Antepartum fetal monitoring

09.04.2015
1
ANTEPARTUM FETALANTEPARTUM FETAL
MONITORINGMONITORING
Tevfik Yoldemir MD, BBA
Marmara University
Department of Obstetrics and Gynecology
Division of Reproductive Endocrinology and Infertility
ANTEPARTUM FETAL MONITORINGANTEPARTUM FETAL MONITORING
•• Two thirds of fetal deathsTwo thirds of fetal deaths occur before theoccur before the
onset of labor.onset of labor.
•• ManyMany antepartumantepartum deaths occur in womendeaths occur in women
at risk forat risk for uteroplacentaluteroplacental insufficiency.insufficiency.
•• Ideal test: allows intervention before fetalIdeal test: allows intervention before fetal
death or damage from asphyxia.death or damage from asphyxia.
•• Preferable: treat disease process andPreferable: treat disease process and
allow fetus to go to term.allow fetus to go to term.
•• Methods forMethods for antepartumantepartum fetal assessmentfetal assessment
–– Fetal movement countingFetal movement counting
–– Assessment of uterine growthAssessment of uterine growth
–– AntepartumAntepartum fetal heart rate testingfetal heart rate testing
–– Biophysical profileBiophysical profile
–– DopplerDoppler velocimetryvelocimetry
•• Uteroplacental insufficiencyUteroplacental insufficiency
–– Inadequate delivery of nutritive or respiratoryInadequate delivery of nutritive or respiratory
substances to appropriate fetal tissues.substances to appropriate fetal tissues.
–– Inadequate exchange within the placenta dueInadequate exchange within the placenta due
to decreased blood flow, decreased surfaceto decreased blood flow, decreased surface
area or increased membrane thickness.area or increased membrane thickness.
–– Inadequate maternal delivery of nutrients orInadequate maternal delivery of nutrients or
oxygen to the placenta or to problems ofoxygen to the placenta or to problems of
inadequate fetal uptake.inadequate fetal uptake.
•• Theoretical scheme of fetal deteriorationTheoretical scheme of fetal deterioration
–– Fetal well being (Nutritional compromise)Fetal well being (Nutritional compromise)
–– Fetal growth retardation (Marginal placentalFetal growth retardation (Marginal placental
respiratory function)respiratory function)
–– Fetal hypoxia with stress (Decreasing respiratoryFetal hypoxia with stress (Decreasing respiratory
function)function)
–– Some residual effects of intermittent hypoxiaSome residual effects of intermittent hypoxia
(profound respiratory compromise)(profound respiratory compromise)
–– AsphyxiaAsphyxia
–– DeathDeath
•• Conditions placing the fetus at risk for UPIConditions placing the fetus at risk for UPI
–– Preeclampsia, chronic hypertension,Preeclampsia, chronic hypertension,
–– Collagen vascular disease, diabetes mellitus, renalCollagen vascular disease, diabetes mellitus, renal
disease,disease,
–– Fetal or maternal anemia, blood group sensitization,Fetal or maternal anemia, blood group sensitization,
–– Hyperthyroidism, thrombophilia, cyanotic heartHyperthyroidism, thrombophilia, cyanotic heart
disease,disease,
–– Postdate pregnancy,Postdate pregnancy,
–– Fetal growth restrictionFetal growth restriction

