This document provides an overview of fetal surveillance techniques used in antepartum and intrapartum periods. In the antepartum section, it discusses various risk factors for fetal death and different testing modalities used for surveillance including maternal fetal movement assessment, contraction stress testing, non-stress testing, biophysical profile, Doppler velocimetry, and their predictive values. The intrapartum section covers the physiological basis for fetal heart rate monitoring during labor, different monitoring methods like intermittent auscultation and continuous electronic monitoring, and parameters assessed from the monitoring including baseline rate, variability, accelerations, and decelerations.
3. Introduction
• Assessment of fetal wellbeing in ante-partum
and intrapartum period to ensure delivery of
healthy neonate.
• Fetus responds to chronic hypoxemia with a
detectable sequence of biophysical changes,
beginning with signs of physiological
adaptation and potentially ending with signs
of physiological decompensation.
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4. Introduction cont.…
59% of all perinatal deaths in developed nations were found to be avoidable
Of the above 74% of cases were of normal weight and with no fetal anomalies or maternal
complications.
The failure to respond appropriately to abnormalities during pregnancy and labor including
results from the monitoring of fetal growth or intrapartum fetal well-being, significant
maternal weight loss, or reported reductions in fetal movement constituted the largest
groups of avoidable factors.
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6. “ The goal of evidence-based antepartum fetal evaluation is to decrease perinatal mortality and
permanent neurologic injury through judicious use of reliable and valid methods of fetal
assessment without acting prematurely to modify an otherwise-healthy pregnancy or providing a
false sense of well-being in cases of impending morbidity. ”
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7. Introduction
• Identification of fetuses at risk for perinatal mortality is the goal of antepartum fetal
assessment.
• Perinatal events play a significant role in infant mortality accounting for 50% of infant mortality
in 2010 in the US.
• Antepartum fetal death is much more common than intrapartum fetal death.
• Antepartum deaths may be divided into four major categories:
(1) chronic asphyxia of diverse origin (30%);
(2) congenital malformations (15%);
(3) superimposed complications of pregnancy (30%),
(4) deaths of unexplained cause (20%)
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9. Risk factors of fetal death
• Gestational age
• Maternal age
• Socioeconomic factors and substance use
• Obesity
• Diabetes mellitus
• Intrahepatic cholestasis
• Renal disease in the mother
• SLE
• Fertility history and ART
• Multiple gestation
• Early pregnancy markers
• Post term pregnancy
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10. Utility of antepartum testing
Before using antepartum fetal testing, the physician must ask several important questions:
1. Does the test provide information not already known by the patient’s clinical status?
2. Can the information be helpful in managing the patient?
3. If an abnormality is detected, is a treatment available for the problem?
4. Could an abnormal test result lead to increased risk for the mother or fetus?
5. Will the test ultimately decrease perinatal morbidity and mortality?
The best use of available antenatal testing modalities may vary
according to the risk profile of each individual pregnancy.
In interpreting the results of studies of antepartum
testing, the physician must consider the application of
that test to his or her own population.
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11. Modes of Antepartum assessment
1. Maternal assessment of Fetal movement
2. Contraction stress testing
3. Non-stress testing
4. Biophysical profile/ Modified biophysical profile
5. Doppler velocimetry
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12. Fetal states
Four fetal behavior states as described by Nijhuis & colleagues (1982) based on fetal
movements, fetal heart rate & eye movements :-
1. State 1F- Quiescent state- quiet sleep with narrow oscillatory bandwidth of FHR.
2. State 2F- Frequent gross body movements, cont. eye movements, wider oscillations of fetal heart
rate. (=REM of neonate)
3. State 3F- Continuous eye movements in absence of body movements and heart rate accelerations.
The existence of such state is doubtful
4. State 4F- Vigorous body movements with constant eye movements and FHR accelerations
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13. 1. Maternal assessment of fetal activity
During the 3rd trimester a fetus spends 10% of its time moving and 30 such movements are made
each hour.
Mothers are able to perceive 70-80% of such movements.
There are a variety of proposed thereshholds defining normal fetal movement.
Degree of fetal movement is affected by;
• Glycemic state of the mother
• Hypoxia
• Music
• Time of the day
In addition factors like location of the placenta, amount of amniotic fluid and the length and type
of fetal movements affect the maternal perception of fetal movement.
