This document discusses various antepartum fetal assessment tests including fetal movement counting, nonstress tests (NST), biophysical profiles (BPP), contraction stress tests (CST), and Doppler flow studies. The NST evaluates fetal heart rate patterns in response to movement or stimulation to assess well-being. The BPP comprehensively evaluates fetal tone, movement, breathing and amniotic fluid volume. The CST assesses fetal heart rate patterns during induced contractions to identify signs of distress. Doppler flow studies evaluate umbilical artery blood flow waveforms to identify signs of placental insufficiency. Together these tests aim to monitor fetal well-being during pregnancy and identify those in need of delivery.

1. ANTEPARTUM
TESTING

2. Antepartum Fetal Assessment
 Fetal movement counting
 Antepartum fetal heart rate testing
 Biophysical profile
 Doppler velocimetry

3. Which test to use?
 Nonstress test
 Biophysical profile, modified biophysical profile
 Contraction stress test
 Low incidence of unexpected fetal death
 Increase in time, cost and inconvenience
 Doppler velocimetry

4. Fetal Movement - Advantages
 Is a daily assessment
 Easy and Non-invasive
 Requires no special equipment
 Mom becomes more in tune with fetus and more
likely to recognize changes in behavior

5. Fetal Movement Counting

6. Purpose of NST
 Determine if:
 Inadequate delivery of oxygen and/or nutrition in
fetal tissue
 Inadequate placenta exchange due to decreased
blood flow, decreased surface area or increased
membrane thickness.
 Inadequate maternal nutrients or oxygen to the
placenta

7. Nonstress Test (NST)
 FHR accelerations reflect CNS alertness and activity
(fetal well being)
 Absence of FHR accelerations may reflect CNS
depression caused by hypoxia, drugs, fetal sleep, or
congenital anomalies.
 The endpoint of the NST is the presence or
absence of FHR accelerations within a specified
period of time

8. Performing the NST
 Position patient in semi-fowler or left lateral tilt (to
minimize supine hypotension)
 Apply external monitors for contraction and FHR
measurement
 Mark tracing when fetal movement is felt or heard
 Fetal sound stimulation may be used to elicit a response.

9. Nonstress Test (NST)
 Accelerations of the FHR occur with fetal
movement, uterine contractions, or in response to
external stimuli.

10. Nonstress Test (NST)
 Target criteria is 2 accelerations of at least 15 beats
per minute (BPM) for 15 seconds in a 20-minute
period
 A healthy fetus < 32 weeks’ gestation may use at
least 2 accelerations of 10 beats per minute (BPM)
for 10 seconds in a 20-minute period
 The more remote from term, the more likely that
nonreactivity will be due to fetal prematurity.

11. Interpreting the NST
 Reactive: Presence of at least 2 accelerations in a 20
minute period
 Non reactive: FHR does not accelerate to meet
criteria or the fetus does not move
 May extend the testing period to 40 minutes or perform a
back-up test.
 Reactive or Nonreactive with decelerations:
individualize management

12. Biophysical Profile (BPP)
 Biophysical activities that can be recorded
with real time ultrasound:
 Fetal movement (FM)
 Fetal tone (FT)
 Fetal breathing movements (FB)
 Amniotic fluid volume (AFV, also known as AFI)

13. Biophysical Profile (BPP)
 Assessment of umbilical blood flow provides
information on blood perfusion of the
fetoplacental unit.
 Activities that become active first in fetal
development (FT, FM) are the last to disappear
when asphyxia arrests all activities.
 Activities that become active later in gestation
(NST, FBM) will be abolished 1st
in cases of
hypoxia and acidosis.

14. Biophysical Profile (BPP) - Scoring
 Each assessment
 When normal: 2
 When abnormal: 0
 Highest Score: 10, Lowest Score: 0
 Accuracy improved by increasing the number of
variables assessed.
 Overall false negative rate: 0.6/1000

15. Biophysical Profile (BPP) - Scoring
 NST: reactive – as described earlier.
 FBM: present - at least 1 episode of at least 30
seconds duration (within a 30 minute period).
 FM: present - at least 3 discrete episodes.
 FT: normal - at least 1 episode of extension of
extremities or spine with return to flexion.
 AFV: normal – largest pocket of fluid greater
than 1 cm in vertical diameter.

16. Purpose of Contraction Stress Test
 A hypoxic fetus will manifest late decelerations
when uterine blood flow is compromised
 Late decelerations correlate with stillbirth, IUGR,
and low Apgar scores.

17. Contraindications to CST
 PROM
 Previous classical cesarean delivery
 Placenta previa
 Incompetent cervix
 History of premature labor in this pregnancy
 Multiple gestation

18. Performing the CST
 Uterine contractions in excess of 30 mm Hg
create an intrauterine pressure that temporarily
stops uterine blood flow.
 A well oxygenated fetus has reserve to tolerate
contractions
 Contractions for CST can be achieved through:
 Oxytocin challenge test (OCT)
 Breast (nipple) stimulation

19. Interpretation of the CST
 Negative: no late decelerations and adequate FHR
recording
 Positive: Late decelerations present with the
majority of contractions (without excessive
uterine activity)
 Equivocal test results: Suspicious,
hyperstimulation, unsatisfactory.

20. Doppler Flow Studies
 In Normal conditions the placenta offers little
resistance to fetal and maternal blood flow, even
during diastole (i.e., between heart beats)
 Useful in evaluation and management of pregnancies
complicated by conditions such as
 Suspected fetal growth restriction
 Red blood cell isoimmunization
 Pre-eclampsia

21. Doppler Flow Studies
 The most commonly assessed Doppler flow
study of the fetus is the umbilical artery
Systolic flow
Diastolic flow
Normal blood flow

22. Doppler Flow Studies
 Waveform may show decreased/absent diastolic
blood flow in the umbilical vessels of a fetus
 Decreased/absent blood flow indicates that the
fetus may not be receiving enough blood,
nutrients, and oxygen from the placenta
Systolic flow No end
Diastolic flow

23. QUESTIONS?