Antenatal Testing

00:01 Now, we will discuss Antenatal Testing.

00:06 So the purpose of antenatal testing is to ensure fetal well-being.

00:10 And when we say, reassure us or ensure fetal well-being, we mean that there are no signs of fetal asphyxia.

00:18 So let's first talk about the non-stress test.

00:22 So the non-stress test is performed by doing the external fetal monitoring to look at the fetal heart rate.

00:29 We then determine if the fetal heart rate is reactive, which means fetal well-being is reassured, or is it non-reactive, meaning there's additional testing needed to be done to assure fetal well-being.

00:42 Reactive. And this is very important means that there is two accelerations of greater than 15 beats per minute, lasting at least 15 seconds over a 20 minute time period.

00:53 So again, you're looking at a 20 minute time period on the external fetal monitor, and you're looking to find two accelerations of greater than 15 beats per minute, each lasting for at least 15 seconds.

01:06 So the next type of antenal testing is the biophysical profile.

01:11 Now with the biophysical profile, you're looking at five different categories expecting to see certain things in this category.

01:19 Patients are given a two if the fetus performs the maneuvers that we're looking for, and a zero if they do not perform the maneuvers.

01:28 Again, you have 30 minutes to observe it.

01:30 So we're looking at fetal movement.

01:33 We're looking at fetal tone, fetal breathing, the amniotic fluid, and again, the non-stress test.

01:40 So with the fetal movement, we're looking to see three gross movements within that 30 minute time period.

01:47 Fetal tone is looking for fine movements, like the hands moving the fingers opening and closing the palm.

01:53 Fetal breathing, we're looking for sustained breathing for 30 seconds over that 30 minute time period.

01:59 Amniotic fluid volume, really, we're just looking at the maximum vertical pocket and we want that to be at least two centimeters.

02:06 And then we've already discussed the non-stress test.

02:10 So if we have a score of eight, that is reassuring.

02:12 That means that that fetus is doing well and there's no signs of fetal asphyxia.

02:17 If there's a score of six, this is considered equivocal.

02:21 So it doesn't mean that we are reassured but it also doesn't mean that the baby is concerning for asphyxia.

02:27 However, if the patient is term, meaning 37-weeks, that means we need to deliver that fetus.

02:34 At a score of four, it is a little bit concerned this for asphyxia and we do need to deliver at that point.

02:41 So the biophysical profile can be used when the non-stress test is not reactive as a confirmation that the baby is doing okay.

02:51 So the next antenatal testing that we use is a contraction stress test.

02:56 So with the contraction stress test, we induce contractions, and that can either be through nipple stimulation, or it can be induced by given pitocin.

03:05 And we're looking to see that a patient has contractions over a 10-minute timeframe.

03:11 Now, this test, we do not want to be positive.

03:14 So it's a little different than the non-stress test.

03:17 If the test is positive, that means that more than 50% of the contractions are associated with a late deceleration.

03:25 The test is equivocal when there's intimate late decelerations but less than 50%.

03:31 And the test is negative when there's less than 50% of the contractions associated with late decelerations.

03:37 Again, for the contraction stress test, we want a negative result to reassure us that the fetus can tolerate labor.

03:45 Pay attention to this slide because this is high yield.

03:50 And then the final test is the Umbilical artery doppler.

03:53 Now this is a test is performed by doing an ultrasound looking at the doppler of the umbilical artery.

04:00 And we do this when we are suspected in fetal growth restriction.

04:04 Now our results can show a normal S/D Systolic/diastolic ratio or it can show absent or even worse it can show reversal flow.

04:14 If it is, if there were flow is absent or reversal then that indicates that there is an increased resistance in the placenta.

04:23 So let's look at a question.

04:25 A 27-year-old gravida 1 para 0 female at 28 weeks and 3 days of gestation with a history of chronic hypertension presents for an antenatal visit.

04:35 She has had no issues this pregnancy.

04:38 All antenatal testing has been within normal limits.

04:41 She takes labetalol for her chronic hypertension.

04:44 On physical exam, her blood pressure is 140/95.

04:47 The fetal heart rate is 150 beats per minute, And the fundal height for the mom is 23 centimeters.

04:56 Now when we think about that, 23 centimeters at 28 weeks gestation that sounds a little small to me.

05:04 So the next best step in her management is...

05:07 A. A fetal ultrasound.

05:09 B. Fetal doppler of the umbilical artery.

05:11 C. Contractions stress test.

05:13 or D. Biophysical profile.

05:17 So in this case, we first want to do a fetal ultrasound.

05:20 Now, there's lots of reasons why the fundal height may be small.

05:23 It could be because there's decreased amniotic fluid.

05:26 It could be because the baby is small, or it could be our measurements are not that great.

05:30 So we want to confirm that the measurement is small first by fetal ultrasound.

05:34 If the fetus is indeed small, then the fetus will warrant a fetal Doppler of the umbilical artery.

05:40 But the next best step in her management is to perform the fetal ultrasound.