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14. Maternal assessment of fetal activity
A 2007 literature review of four trials that involved more than 71,000 women concluded that
evidence is insufficient to recommend routine FMC to prevent fetal death.
Potential negative impacts of maternal assessment of fetal activity include maternal anxiety
and a potential increase in utility of other testing modalities and antepartum admissions.
Yet since there is some evidence indicating Fetal movement monitoring does reduce fetal
death risk when compared to no monitoring mothers should be advised to stay vigilant for
“significant and persistent reduction in fetal movement. ”
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15. 2. Contraction stress testing
• Also known as the oxytocin challenge test (OCT).
• The response of the fetus at risk for uteroplacental insufficiency to uterine contractions forms
the basis for this test
Uterine contraction = amniotic fluid pressure = Blood flow to the intervillous space
• Fetal heart rate is recorded at base line and during uterine contractions of moderate intensity
that last about 40 to 60 seconds with a frequency of three in 10 minutes.
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18. Contraction Stress Test (Predictive Value)
• A negative CST has been consistently associated with good fetal outcome.
• If the CST is negative and reactive, a repeat study is usually scheduled in 1 week.
• A negative nonreactive CST is usually repeated in 24 hours.
• A positive CST has been associated with an increased incidence of intrauterine death, late
decelerations in labor, low 5-minute Apgar scores, IUGR, and meconium stained amniotic fluid
with an overall likelihood of perinatal death after a positive CST ranging from 7% to 15%.
• The positive CST is more likely to be associated with fetal compromise if the baseline heart rate
lacks accelerations and the latency period between the onset of the uterine contractions and
the onset of the late deceleration is less than 45 seconds.
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19. Contraindication to CST
After the CST has been completed, the patient should be observed until uterine activity has
returned to its baseline level.
Contraindications include;
• PROM,
• multiple gestations
• cervical incompetence,
• placenta Previa
• previous classic cesarean delivery
• uterine surgery.
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20. 3. Non-stress test
In late gestation, the healthy fetus exhibits an average of 34 accelerations above the baseline
fetal heart rate each hour.
These accelerations, which average 20 to 25 beats/min in amplitude require intact neurologic
coupling between the fetal CNS and the fetal heart.
The above connection is disrupted by hypoxia and forms the basis for NST.
The NST is usually performed in an outpatient setting.
The fetal heart rate is monitored using the Doppler ultrasound transducer, and the
tocodynamometer is applied to detect uterine contractions or fetal movement.
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21. Observable Patterns on NST (Reactive)
At least two accelerations of the fetal heart rate, each with a peak amplitude of 15 beats/min
and total duration of 15 seconds, observed in 20 minutes of monitoring
Threshold is different for different gestational ages because of differences in autonomic
innervation.(increased frequency and amplitude of fetal heart rate accelerations are seen
after 30 weeks of gestation)
Therefore before 30 to 32 weeks’ gestation, acceptable criteria for a reactive fetal heart rate
tracing include accelerations with a peak of only 10 beats/min amplitude and 10 seconds’
duration
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22. Observable Patterns on NST
(Non-Reactive)
• If the criteria for reactivity are not met, the test is considered nonreactive.
• The most common cause for a nonreactive test is a period of fetal inactivity or quiet sleep.
• Extending the test for another 20 min, VAS or retesting later in the day may change results
while manual stimulation or attempts to increase blood glucose are of no proven benefit.
• If the test has been extended for 40 minutes, and reactivity has not been seen, a BPP or CST
should be performed.
** Most fetuses that exhibit a nonreactive NST are not compromised but simply fail to exhibit
heart rate reactivity during the 40-minute period of testing.
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23. Other Nonstress Test Patterns
SINUSOIDAL PATTERN
Undulating heart rate pattern with virtually
absent variability.
associated with fetal anemia and asphyxia,
congenital malformations, and medications
such as narcotics.
In one small series only 10% of the babies with
a sinusoidal pattern had an uncomplicated
course.
BRADYCARDIA
Defined as a fetal heart rate of 90 beats/min or a
fall in the fetal heart rate of 40 beats/min below
the baseline for 2 minutes or longer.
associated with antepartum fetal death, cord
compression, IUGR, and fetal malformations.
If bradycardia is observed, an ultrasound
examination should be performed to assess
amniotic fluid volume and to detect the
presence of anomalies.
