ANTEPARTUM
ASSESSMENT
CONTENTS
Fetal movements
II. Fetal breathing movements
III. Contraction stress test
IV. Non-stress test
V. Biophysical profile
VI. Amnionic fluid volume
VII. Umbilical Artery Doppler Velocimetry
Current recommendations
Significance of fetal testing
I.
INTRODUCTION
- In the 1st William obstetric edition 1903:
FHR > 160 b/m or < 100 b/m is dangerous
- Now the fetus is considered as a 2nd patient
and exposed to serious morbidity and
mortality > his mother
- Fetal testing is now extended to the
embryonic life:
e.g. Embryonic HR may predict pregnancy
outcome
Our goal is to prevent fetal death
Fetal death within 7 days of a normal
test is very rare
In most tests:
+ve predictive value (true +ve) = 99.8%
--ve predictive value of abnormal tests
(true –ve) = 10 – 40%
FETAL MOVEMENTS
- FMs starts at 7th week
- At 8th week  FMs are never
absent > 13 minutes
- At 20 – 30 weeks  organization
of FMs ( rest - activity cycles)
- In the 3rd trimester until 36 weeks
 maturation of FMs
- > 36 weeks  behavioral states
BEHAVIORAL STATES
FHR
FMs
1F quite sleep
vvvvvv
no
2F active sleep
VVVVV
I
3F
VVVVV
no
4F awake state
VVVVV
IIIIII
+ FHR accelerations
The presence of F3 is debate
Continuous eye movements are present
in: 2F, 3F, 4F
At 38 weeks 75% of the time 1F&2F
Study:
Urinary bladder ↑ in 1F and ↓ in 2F
Sleep – awake cycles:
Sleep  20 - 75 minutes
Mean = 23 minutes
Maternal perception of FMs is
described as: weak - strong - rolling
FMs is α to AFV:
As GA ↑ > 20 weeks
 weak FMs ↓
vigorous FMs ↑
> 32 weeks strong FMs ↓ due to:
 ↓ AFV
 ↓ space
Normal FMs:
= 4 – 10 FMs / 12 hours
In 1973  ↓ FM precede fetal death
Methods of measuring FMs:



Tocodynamometer
U/S
Maternal perception
Study:
Maternal perception = 80% of FMs by U/S
Study:
- > 36 weeks, maternal perception = 16%
- Longer FMs > 20 seconds are better felt
Optimal number and duration of FMs:
Not defined
Study:
Normal FMs = 10 FMs/2 hours
Study:
FM/1 hour is good if ≥ previous count
Patient complaint of ↓ FMs in the 3rd T:
Not uncommon = 7%  same pregnancy
outcome  Evaluate & reassure
NST is indicated if:


