This document summarizes antepartum fetal assessment techniques. It describes the aims of fetal monitoring as ensuring fetal growth and well-being. Various clinical evaluation methods are outlined, including fetal movements, breathing, biophysical profile, amniotic fluid volume, and Doppler velocimetry. Specific tests like non-stress tests and contraction stress tests are also defined. The document provides details on interpreting test results and guidelines for testing frequency from organizations like ACOG. The overall purpose is to screen for high-risk factors affecting the fetus and guide management to improve perinatal outcomes.

1. Antepartum Fetal Assessment
Presentor: Dr.Tanya Das
Moderator:Dr.Dipty Shrestha

2. contents
 Introduction
 Clinical Evaluation
 Fetal movements
 Fetal Breathing
 Contraction Stress Testing
 Non Stress Test
 Acoustic stimulation Test
 Biophysical Profile
 Amniotic Fluid Volume
 Doppler Velocimetry

3. Introduction
 Aims of antenatal Fetal Monitoring
1. To ensure satisfactory growth and well being of fetus
throughout pregnancy
2. To screen out the high risk factors that affect the growth
of the fetus
 Rationality of Antenatal Fetal Tests:
1. Tests must provide information superior to that of
clinical evaluation
2. Should be helpful in management to improve perinatal
outcome
3. Benefits of tests must outweigh the potential risks and
the costs

4. Significance of Fetal Testing
 Between 1970-1985, 15 year duration, fetal surveillance
increased from less than 1 percent in 1970 to 15 percent in
1980
 Women undergoing NST had a nonsignificant decreased
risk for stillbirth compared with those not tested– 3.6
versus 9.2 percent respectively
 A study conducted in 2003 concludedin their study of 36
preterm infants, that by the time fetal compromise is
diagnosed, fetal damage has already occurred
 Testing for biophysical profile decreased the rate of
cerebral palsy to 1.3 percent as compared to 4.7 percent in
untested women.

5. Antepartum Surveillance
 First Trimester
1. Clinical evaluation
2. Ultrasound evaluation
3. Chorionic Villus Sampling
4. Genetic screening using fetal cell free DNA
 Second Trimester
1. Amniocentesis
2. Fetal Echocardiography
3. Fetal Blood Sampling

6.  Third Trimester
1. Clinical Evaluation
2. Fetal biophysical Profile
3. Ultrasound Evaluation
4. Non Stress test
5. Contraction Stress Test
6. Vibroacoustic Stimulation Test
7. Fetal Doppler Ultrasound

7. Clinical evaluation of fetal well being
 First Visit
• Size of uterus determined: helps in estimating the correct
duration of gestation
 Subsequent visits
1. Maternal weight gain
2. Blood pressure
3. Size of uterus and fundal height

8. Antepartum Fetal Surveillance
 Objectives( ACOG)
1. Prevention of fetal death
2. Avoidance of unncessary interventions

9. Fetal Movements
 Passive unstimulated fetal activity commences
at 7 weeks
 Becomes organised between 20-30 weeks of
gestation
 Fetal movements maturation- until 36 weeks,
behavioural states established

10.  4 fetal behavioural states:
1. State 1F: quiescent state- quite sleep
2. State 2F: Frequent Gross body movements, continuous
eye movements, wider oscillation of FHR
3. State 3F: continous eye movements in absence of body
movements and no FHR acceleration
4. State 4F: Vigorous body movements, eye movements,
FHR accelerations; corresponds to awake state
 Mean length of quiet or inactive state-23 minutes

12.  Clinical Application
1. Cardiff ‘count 10’ formula- report if
: <10 movements occur in 12 hours on 2 successive days
:no movement perceived even after 12 hours in a single day
2. Daily Fetal Movement Count
Three counts each of 1 hour duration (morning, noon,
evening); if <10 in 12 hours(or less than 3 in each hour)

13. Fetal Breathing
 Chest wall movements are discontinuous in fetus :
paradoxical chest wall movements
 >1 episode lasting >30 seconds
 2 types of chest wall movements:
1. Sighs or gasps(1-4/minute)
2. Irregular bursts of breathing (240 cycles/minute)

