Everyone welcome back to parently Dr. Boyd here. Today we're talking about the non stress test or the nst or the fetal non stress test. What is this test? When is it performed? Why is it performed and who is it performed on? The non stress test is an evaluation of the fetal heart rate.

It is performed, usually in the doctor's office or at the hospital by strapping two devices on your abdominal wall. One man monitors the fetal heart rate, the other monitors uterine contractions. With this information, we can make assessments of fetal well being. Now, the non stress test looks at several variables. The first thing it looks at is the fetal heart rate baseline. The baseline means it's an average of what the heart rate is doing up and down and gives you a baseline average.

This average should be between 120 and 160. If the baseline falls below 120, it's called Braddock. cardia. If it's above 160, it's called tachycardia. So we want this baseline to be in that range of 120 to 160. The second assessment we look at is the very variability.

The variability is the evaluation of a neurological process that occurs in the baby, where we determine a sawtooth looking pattern on the fetal non stressed us. And what does that mean? Instead of a straight line variability, we want to see a sawtooth pattern on the field, heart rate variability, and we'll provide that information as an aside so you can see what that looks like. There is Good variability or excellent variability. And then there's poor variability. Good variability means we have a defined up and down sawtooth pattern that is in a defined period of time.

Poor variability is a decreased sawtooth pattern. And again, we'll provide information to the side here for you to see. The third variable is my baby's heart rate accelerations. So when the baby moves, the heart rate should go up. And we should see two accelerations of the baby's heartbeat in a 20 minute period of time. And that heart rate acceleration should be at least 15 beats above baseline.

So an example if my baby's baseline is 150, I should see a minimum heart rate acceleration with fatal movement of 165. And then we should see two of these in a 20 minute period of time. In that scenario, we assess whether the baby is reacting IV or nonreactive, non stress test, and then we can categorize that based on a category of one, two, and three that we're going to discuss here in a minute. The fourth variable is uterine contractions, and how does that relate to my baby's heartbeat rate and acceleration or deceleration. When you have a uterine contraction, almost all baby's heart rate goes down a little bit. If the heart rate goes down with the contraction, that's not a concern.

That simply means that the baby's head has been compressed, and oftentimes in labor, we will see that However, if the baby's heart rate goes down after the uterine contraction, that's called a late deceleration, and we would want further evaluation being performed. That will be done in if it's in the office using a either continued monitoring or a biophysical profile that will address your on the later video. After we've done a complete non stress test, which is a period of time of 20 minutes to an hour, we will assign a reactive status to your baby or nonreactive status to your baby. Or we will categorize the category one means healthy category two, which means we need further monitoring or a category three, which means imminent delivery. Now, when are these non stress tests performed, we're going to categorize this as a low risk patient or a high risk patient.

Almost all patients fall into the low risk category. And so they would have a non stress test if they call the office and said my baby's activities diminished. In other words, I'm not feeling the baby like I should. Oftentimes we will assess the baby with a non stress test to reassure the patient that there is adequate and normal fetal well being. Now, there's also the low risk mom that goes over her due date in that scenario Typically we do non stress test twice a week, Pastor due date, up until the point where she gets delivered or induced. There's also the high risk mom.

So the mom that has hypertension, a mom that has preeclampsia, the mom that has cardiac disease or kidney disease, or the mom that has diabetes, type one or type two, many of those patients, if not all of them, will be assessed by non stress testing sooner than her third trimester. Now, what do I mean by that we can start non stress testing as soon as 28 weeks that's the soonest that non stress testing can be done and used as a tool to assess the well being prior to 28 weeks. Non stress testing is not used as a tool to assess a well being after 28 weeks. If you're in a high risk category. your healthcare provider may do non stress testing as often as every day every week, every two weeks every month, that's based on your high risk category. Now, non stress testing is a tool that's very supported by the literature to assess fetal well being.

However, it's not the best tool, the best tool is a biophysical profile. And we will address that in a separate video. I hope this was helpful. This is very important information that you as a patient can use to prepare you for what your healthcare provider may recommend. Today we're doing a non stress test on a woman that is 27 weeks pregnant. The registered nurse is putting her monitor on the first monitors evaluation of the fetal heart rate.

As I've stressed in prior videos, the normal heart rate on the baby that's in utero should be between 120 and 160 beats per minute. So you can hear the baby's heart beating, and it's in that range. The second monitor that's being put on is monitoring of the uterus for uterine contractions. You can see typically, the lower monitor is for heart rate the upper monitor just for uterine contractions. We will monitor in a normal non stress test a minimum of 20 minutes. And this will give us an evaluation of fetal well being.

So the patient sometimes is asked to drink some fluids. Sometimes they get IV fluids, sometimes they have to drink something sweet like some apple juice. This will all improve the chances that the baby will be normal and it's in its heart rate evaluation. After we monitor for a minimum of 20 minutes, we score this as a category one, two or three. So this is how A non stress test is performed. Thanks, y'all.