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•• Fetal movement countingFetal movement counting
–– Maternal perception of a decrease in fetalMaternal perception of a decrease in fetal
movements may be a sign of impending fetalmovements may be a sign of impending fetal
death.death.
–– It costs nothing.It costs nothing.
–– In a systematic fashion, especially in low riskIn a systematic fashion, especially in low risk
populations, may detect unsuspected fetalpopulations, may detect unsuspected fetal
jeopardy.jeopardy.
•• Fetal movement countingFetal movement counting
–– 3 movements in 30 minutes (Sadovsky).3 movements in 30 minutes (Sadovsky).
–– Elapsed time to register 10 fetal movementsElapsed time to register 10 fetal movements
(Moore and Piacquadio).(Moore and Piacquadio).
•• Assessment of uterine growthAssessment of uterine growth
–– General rule: fundal height in centimeters will equalGeneral rule: fundal height in centimeters will equal
the weeks of gestation.the weeks of gestation.
–– Exceptions: maternal obesity, multiple gestation,Exceptions: maternal obesity, multiple gestation,
polyhydramnios, abnormal fetal lie, oligohydramnios,polyhydramnios, abnormal fetal lie, oligohydramnios,
low fetal station, and fetal growth restriction.low fetal station, and fetal growth restriction.
–– Abnormalities of fundal height should lead to furtherAbnormalities of fundal height should lead to further
investigation.investigation.
–– Accuracy: poor?Accuracy: poor?
•• When to begin testingWhen to begin testing
–– Single factors with minimal to moderateSingle factors with minimal to moderate
increased risk forincreased risk for antepartumantepartum fetal death:fetal death: 3232
weeksweeks..
–– Highest maternal risk factors: 26 weeks.Highest maternal risk factors: 26 weeks.
–– When estimated fetal maturity is sufficient toWhen estimated fetal maturity is sufficient to
expect a reasonable chance of survival shouldexpect a reasonable chance of survival should
intervention be necessary.intervention be necessary.
•• Which test to use?Which test to use?
–– Contraction stress testContraction stress test
•• Low incidence of unexpected fetal deathLow incidence of unexpected fetal death
•• Increase in time, cost and inconvenienceIncrease in time, cost and inconvenience
–– Nonstress testNonstress test
–– Biophysical profile, modified biophysicalBiophysical profile, modified biophysical
profileprofile
–– Doppler velocimetryDoppler velocimetry
•• Nonstress test (NST)Nonstress test (NST)
–– Healthy fetuses display normal oscillations andHealthy fetuses display normal oscillations and
fluctuations of the baseline FHR (Hammacher, 1966;fluctuations of the baseline FHR (Hammacher, 1966;
Kubli, 1969).Kubli, 1969).
–– Absence of these patterns was associated withAbsence of these patterns was associated with
increase in neonatal depression and perinatalincrease in neonatal depression and perinatal
mortality.mortality.
–– Accelerations of the FHR during stress testingAccelerations of the FHR during stress testing
correlated with fetal well being (Trierweiler, 1976).correlated with fetal well being (Trierweiler, 1976).

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3
–– Accelerations of the FHR occur with fetalAccelerations of the FHR occur with fetal
movement, uterine contractions, or inmovement, uterine contractions, or in
response to external stimuli.response to external stimuli.
–– FHR accelerations appear to be a reflection ofFHR accelerations appear to be a reflection of
CNS alertness and activity.CNS alertness and activity.
–– Absence of FHR accelerations seems to depictAbsence of FHR accelerations seems to depict
CNS depression caused by hypoxia, drugs,CNS depression caused by hypoxia, drugs,
fetal sleep, or congenital anomalies.fetal sleep, or congenital anomalies.
–– The endpoint of the NST is the presence or absenceThe endpoint of the NST is the presence or absence
of FHR accelerations within a specified period of time.of FHR accelerations within a specified period of time.
–– Most clinicians use 2 accelerations of 15 beats perMost clinicians use 2 accelerations of 15 beats per
minute (BPM) for 15 seconds in a 20minute (BPM) for 15 seconds in a 20--minute period.minute period.
–– A healthy fetus < 32 weeks’ gestation may not haveA healthy fetus < 32 weeks’ gestation may not have
the reactivity or the accelerations that meet thethe reactivity or the accelerations that meet the
criteria of 15 BPM for 15 seconds.criteria of 15 BPM for 15 seconds.
–– The more remote from term, the more likely thatThe more remote from term, the more likely that
nonreactivity will be due to fetal prematurity.nonreactivity will be due to fetal prematurity.
Basic Features of FH TraceBasic Features of FH Trace
Baseline variability CTGBaseline variability CTG
Baseline variabilityBaseline variability
•• Performing the NSTPerforming the NST
–– External monitors for contraction and FHRExternal monitors for contraction and FHR
measurement applied.measurement applied.
–– Patient in semiPatient in semi--fowler position or left lateralfowler position or left lateral
tilt (to minimize supine hypotension).tilt (to minimize supine hypotension).
–– Fetal movement is recorded.Fetal movement is recorded.
•• Interpreting the NSTInterpreting the NST
–– Reactive: 2 or more accelerations in 20Reactive: 2 or more accelerations in 20
minutes.minutes.
•• Accelerations: an increase of at least 15 BPMAccelerations: an increase of at least 15 BPM
above the baseline lasting at least 15 seconds.above the baseline lasting at least 15 seconds.
–– Fetal sound stimulation may be used to elicitFetal sound stimulation may be used to elicit
a response.a response.