16. Biophysical Profile

18. Modified Biophysical Profile
 First line screening tests
 Combined non stress test with Amniotic fluid volume
 Less time to perform
 Less expertise
 Excellent fetal surveillance tool
 False negative rate of 0.8 per 1000 and false positive rate
of 1.5percent

19. Amniotic Fluid Volume
 Decreased uteroplacental perfusion may lead to
diminished fetal renal blood flow– decreased urine
production– oligohydramnios
 ACOG(2012a)- amnitoic fluid index <5cm or a
maximum deepest vertical pocket <2cm are
acceptable criteria for diagnosis of oligohydramnios

20. Contraction Stress Test
 Measure fetal response to transient reduction in fetal
oxygen delivery during uterine contraction
 Test of uteroplacental insufficiency
 Intravenous Oxytocin used to induce contractions and
FHR response is recorded
 Nipple stimulation can be used alternatively to induce
contractions

22. Non Stress Test
 Test of fetal condition
 FHR accelerations in response to fetal movement is
recorded
 National Institute of child health and human development
fetal monitoring workshop-
• > 32 weeks- accelerations of 15 beats per minute for >15
seconds above baseline
• <32 weeks- accelerations of 10 beats per minute for > 10
seconds above baseline

23.  Normal NST (ACOG and AAP 2012)
‘ 2 or more accelerations that peak at 15 beats per minute
or more above baseline each lasting for 15 seconds or
more in a 20 minute reading’
( >40 minute Tracing required to conclude insufficient fetal
activity accounting to fetal sleep pattern)
90% or higher false positive rate

25.  Abnormal Non Stress Tests
• NST non-reactive for 90 minutes: 93% associated with
perinatal pathology
• Baseline oscillation <5 beats per minute
• Absent accelerations
• Late deccelerations with uterine contractions
• Variable Deccelerations, if non-repetetive and brief—less
than 30 seconds—do not indcate fetal compromise
• Repetetive variable deccelerations: at least 3 in 20 minutes
or lasting more than 1 minute– suspect compromise

29.  Interval Between Testing
ACOG(2012a): twice weekly for women with post
term pregnancy, multifetal gestation, type 1 diabetes
mellitus, fetal growth restriction, gestational
hypertension

30. Acoustic Stimulation Tests
 Loud external sounds have been used– provoke heart rate
accelerations
 Commercially available stimulator – stimulus of 1 to 2
seconds , can be repeated upto 3 times for up to 3 seconds
 Positive response is defined as the rapid appearance of
qualifying acceleration following stimulation

31. Doppler Velocimetry
 3 fetal vascular circuits– umbilical artery, middle cerebral
artery, and ductus venosus are assessed
 Aid in decision to interfere in growth restricted fetus

32.  Umbilical Artery Velocimetry
• Systolic-diastolic ratio(S/D) ratio is considered abnormal
if it is above 95th centile for gestational age or if diastolic
flow is decreased or reversed
• Absent or reversed diastolic flow– signifies increased
impedance to umbilical artery blood flow
• Results from poorly vascularized placental villi- seen in
fetal growth restriction
• Seen in IUGR, PIH, GDM, Post term pregnancy, Anti-
phospholipid antibody syndrome

34.  Middle cerebral Artery
• Hypoxic fetus attempts brain sparing by reducing
cerebrovascular impedance and thus increasing
blood flow
• Incresed diastolic velocity, decreased S/D ratio
• Seen in Rh Isoimmunisation, Fetal Anemia, D
alloimmunisation and IUGR

36.  Ductus Venosus
• Most recent
• Best predictor of perinatal Outcome
• Information about forward cardiac function
• Negative or reversed flow in ductus venosus is a late
finding in fetal acidemia

38.  Antenatal Testing Recommendations
• Majority of high risk pregnancies, recommended
testing begin by 32 to 34 weeks
• Pregnancies with severe complications might require
testing as early as 26-28 weeks
• Frequency of testing: 7 days

39.  Thank you