Abnormal fetal growth by U/S
Abnormal Doppler
Study:
Mean duration to record 10 FMs
= 2.7 hours of counting/day
Study:
Asking mothers about FMs each
visit = counting FMs
II - BREATHING MOVEMENTS
In 1972  inward and outward flows
of tracheal fluid in sheep = BMs
BMs differ from FMs:
 Paradoxical = inspiration collapse
expiration distend
 Not continuous
May be coughing to expel AF debris
Essential for fetal development
Types of BMs:
 Gasps/sighs = 1 - 4/minute
 Irregular bursts = up to 240c/m
As GA ↑  BMs rate ↓ & volume ↑
At 33 – 36 weeks = lung maturation
30 - 40 weeks  diurnal variation:
 ↑ after meals
 ↓ at night
If BMs are not seen
extend U/S evaluation for up to 2
hours before diagnosis of absent BMs
Factors affecting BMs:
Hypoxia
Sound
Hypoglycemia
Cigarette
Labor
FHR
Impending PTL
GA
Amniocentesis
BMs as a marker of fetal wellbeing:
Unfulfilled because multiple factors it
affect it, but it is included in BPP with
Other indices
IV - CONTRACTION
STRESS
TEST
Basis:
Uterine contractions
 ↑ amnionic fluid P
 collapse of uterine vessels
 isolation of intervillous space
 transient ↓ O2 exchange
If uteroplacental pathology is present
 late decelerations
CST is present since 1972
Late decelerations:
Start at/or beyond the acme of uterine
contraction
Disadvantages:
Require 1 ½ hours
Method:
Oxytocin 0.5 mIU/minute by infusion pump
doubled /20 minutes  3 contractions in
10 minutes duration of each ≥ 40 seconds
Nipple stimulation:
1 nipple is rubbed through her clothes for
2 minutes or until contractions start, restart
After 5 minutes  3 contractions in 10 min
Advantages: ↓ time and cost
May  hyperstimulation with mild FD
CRITERIA FOR INTERPRETATION OF CST
Negative: No LD or significant VD
Positive: LD + 50% of contractions even
if contractions are < 10/m
Equivocal-suspicious:
 Intermittent LD
 Significant VD
Equivocal-hyperactive:
 LD + > 3 contractions/10m
 Contraction > 90 seconds
Unsatisfactory:
 < 3 contractions /10m
 Uninterruptable tracing
VI – NONSTRESS TEST
1975
Basis:
FMs  FHR accelerations = good sign
Equipments:
 Doppler
 Maternal perception of FMs
Differ from CST and much easier
Used to discriminate false +ve CST
Used in BPP
Physiology:
Beat to beat variability > 5 b/m + FHR
accelerations = good autonomic function
Most common causes of no accelerations:
 Fetal sleep
 Drugs
As GA ↑  ↑ FMs + ↑ FHR accelerations
25 – 28 weeks accelerations are
70% 15 b/m for 15 seconds
90% 10 b/m for 10 seconds
< 32 weeks use 10 b/m for 10 seconds
Normal NST:
Vary in number, amplitude & duration
of acceleration
= ≥ 2 accelerations that peak at ≥ 15 b/m
for ≥ 15 seconds in 20 minutes ± FM
1 acceleration is enough by some
If no accelerations  extend examination
to 40-75-80-120 minutes before diagnosis
of nonreactive NST
No accelerations = not bad fetus
False +ve NST ≥ 90%
Disadvantages of NST:
 ↑cost
 Irreducibility
Computerized analysis:
 ↓ cost
 Reliable
 objective
Abnormal NST:
- Silent oscillatory pattern = ominous
= beat - to - beat variability < 5 b/m
+ no accelerations
- Terminal cardiogram:
Both + LD
= uteroplacental insufficiency
Abnormal NST is associated with:
FGR
75%
Oligohydramnios
80%
Acidosis
40%
Meconium
30%
Placental infarction 93%
Study:
Nonreactive NST for ≥ 90 min is
associated with ↑ perinatal
pathology in 93%
Interval between tests:
1/week
2/week, 1/day, > 1/day in:
 Postterm
 Type 1 DM
 FGR
 PIH
Decelerations:
Normally present in ½ to 2/3 of fetuses
Variable decelerations:
Not ominous if nonrepetitive and brief
< 30 seconds
Repetitive VD ≥ 3 /20 minutes even if
mild are associated with ↑ CS for FD
Decelerations ≥ 1 min  bad prognosis
Study:
- Addition of NST to AFV  75% CS for
FD in cases of ↑ VD + ↓ AFV
- FD in labor + normal AFV is increased
in patients with VD
False - normal NSTs:
= fetal death within 7 days of a
normal NST
Mean interval between testing
and death: = 4 days
Range:
= 1 - 7 days
Most common indication of NST:
= postterm
Most common autopsy findings:

Meconium

Abnormal umbilical cord
= Acute asphyxial insult
= NST is inadequate to preclude
such an acute asphyxial events
Other causes:
 Fetomaternal Hg
 Infection
 Abruptoplacenta
 Congenital anomalies
 Abnormal cord insertion
Acoustic Stimulation Tests:
Artificial larynx  acoustic stimulation
to ↑ acceleration
Method:
External sound for 1 – 2 seconds
Repeat 1 – 3 times for up to 3 seconds
Still under evaluation
VII – BIOPHYSICAL PROFILE
Manning & colleagues 1980
5 variables to ↓ false +ve
↓ false –ve results
Equipments:
 Doppler
 Real time U/S
Duration of testing:
1/2 – 1 hour
2
0
NST
≥ 2 accelerations
<2
(≥15 b/m for ≥15 sec in 40 minutes)
FBMs ≥ 1 ≥ 30 sec in 30 m < 30 sec
FMs
≥ 3 in 30m
<3
F Tone
≥1
-AFV
> 2 cm
≤ 2 cm
( largest single vertical
pocket)
Fetal tone = flexion and extension of
one limb or opening or closing hand
NST is not required if the 4 variables
are normal
AFI if the largest vertical pocket is ≤ 2
cm  should be evaluated
BPP = 6 is equivocal and poor predictor
of abnormal outcome
BPP = < 6 is progressively more accurate
predictor of abnormal outcome
Study:
BPP followed by cordocentesis for pH:
- 20% of fetuses are FGR
- 80% of fetuses have alloimmune
hemolytic anemia
BPP = 0 is associated with acidemia
BPP = 8 - 10 is associated with
normal pH
Study:
BPP+cordiocentasis in DMno benefit
Study:
BPP+cordiocentasis in GRno benefit
The morbidity and mortality in GR
depend on GA & wt not BPP results
Modified BPP( abbreviated BPP 1989):
= vibroacoustic NST + AFV X 2/week
Duration of testing = 10 minutes
If AFV is < 5 do complete BPP or CST
CST ↑CS for false abnormal results
Acceptable by ACOG
False –ve rate = 0.8 : 1000
False +ve rate = 1.5 : 1000
Study:
Excellent method with no unexpected
FD
MODIFIED BPP MANAGEMENT
BPP = 10:
 Repeat 1/w
2/w in DM & postterm
BPP = 8 -10 + normal AFV:
 Repeat
BPP = 8 -10 + ↓ AFV:
Chronic fetal asphyxia suspected
 Deliver
BPP = 6:
Possible fetal asphyxia
If > 36 weeks + normal AFV +
favorable cervix  deliver
If < 36 weeks + normal AFV
 repeat:
if ≤ 6  deliver
if > 6  repeat
If + ↓ AFV  deliver
BPP = 4:
Probable fetal asphyxia
 repeat same day
if ≤ 6  deliver
BPP = 0 - 2:
Almost certain fetal asphyxia
 deliver
VIII – AMNIONIC FLUID
VOLUME