Expectant management in the setting of a
bradycardia has been associated with a PMR of
25%.
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24. Other Nonstress Test Patterns
TACHYCARDIA
• The most common etiology of fetal
tachycardia is maternal-fetal fever secondary
to maternal-fetal infectionsuch as
chorioamnionitis
• Other causes include chronic hypoxemia,
maternal hyperthyroidism, and fetal
tachyarrhythmia.
• Fetal heart rates above 200 beats/min, should
increase the index of suspicion of fetal
tachyarrhythmia and lead to further fetal
cardiac evaluation with a targeted fetal
echocardiogram.
ARRHYTHMIA
• Approximately 90% are tachyarrhythmia's.
• Diagnosed when the fetal ventricular heart
rate is faster than 180 beats/min.
• Common causes of fetal tachyarrhythmias
are paroxysmal supraventricular tachycardia
and atrial flutter.
• Fetal bradyarrhythmia is diagnosed when the
fetal ventricular heart rate is slower than 100
beats/min, mainly because of atrioventricular
block.
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25. NST (predictive value)
The NST is most predictive when it is normal or reactive.
The reported false-negative rate ranges from 0.2% to 0.8%.
The false-positive rate is considerably higher and ranges from 50% to more than 90%.
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26. 4. Fetal biophysical profile
The use of real-time ultrasonography to assess antepartum fetal condition
The profile is based in five parameters;
• Fetal breathing movments
• Gross body/limb movments
• Fetal tone
• Reactive fetal heart rate
• Amniotic fluid volume
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28. Biophysical profile cont….
The BPP may be used as early as 26 to 28 weeks’ gestation.
The time required for the fetus to achieve a satisfactory BPP score is closely related to fetal
state, (average 5 minutes in 2F state but over 25 minutes in 1F state).
Some studies have demonstrated that antenatal corticosteroid administration may have an
effect on the BPP, decreasing the profile score.
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29. BPP (predictive value)
The false negative rate of a normal BPP is less than 0.1%, or less than 1 fetal death per 1000
within 1 week of a normal BPP.
The false-positive rate of a score of 0 is less than 20%, but for a score of 6, it is up to 75%.
In one study no perinatal deaths were observed when all five variables described earlier were
normal, but a PMR of 60% was seen in fetuses with a score of zero.
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30. Modified BPP
• In an attempt to simplify and reduce the time necessary to complete testing, a variety of
modifications were made to create the modified BPP.
• The NST, an indicator of present fetal condition, was combined with assessment of AFV (via
DVP), a marker of long-term status,
• MBPP is as good a predictor of adverse fetal outcome as a negative CST.
• The MBPP has a false positive rate comparable to that of the NST but higher than that of the
CST and full BPP.
• It an excellent approach for the evaluation of large numbers of high-risk patients.
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31. Doppler sonography
• Noninvasive assessment of the fetal, maternal, and placental circulations.
• This method of fetal assessment has only been demonstrated to be of value in reducing
perinatal mortality and unnecessary obstetric interventions in fetuses with suspected IUGR and
possibly other disorders of uteroplacental blood flow.
• Considered as a follow-up test to determine fetal reserve in cases of suspected IUGR and not as
a primary method of antenatal fetal surveillance for either high- or low-risk pregnancies.
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33. Clinical application of antepartum
fetal well being
• The approach to prescribing testing modalities must take into account gestational age, medical
comorbidities, and sociodemographic risk factors in order to avoid iatrogenic prematurity or an
excess of testing and worry.
• Parallel and branched schemes can be used depending on the maturity of the fetus and the risk
of intervention.
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35. Introduction
• Normal labor: regular uterine contraction and transient interruption of fetal oxygenation.
• Rationale Intrapartum assessment:
◦ identification of FHR changes potentially associated with inadequate fetal oxygenation may enable
timely intervention to reduce the likelihood of hypoxic injury (asphyxia induced brain damage) or
death.