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•• Interpreting the NSTInterpreting the NST
–– Non reactive: Less than 2 accelerations in a 20Non reactive: Less than 2 accelerations in a 20--
minute period.minute period.
•• May extend the testing period to 40 minutes or perform aMay extend the testing period to 40 minutes or perform a
backback--up test.up test.
–– There is no universal agreement on the number ofThere is no universal agreement on the number of
accelerations required to consider the test reactive.accelerations required to consider the test reactive.
–– Reactive/Nonreactive with decelerations: individualizeReactive/Nonreactive with decelerations: individualize
managementmanagement
•• Nonstress testNonstress test
–– Perinatal mortality: 6.2/1000Perinatal mortality: 6.2/1000
–– False positive rate: 50%False positive rate: 50%
–– False negative rate: 3.2 / 1000False negative rate: 3.2 / 1000
www.yoldemir.comwww.yoldemir.com
•• Contraction stress test (CST)Contraction stress test (CST)
–– Uterine contractions producing an intraUterine contractions producing an intra--amnioticamniotic
pressure in excess of 30 mm Hg create an intrapressure in excess of 30 mm Hg create an intra--
myometrialmyometrial pressure that exceeds mean intrapressure that exceeds mean intra--arterialarterial
pressure, therefore temporarily halting uterine bloodpressure, therefore temporarily halting uterine blood
flow.flow.
–– A hypoxic fetus will manifestA hypoxic fetus will manifest late decelerationslate decelerations..
–– Late decelerations correlate with stillbirth, IUGR, andLate decelerations correlate with stillbirth, IUGR, and
lowlow ApgarApgar scores.scores.
–– OxytocinOxytocin challenge test (OCT)challenge test (OCT)
–– Breast (nipple) stimulationBreast (nipple) stimulation
•• How to perform the CSTHow to perform the CST
–– External monitors for contraction and FHRExternal monitors for contraction and FHR
measurement applied.measurement applied.
–– Patient inPatient in semisemi--fowler position or left lateralfowler position or left lateral
tilt (to minimize supine hypotension).tilt (to minimize supine hypotension).
–– Protocol forProtocol for oxytocinoxytocin infusion or breastinfusion or breast
stimulation.stimulation.
–– Goal:Goal: three contractions in ten minutesthree contractions in ten minutes..

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•• Interpretation of the CSTInterpretation of the CST
–– Negative:Negative: no late decelerationsno late decelerations and adequateand adequate
FHR recordingFHR recording
–– Positive: Late decelerations present with thePositive: Late decelerations present with the
majority of contractions (without excessivemajority of contractions (without excessive
uterine activity)uterine activity)
–– Equivocal test results: Suspicious,Equivocal test results: Suspicious,
hyperstimulationhyperstimulation, unsatisfactory., unsatisfactory.
Early Decelerations
Late Decelerations
•• Interpretation of the CSTInterpretation of the CST
–– Suspicious: Late decelerations are present with lessSuspicious: Late decelerations are present with less
than half of the contractions.than half of the contractions.
–– Hyperstimulation: Decelerations after contractionsHyperstimulation: Decelerations after contractions
lasting more than 90 seconds, or with contractionlasting more than 90 seconds, or with contraction
frequency greater than every 2 minutes.frequency greater than every 2 minutes.
–– Unsatisfactory: Cannot induce adequate contractionsUnsatisfactory: Cannot induce adequate contractions
or FHR recording is of poor quality.or FHR recording is of poor quality.
•• Other patternsOther patterns
–– Variable decelerations: considerVariable decelerations: consider
oligohydramnios or cord entrapment.oligohydramnios or cord entrapment.
–– Loss of variability and blunting ofLoss of variability and blunting of
decelerations: ominous sign.decelerations: ominous sign.
–– Sinusoidal pattern: ominous pattern. FetalSinusoidal pattern: ominous pattern. Fetal
anemia or fetalanemia or fetal--maternal hemorrhage.maternal hemorrhage.
–– Nonreactive negative CST: should not occur,Nonreactive negative CST: should not occur,
preexisting CNS abnormality?preexisting CNS abnormality?

