Introduction:

The goal of antepartum fetal assessment
1. Identify fetuses at risk of intrauterine death or
other complications of intrauterine asphyxia
2.Intervene to prevent these adverse outcomes.

The main techniques for fetal assessment.
1.Nonstress test
2.Biophysical profile
3.Modified biophysical profile
4.Contraction stress test
5.Fetal movement count
PHYSIOLOGICAL BASIS FOR FETAL TESTING
1.Antepartum testing is based on the fetus
responds to hypoxemia with a detectable
sequence of biophysical changes,
beginning with signs of physiological
adaptation and potentially ending with sign
of physiological decompensation .
2.Fetal biophysical parameters can be
affected by factors unrelated to hypoxemia,
such as gestational age, maternal
medication/smoking, fetal sleep-wake
cycles, and fetal disease/ anomalies
EFFICACY – ability to improve pregnancy
outcome has not been evaluated by large,
well designed randomized trails


INDICATION FOR FETAL SURVEILLANCE
1.Diabetes
2.Hypertensive disorder
3.Fetal growth restriction
4.Twin pregnancy
5.Post term pregnancy
6.Decreased fetal activity
7.Systemic lupus erythematosus
8.Antiphospholipid syndrome
9.Sickle cell disease
10.Isoimmunization
11.Oligohydramnios or polyhydramnios
12.Prior fetal demise
13.Preterm premature rupture of membranes
14.Other – nonimmune hydrops, maternal vascular disease,
poorly controlled maternal hyperthyroidism and maternal
vascular disease are associated with an increased risk of
fetal demise and generally considered appropriate
indication for antenantal fetal testing.
1.Fetal Movement counting – objective
maternal assessment of fetal movements is
based on evidence that fetal movement
decreases in response to hypoxemia
2.Contarction stress test – is based on the
fetal response to a transient reduction in
fetal oxygen delivery during uterine
contractions. The fetus becomes
hypoxemic (fetal arterial pO2 below 20mm
Hg), fetal chemoreceptor and
borereceptors, as well as sympathetic and
parasympathetic influences, respond by
reflex slowing of the fetal heart rate (FHR),
which may manifest clinically as late
decelerations.
3. Nonstress test – FHR accelerations, spontaneous or
provoked (e,g by vibroacoustic stimulation), have been
shown to be a good indicator of normal fetal
autonomic function and absence of acidosis and
neurologic depression.
 The main advantage of the NST over the CST is that it does
not require an intravenous line oxytocin, or contractions.
Disadvantages are that the false – negative and falsepositive rates are higher than for the CST (a false – negative
NST is when an antepartum stillbirth occurs within one week of
a reactive test, a false- positive NST is nonreactive test that is
followed by a normal back-up test, such as a negative CST or
high biophysical profile score)
4. Biophysical profile - the biophysical profile (BPP)
combines the NST with ultrasonographic fetal
assessment by assigning points to the following
parameters:
1. Amniotic fluid volume (AFV)
2. Fetal breathing movements
3. Fetal body movements
4. Reflex/tone/flexion-extension movement.
Nonstress test: 2 points if reactive, defined as at least 2 episodes of FHR
accelerations of at least 15 bpm and at least 15 seconds duration from onset
to return associated with fetal movement within a 30-minute observation
period.
Fetal breathing movements: 2 points if one or more episodes of rhythmic
breathing movements of ≥30 seconds within a 30-minute observation period.
Fetal tone: 2 points if one or more episodes of extension of a fetal extremity or
fetal spine with return to flexion.
Amniotic fluid volume: 2 points if a single pocket of fluid is present
measuring at least 2 cm by 1 cm. However, some clinicians use other criteria
such as the amniotic fluid index.
Fetal movement: 2 points if three or more discrete body or limb movements
within 30 minutes of observation. An episode of active continuous movement is
counted as one movement.
The BPP score has a direct linear
correlation with fetal pH the modified
biophysical profile (mBPP) consists of the
NST as a measure of acute oxygenation
and assessment of AFV as a measure of
longer- term oxygenation.
 The false-negative rates for the BPP and
mBPP are very low, but the false- positive
rates are high (a false – negative BPP or
mBPP is when an antepartum stillbirth
occurs within one week of a high score, a
false positive is a low score that is followed
by a normal back – up test.