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36. Physiologic basis for FHR monitoring
• FHR monitoring in real sense is fetal brain monitoring
• Indirect markers of the fetal cardiac and medullary responses to blood volume changes,
acidemia, and hypoxemia
• Fetal brain responds to hypoxia by altering FHR
• Many factors other than oxygenation will cause the brain to alter FHR or may affect the fetal
heart directly
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37. Modes of surveillance
INTERMITTENT AUSCULTATION
No risk factors
◦ Every 30 minutes, Active phase of 1st stage
◦ Every 15 minutes, During 2nd stage
Risk factors
◦ Every 15 minutes, Active phase of 1st stage
◦ Every 5 minutes, During 2nd stage
CONTINUOUS ELECTRONIC MONITORING
• Continuous recording & graphical
representation of FHR & uterine contractions
• EFM-externally or internally
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38. Parameters assessed
• Baseline rate
• Baseline FHR variability
• Presence of FHR accelerations
• Periodic or episodic FHR decelerations
• Change or trends of FHR patterns over time
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40. Base line rate
Base line FHR - is the mean FHR rounded to increment of 5bpm during a 10 minute segment
without periodic or episodic change,
Tachycardia - baseline rate above 160 bpm
◦ Mild 160-180bpm
◦ Severe ≥ 181
Bradycardia- Base line FHR < 120 bpm
◦ Mild 100-119bpm
◦ Moderate 80-100bpm
◦ Severe<80bpm
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42. Variability
Differences in heart rate from beat to beat reflected visually as a line that
fluctuates above and below the baseline
The most useful single parameter in determining severity of hypoxia
Is a reflection of an intact and active CNS and normal cardiac responsiveness.
*** Cause of minimal or absent FHR variability includes; Fetal Hypoxia, Narcotics, Magnesium
Sulfate, Congenital Anomalies, Fetal Sleep Cycles, Extreme Prematurity, Preexisting Neurologic
injury
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43. Decelerations
Four principal type based on timing, relationships to contractions , duration and
shape
Early deceleration
Late deceleration
Variable deceleration
Prolonged deceleration
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44. Decelerations continued
EARLY DECELERATION
Gradual (onset to nadir ≥30 sec) decrease in FHR during a uterine
contraction.
Onset, nadir, and recovery of the deceleration occur at the same
time as the beginning, peak, and end of the contraction,
respectively.
Caused by fetal head compression leading to a vagal response
Presumed to be benign not associated with fetal hypoxia or
acidosis
No intervention is required
Uncommon during active labor.
LATE DECELERATION
Decrease in FHR is gradual (onset to nadir ≥30
sec) during a uterine contraction.
Deceleration occur after the beginning, peak,
and end of the contraction, respectively.
Rarely descend more than 30-40bpm below
baseline rate ,typically 10-20bpm.
Indicator of uteroplacental insufficiency
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45. Decelerations continued
VARIABLE DECELERATIONS
Decrease in the FHR is abrupt (onset to nadir
<30 sec) and ≥15 beats/min below the
baseline and lasting ≥15 sec but less than 2
min.
Not worrisome if isolated
◦ Causes
◦ Umblical Cord Compression
◦ Oligohydraminos
◦ Nuchal cord/cord stretching
PROLONGED DECELERATION
Deceleration is ≥15 beats/min below baseline
and lasts ≥2 min or more but <10 min.
Deceleration ≥10 min is a baseline change.
Caused by prolonged umbilical cord
compression (Hyperstimulation or Umblical
cord prolapse)
Other FHR patterns often seen
◦ Tachycardia
◦ Decreased variability
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46. RFHR vs NRFHR
REASSURING
◦ Normal baseline rate
◦ Moderate FHR variability
◦ Absence of late deceleration
◦ Presence of Acceleration(Not required)
NON-REASSURING
◦ Tachycardia
◦ Bradycardia
◦ Minimal or absent FHR variability
◦ Late decelerations
◦ Repetitive variable decelerations
◦ Absence of accelerations
Non hypoxia- anencephaly, drugs -opiates,
atropine, sepsis, defective cardiac conduction,
fetal sleep
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47. Management of NRFHR
•General measures to improve uterine blood flow and fetal oxygenation
◦ Lateral recumbent position
◦ Maternal oxygen administration
◦ Intravenous Hydration
◦ Discontinuation of Oxytocin
•Amnioinfusion
•Expedite delivery (C/S or Assisted vaginal delivery)
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48. Electronic Fetal Monitoring Versus
Intermittent Auscultation
• IA and EFM can perform similarly with respect to perinatal morbidity and mortality.
• The safety of managing an abnormal FHR pattern with IA alone has not been established.