Basis:
Uteroplacental insufficiency
 ↓ fetal renal blood flow
 ↓ urine production
 ↓ AFV
Methods:
 AVI
 Largest vertical pocket
 2 x 2 cm pocket
Study:
AFI < 5 cm 
↑ CS for FD
↑ low 5 minutes Apgar score
↑ perinatal morbidity & mortality
Study:
20% of fetuses have AFI < 5 cm
AFI = poor diagnostic test
Study:
Same results in severe preeclampsia
Study:
Nonintervention to permit spontaneous
VD in fetuses with AFI < 5
 same pregnancy outcome as
induction of labor
IX – UMBILICAL ARTERY
DOPPLER VELOCIMETRY
Basis:
To assess blood flow by characterizing
downstream impedance
Uterine artery S/D ratio:
Most commonly useded, abnormal if:
- ↑ 95th percentile for GA
- Diastolic flow is:
Absent (perinatal mortality = 10%)
Reversed (perinatal mortality = 33%)
Both absent and reversed diastolic
flow are associated with IUGR
Study:
NST = Doppler
Study:
No benefit other than suggesting GR
Study:
No benefit in other diseases as: PIH,
DM, lupus anticoagulant, postterm
Middle cerebral artery S/D ratio:
May reflect fetal compromise
Based on brain sparing theory:
= uteroplacental insufficiency
↑ blood flow + ↓ impedance
Study:
No significant difference
Still under evaluation
CURRENT
RECOMMENDATIONS
No agreement for the best test
All tests have different end points that are
considered according to the clinical situation
When to start?
Most important considerations in deciding
when to start:
 Prognosis of neonatal survival
 Severity of maternal disease
In high risk patients at 32 – 34 weeks
In more severe cases at 26 – 28 weeks
Frequency of testing: ≥ 1/week
In parkland hospital:
All high risk patients are admitted
NST 2 – 3/week for admitted cases
If FHR accelerations + Deceleration
 No need for delivery
If ↓ FMs or ↓ AFV in 3rd T
 Admission in labor suit
According to results of NST the patient is:
 Discharged
 Transformed to high risk ward
 Delivered
Fetal deaths in high risk patients are low
Most fetal deaths are in low risk patients
due to unpreventable events as:
 Placental abruptions
 Cord accidents
SIGNIFICANCE OF
TESTING
Does it make any difference?
Fetal surveillance in 1970s = < 1%
in 1980s = 15%
Fetal death rate ↓ in high risk tested
patients # untested patients
Study:
NSTs/CSTs are not recommended
because of ↑ cost
Study:
No benefit of testing  forms of care
likely to be ineffective or harmful
Can we identify fetal asphyxia early
enough to prevent brain damage?
Study:
Abnormal NST is associated with ↓
cognition # Doppler = by the time
fetal compromise is diagnosed,
brain damage is already sustained
Study:
CP in high risk patients managed
by BPP = 1.3 : 1000 live birth
# 4.7 : 1000 in controls
In a prior report:
CP is associated with ↓ BPP scores
= identification is too late
SUMMERY
In the last 2 decades:
- Methods are continuously evolving
= dissatisfaction
- Wide range of normal variables:
How many accelerations–FMs–FBMs
duration and frequency of testing
- Abnormal results are seldom reliable
= forecast fetal wellness rather
than illness