09.04.2015
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Variable Decelerations
•• Management of CSTManagement of CST
–– Negative test: repeated weeklyNegative test: repeated weekly
–– Positive test: acted on according to clinicalPositive test: acted on according to clinical
conditioncondition
–– Equivocal test: repeat test the next dayEquivocal test: repeat test the next day
•• When to shorten the interval betweenWhen to shorten the interval between
testingtesting
–– Deterioration in diabetic controlDeterioration in diabetic control
–– Worsening hypertensionWorsening hypertension
–– Need to introduce antihypertensiveNeed to introduce antihypertensive
medicationmedication
–– Decreased fetal movementDecreased fetal movement
•• Contraindications to CSTContraindications to CST
–– PROMPROM
–– Previous classical cesarean deliveryPrevious classical cesarean delivery
–– Placenta previaPlacenta previa
–– Incompetent cervixIncompetent cervix
–– History of premature labor in this pregnancyHistory of premature labor in this pregnancy
–– Multiple gestationMultiple gestation

09.04.2015
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•• Biophysical profile (BPP)Biophysical profile (BPP)
–– Described by Manning (1980)Described by Manning (1980)
–– The number of biophysical activities thatThe number of biophysical activities that
could be recorded increased with real timecould be recorded increased with real time
ultrasound:ultrasound:
•• Fetal movement (FM)Fetal movement (FM)
•• Fetal tone (FT)Fetal tone (FT)
•• Fetal breathing movements (FB)Fetal breathing movements (FB)
•• Amniotic fluid volume (AFV)Amniotic fluid volume (AFV)
•• Biophysical profile (BPP)Biophysical profile (BPP) –– variablesvariables
–– NST: reactiveNST: reactive –– as described earlier.as described earlier.
–– FBM: presentFBM: present -- at least 1 episode of at least 30at least 1 episode of at least 30
seconds duration (within a 30 minute period).seconds duration (within a 30 minute period).
–– FM: presentFM: present -- at least 3 discrete episodes.at least 3 discrete episodes.
–– FT: normalFT: normal -- at least 1 episode of extension ofat least 1 episode of extension of
extremities or spine with return to flexion.extremities or spine with return to flexion.
–– AFV: normalAFV: normal –– largest pocket of fluid greater than 1largest pocket of fluid greater than 1
cm in vertical diameter.cm in vertical diameter.
–– Each variableEach variable
•• When normal: 2When normal: 2
•• When abnormal: 0When abnormal: 0
–– Highest Score: 10, Lowest Score: 0Highest Score: 10, Lowest Score: 0
–– Accuracy improved by increasing the numberAccuracy improved by increasing the number
of variables assessed.of variables assessed.
–– Overall false negative rate: 0.6/1000Overall false negative rate: 0.6/1000
–– Acute markers of fetal compromise: NST, FT,Acute markers of fetal compromise: NST, FT,
FBM, FMFBM, FM
–– Chronic marker of fetal compromise: AFVChronic marker of fetal compromise: AFV
–– Nervous impulses that initiate fetal biophysicalNervous impulses that initiate fetal biophysical
activities arise from different anatomic sitesactivities arise from different anatomic sites
within the brain.within the brain.
–– Activities that become active first in fetalActivities that become active first in fetal
development (development (FTFT,, FMFM) are the last to) are the last to
disappear when asphyxia arrests all activities.disappear when asphyxia arrests all activities.
–– Activities that become active later in gestationActivities that become active later in gestation
((NSTNST,,FBMFBM) will be abolished 1) will be abolished 1stst in cases ofin cases of
hypoxia and acidosis.hypoxia and acidosis.

09.04.2015
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–– Fetal tone: 7.5 to 8.5 weeksFetal tone: 7.5 to 8.5 weeks
–– Fetal movement: 9 weeksFetal movement: 9 weeks
–– Fetal breathing: 20 to 21 weeksFetal breathing: 20 to 21 weeks
–– NST: 24 to 28 weeksNST: 24 to 28 weeks
–– When hypoxia and acidosisWhen hypoxia and acidosis
•• Late decelerations appear (CST)Late decelerations appear (CST)
•• Accelerations disappear (CST, NST, BPP)Accelerations disappear (CST, NST, BPP)
•• Fetal breathing stops (BPP)Fetal breathing stops (BPP)
•• Fetal movement ceases (BPP, FMC)Fetal movement ceases (BPP, FMC)
•• Fetal tone absent (BPP)Fetal tone absent (BPP)
–– Assessment of fetal wellAssessment of fetal well--being in high riskbeing in high risk
pregnanciespregnancies
•• Reduced perinatal mortality rate from 65/1000 to 5/1000Reduced perinatal mortality rate from 65/1000 to 5/1000
•• BPP and perinatal mortality (PNMR)BPP and perinatal mortality (PNMR)
–– 12,000 pregnancies (Manning, 1985)12,000 pregnancies (Manning, 1985)
–– BPP Score Corrected PNMRBPP Score Corrected PNMR
•• 88--10 0.610 0.6
•• 6 0.06 0.0
•• 4 22.04 22.0
•• 2 42.62 42.6
•• 0 187.00 187.0
–– When the FHR accelerates, there is virtuallyWhen the FHR accelerates, there is virtually
always fetal movement (FM)always fetal movement (FM)
–– If the NST is reactive, there is fetal movementIf the NST is reactive, there is fetal movement
(FM) and tone (FT)(FM) and tone (FT)
–– If the NST is reactive, do not need theIf the NST is reactive, do not need the
ultrasound parameters of the BPPultrasound parameters of the BPP
–– Only the AFV would add additionalOnly the AFV would add additional
informationinformation
•• Modified biophysical profile (BPP)Modified biophysical profile (BPP)
–– A standard NST is combined with an amniotic fluidA standard NST is combined with an amniotic fluid
index (AFI)index (AFI)
–– Negative: Reactive NST / AFI > 5.0 cmNegative: Reactive NST / AFI > 5.0 cm
–– If NST is nonreactive or has decelerations, or if theIf NST is nonreactive or has decelerations, or if the
AFI isAFI is << 5.0 cm, then a BPP is performed.5.0 cm, then a BPP is performed.
–– Negative results are repeated every 3 to 4 days.Negative results are repeated every 3 to 4 days.
–– If the AFI > 5.0 cm, a repeat AFI may be done in oneIf the AFI > 5.0 cm, a repeat AFI may be done in one
week.week.