5.Amniotic fluid volume – in the hypoxemic
fetus, cardiac output is redirected to the
brain,
heart, and adrenals and away from
less vital organs, such as the kidney, the
reduction in renal perfusion leads to
decreased fetal urine production, which may
result in decreased amniotic fluid volume
(oligohydramnious) over time.
 Sonographic determination of the single deepest
amniotic fluid pocket (SDP) is the preferred method
of AFV assessment. The SDP and the amniotic fluid
index (AFI) method are equivalent in their prediction
of adverse outcome in singleton pregnancies, but
use of the AFI increases the number of labor
inductions and caesarean deliveries without any
improvement in perinatal outcome.
6. Doppler velocimetry – provides information about
utroplacental blood flow and fetal responses to
physiological challenges.
1.doppler indices from the umbilical artery
increase when 60 to 70 percent of the placental
vascular tree is compromised.
2. fetal middle cerebral artery impedance falls.
3. fetal aortic resistance rises to preferentially direct
blood to fetal brain and heart.
4. end diastolic flow in the umbilical artery ceases
or reverses and resistance increases in the fetal
venous system (ductus venosus,inferior vena
cava). Umbilical artery Doppler is the most
common Doppler technique used for fetal
assessment where fetal hypoxema is a concern. Fetal
middle cerebral artery – peak systolic velocity is the
best tool for predicting fetal anemia in at-risk
pregnancies.
1.  Umbilical artery - most useful for monitoring
fetuses with early-onset growth restriction due to
uteroplacental insufficiency. Umbilical artery flow
velocity waveforms of normally growing fetuses are
characterized by high- velocity diastolic flow,
whereas in growth-restricted fetuses, umbilical
artery diastolic flow is diminished, absent, or even
reversed in severe cases. In the growth – restricted
fetus absent or reversed end diastolic flow is
associated with fetal hypoxemia and academia,
and increased perinatal morbidity and mortality
►The American college of obstetrics and
gynecologist (ACOG) practice guidelines
support the use of umbilical artery Doppler
assessment in the management of
suspected intra uterine growth restriction,
but not for normally grown fetuses.
2. Middle cerebral artery - the best
tool for monitoring for fetal anemia ssuch
as those affected by rhesus
alloimmunization
3. Fetal veins — Doppler evaluation of
fetal veins combined with umbilical artery
assessment may be useful for predicting
outcomes in growth-restricted fetuses .
The fetal precordial veins (ductus venosus
and inferior vena cava) and the umbilical
vein are the vessels most commonly
evaluated in clinical practice,
4. Uterine artery
1.Impedance to flow in the uterine arteries
normally decreases as pregnancy progresses.
2.Failure of adequate trophoblast invasion and
remodeling of maternal spiral arteries is
characterized by a persistent high-pressure
uterine circulation and increased impedance
to uterine artery blood flow.
3. Elevated resistance indices and/or persistent
uterine artery notching at 22 to 24 weeks of
gestation indicate reduced blood flow in the
maternal compartment of the placenta and have
been associated with development of
preeclampsia, fetal growth restriction, and
perinatal death.

CHOICE OF TEST — The choice depends on
multiple factors:
1.gestational age (up to 50 percent of NSTs are
not reactive in healthy 24 to 28 weeks fetuses
2.availability,
3.desire for fetal biometry or follow-up of a
congenital anomaly,
4.ability to monitor the fetal heart rate (eg, the
NST and CST may not be interpretable in a
fetus with an arrhythmia),
5. cost.
TIMING — Testing should begin as soon as an
increased risk of fetal demise is identified and
delivery for perinatal benefit would be
considered if test results are abnormal.
●DURATION AND FREQUENCY
1.Fetal testing should be performed periodically until
delivery if the clinical condition that prompted fetal surveillance
continues to exist.
2.A single normal test result is adequate if performed for a
nonrecurring indication in an otherwise low-risk pregnancy (eg,
reactive nonstress test after a minor motor vehicle accident and no
signs of labor or vaginal bleeding).
3.Testing is typically performed weekly, but the frequency is
generally increased if there is a change in pregnancy status (eg, fetal
growth percentile falls from 10th percentile to 3rd percentile,
worsening preeclampsia) or in clinical settings considered to be
very high risk (eg, fetal growth restriction with absent or reversed
diastolic flow)
4.There are no data from randomized trials on which to base
recommendations for the optimum frequency of fetal
monitoring (daily, every other day, twice per week, once per
week).
5.These decisions are based on expert opinion, clinical
experience with similar high-risk pregnancies, and community
standards.
●MANAGEMENT OF ABNORMAL TEST RESULTS.
1.Given the high rate of false-positive tests, an abnormal test result is
generally followed by additional testing with a different test (eg,
contraction stress test [CST] or biophysical profile [BPP] after a
nonreactive nonstress test [NST]) to provide more information about fetal
status.
2.The clinical setting to be considered:
(A.)If a temporary maternal condition, such as diabetic
ketoacidosis
or acute bronchospasm, may account for
the abnormal test result,
prompt treatment of the maternal
condition may also improve fetal
oxygenation and lead to
a normal test result on subsequent testing.
(B.)In chronic conditions, clinical judgment guides
management,
taking into account factors such as
gestational age (low threshold
for delivery for an
abnormal test result at term), severity of disease
(eg,
diabetes with poor glycemic control versus good glycemic
control), progression of disease (eg, fetal growth falls
from the 10th
percentile to the 3rd percentile), and other
available information
(eg,
decelerations, absent
variability, or bradycardia on a
nonreactive
NST;
BPP score 0 versus 4 or 6; absence of accelerations
on a
positive CST).
*After a positive CST, up to 40 percent of fetuses have been
reported to tolerate labor without FHR changes necessitating
intervention.