen in the nursery.
Dr. Neeta Goli:
Okay. And then I know there are two different kinds of hearing tests that can be performed. Can you talk about which one we do in our nursery?
Dr. Abby Patterson:
Yeah. The two different kinds are the auditory brainstem response and the otoacoustic emissions. We do the auditory brainstem response or ABR at Parkland.
Dr. Neeta Goli:
So what kinds of things should a family expect in terms of how long should the test take? Is it going to be done in the room or will baby need to go to the nursery for that to be done?
Dr. Abby Patterson:
Yeah. So the newborn hearing screen can be done any time after birth. We don't have to wait any length of time, is the first thing that we tell parents. Typically at Parkland, we'll do at least the first attempt in the room with moms so baby and mom don't have to be separated. Typically the test is pretty fast, I would say 15 minutes or less though that can vary based on the compliance level of the child. My daughter was a very feisty baby so her first test probably took about 20 to 30 minutes and she didn't pass because she wouldn't stop moving to participate in the test. So it's also important to tell parents that sometimes the baby does not pass on their first try. Sometimes it's like my daughter, where they're not cooperating. Also, the baby sometimes can have some fluid still in their ear especially if the test is done pretty soon after birth.
Dr. Abby Patterson:
So in those cases, we'll repeat the screen again the next day, usually about 24 hours later. If the baby still doesn't pass on the second try, then the baby will get tested again at two weeks as an outpatient. I like to reassure families in that situation, that of the babies that do not pass their hearing screen in the newborn nursery, the majority of them will pass at two weeks. Usually it's either a state-related problem or they still have fluid in their ears that's preventing them from adequately responding to the test rather than a true hearing problem.
Dr. Neeta Goli:
And what do you mean by state-related?
Dr. Abby Patterson:
Yes. State-related usually means they're either very fussy or they're moving around a lot, and then the test isn't as accurate.
Dr. Neeta Goli:
Feisty babies. Yes. So finally the CCHD screen, can you tell us what CCHD means?
Dr. Abby Patterson:
So, that's really distinguishing the difference between congenital heart defects and critical congenital heart defects. So really congenital heart defects are any lesion within the heart. So for example, a VSD is the most common congenital heart defect. However, that's not a critical congenital heart defect. When we talk about critical congenital heart defects, we often are talking about those diseases that are going to either cause the baby to be in distress early, or those diseases that are going to mean the baby needs intervention fairly soon after birth. So when we think about those, we think about things like hypoplastic left heart syndrome, pulmonary atresia, truncus arteriosus, transposition, tricuspid atresia, TAPVR, those big, bad, and scary diseases that scare us when we hear a murmur.
Dr. Neeta Goli:
So how common is it to find one of those?
Dr. Abby Patterson:
So critical congenital heart defects, there's about 7,200 babies a year. So that's about 20 babies per day in the United States.
Dr. Neeta Goli:
Okay. So how is the test done? How are we looking for these?
Dr. Abby Patterson:
Yeah. So the test is actually more simple than you think it is. Again, this is a screening test, not a diagnostic test. So we'll get pre- and post-ductal oxygen saturation measurements. So for pre-ductal, we'll measure their oxygen saturation in their right hand and for post-ductal, we use either one of their feet. And then to analyze the test, we look to see that both oxygen levels are greater than 95% and that there's no more than a 3% difference between the two locations.
Dr. Neeta Goli:
So what happens if that's not the case?
Dr. Abby Patterson:
Yeah. So if the first test is abnormal, the nurse will repeat the test again in an hour. And then if the baby's still doesn't pass, the nurse will call the provider assigned to the baby, they'll come and assess the baby, and if their assessment is normal, then they'll repeat the test again in another hour. If the baby doesn't pass for a third time, they'll be transferred to the NICU for a more thorough evaluation for critical congenital heart disease.
Dr. Neeta Goli:
So say you're the provider that's assigned to the baby and you're called by the nurse who tells you that the baby didn't pass the CCHD screen twice. When you go to assess the baby, what kind of things are you looking for?
Dr. Abby Patterson:
Yeah. So in that case, you're really looking for signs of heart disease or heart failure. So going from head to toe, I always think first about color. So you want to make sure you look at the baby's color. Does the baby look pink or does he look dusky? Next, you want to assess the sounds of their heart. So you'll listen to them and hear, do they have a murmur? If so, what are the characteristics? Where is the location? Does it radiate? All of those typical things you would think about when you're analyzing a murmur. You also want to make sure you check the baby's pulses, both brachial and femoral. You want to make sure you're feeling both sides at the same time to assess for any discrepancies. And then also to make sure that the brachial and femoral pulses feel equally strong.
Dr. Abby Patterson:
You'll also feel on the belly to make sure there's no hepatosplenomegaly that could be a sign of heart failure. Also, as you're looking for the baby, you want to make sure that they look like they're well. Has the baby feeding well? Are they in respiratory distress? Those signs could make you lean towards an evaluation sooner if the baby's showing symptoms of heart disease.
Dr. Neeta Goli:
Okay. So thanks so much. This has been really educational and thanks again for taking the time to share all this information with us. You've shared your tips for success and your favorite part of your work day in previous episodes. So today we can talk about, what is the most important thing for a resident to do when they're on call?
Dr. Abby Patterson:
Yes. So this ties in really well with what I just talked about: when in doubt, go examine the baby. Because they'll learn a lot when you just look at them with your own eyes.
Dr. Neeta Goli:
Okay. Thanks so much.
Dr. Abby Patterson:
Thanks for having me.
Dr. Neeta Goli:
Thanks for listening to Newborn News. We hope you join us next time. If you like what you hear, make sure to subscribe and leave us a review. If you have questions, comments, feedback, or suggestions for future episodes, please email me at NewbornNews@utsouthwestern.edu. As a reminder, this content is educational and is not meant to be used as medical advice. Views or opinions expressed in this podcast are those of myself and my guests and do not necessarily reflect the views of the university.