09.04.2015
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•• Primary fetal surveillancePrimary fetal surveillance
–– There have been no adequate prospectiveThere have been no adequate prospective
randomized studies comparing the various testingrandomized studies comparing the various testing
modalities.modalities.
–– The final decision regarding choice of fetalThe final decision regarding choice of fetal
surveillance test is most often determined bysurveillance test is most often determined by
institutional preference and experience.institutional preference and experience.
–– All forms of fetal testing are valuable and need to beAll forms of fetal testing are valuable and need to be
interpreted cautiously with full knowledge of theinterpreted cautiously with full knowledge of the
specific test limitations.specific test limitations.
•• Primary fetal surveillancePrimary fetal surveillance
–– NST: The most popular methodNST: The most popular method
•• Easy to perform, easy to interpret, has fewerEasy to perform, easy to interpret, has fewer
equivocal results, has excellent patient andequivocal results, has excellent patient and
physician acceptance.physician acceptance.
•• BPP as a back up test.BPP as a back up test.
–– BPP:BPP:
•• Can identify oligohydramnios and anomalousCan identify oligohydramnios and anomalous
babies.babies.
•• Antepartum death rate is less than with the NST.Antepartum death rate is less than with the NST.
•• Doppler velocimetry of the umbilical arteriesDoppler velocimetry of the umbilical arteries
–– 40% of combined ventricular output is directed to the40% of combined ventricular output is directed to the
placenta by umbilical arteries.placenta by umbilical arteries.
–– Assessment of umbilical blood flow providesAssessment of umbilical blood flow provides
information on blood perfusion of the fetoplacentalinformation on blood perfusion of the fetoplacental
unit.unit.
–– Volume of flow increases and vascular impedanceVolume of flow increases and vascular impedance
decreases with advancing gestational age.decreases with advancing gestational age.
–– Low vascular impedance allows a continuous forwardLow vascular impedance allows a continuous forward
blood flow throughout the cardiac cycle.blood flow throughout the cardiac cycle.
•• Doppler velocimetryDoppler velocimetry
–– An increase in the vascular resistance of theAn increase in the vascular resistance of the
fetoplacental unit leads to a decrease in end diastolicfetoplacental unit leads to a decrease in end diastolic
flow velocity or its absence in the flow velocityflow velocity or its absence in the flow velocity
waveform.waveform.
–– Abnormal waveforms reflect the presence of aAbnormal waveforms reflect the presence of a
structural placental lesion.structural placental lesion.
–– Abnormal Doppler results require specificAbnormal Doppler results require specific
management protocols and intensive fetalmanagement protocols and intensive fetal
surveillance.surveillance.
•• Doppler velocimetryDoppler velocimetry
–– A poor indicator of fetal compromise orA poor indicator of fetal compromise or
adaptation to the placental abnormality butadaptation to the placental abnormality but
does identify patients at risk for increaseddoes identify patients at risk for increased
perinatal mortality.perinatal mortality.
–– Strong association between high systolic toStrong association between high systolic to
diastolic ratios and IUGR.diastolic ratios and IUGR.
ThankThank youyou forfor youryour attentionattention..

Antepartum fetal monitoring

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