• “ From the available evidence, the partograph is associated with improved perinatal outcomes
and is recommended for use with intermittent auscultation for intrapartum monitoring in low
resource settings”
- Housseine et.al
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49. References
• Williams obstetrics 24th edition
• Gabbe Obstetrics normal and problem pregnancies 7th edition
• Housseine N, Punt MC, Browne JL, Meguid T, Klipstein-Grobusch K, Kwast BE, et al. (2018) Strategies
for intrapartum foetal surveillance in low- and middle-income countries: A systematic review. PLoS
ONE 13(10): e0206295.
• Kamala BA, Ersdal HL, Dalen I, Abeid MS, Ngarina MM, Perlman JM, et al. (2018) Implementation of a
novel continuous fetal Doppler (Moyo) improves quality of intrapartum fetal heart rate monitoring in
a resource-limited tertiary hospital in Tanzania: An observational study. PLoS ONE 13(10): e0205698
• Fisseha et al. Quality of intrapartum and newborn care in Tigray, Northern Ethiopia BMC Pregnancy
and Childbirth (2019) 19:37
• Up-to-date 2018
• Lecturio.org
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Triple risk model in which an interplay of maternal factors,
fetal/placental factors, and a stressor contribute to fetal death.
Whereas these factors in isolation may be insufficient to cause
fetal death, they may prove lethal in combination. (From Warland J,
Mitchell EA. A triple risk model for unexplained late stillbirth. BMC
Pregnancy Childbirth. 2014;14:142.)
antepartum fetal assessment can have a significant impact on the
frequency and causes of antenatal fetal deaths.1 However,
A variety of “normal” and
“abnormal” FMC results or thresholds have been proposed, to
which the patient should be instructed to respond by presenting
for further evaluation of the condition of the fetus (Fig. 11-8).
These potential triggers for further evaluation include fewer than
three movements in 1 hour or no movements for 12 hours,
Sadovsky’s “movement alarm signal”; fewer than three movements
an hour for 2 consecutive days; or inability to count 10
movements in a 12-hour period, the Cardiff “count-to-10”
method advocated by Pearson and Weaver. The count-to-10
method has received wide scrutiny and is used perhaps most
frequently in clinical practice.
- Any threshold should be taken as a rule-of-thumb.
To perform the CST, the patient is placed in the semi-Fowler
position at a 30- to 45-degree angle with a slight left tilt to avoid
the supine hypotensive syndrome. Continuous external fetal
heart rate and uterine contraction monitoring is recorded, and
a baseline is obtained before stimulating uterine activity. Maternal
blood pressure is determined every 5 to 10 minutes to detect
maternal hypotension. In some cases, adequate uterine activity
occurs spontaneously, and additional uterine stimulation is
unnecessary. An adequate CST requires uterine contractions
of moderate intensity that last about 40 to 60 seconds with
a frequency of three in 10 minutes. These criteria were selected
to approximate the stress experienced by the fetus during the
first stage of labor. If uterine activity is absent or inadequate,
intravenous oxytocin is begun to initiate contractions, and it
is increased until adequate uterine contractions have been
achieved.32
the incidence of perinatal
death within 1 week of a negative CST (i.e., the false-negative
rate) to be less than 1 per 1000. (i.e., the false-negative
rate) to be less than 1 per 1000.2,42,63,64 Many of these deaths,
however, can be attributed to cord accidents, malformations,
placental abruption, and acute deterioration of glucose control
in patients with diabetes.
------If a trial of labor is to be undertaken
after a positive CST, the cervix should be favorable for induction
so that direct fetal heart rate monitoring and careful assessment
of uterine contractility with an intrauterine pressure catheter can
be performed. A suspicious or equivocal CST or one that is
unsatisfactory or shows hyperstimulation should be repeated in
24 hours.
Fetal heart rate accelerations may be absent during
periods of quiet fetal sleep.
However,
the fetus may fail to exhibit heart rate accelerations for up to 80
minutes and still be normal.
----Although an absence of fetal heart rate accelerations is most
often attributable to a quiet fetal sleep state, CNS depressants
such as narcotics and phenobarbital, as well as the β-blocker
propranolol, can reduce heart rate reactivity. Chronic smoking
is known to decrease fetal oxygenation through an increase in
fetal carboxyhemoglobin and a decrease in uterine blood flow.
Fetal heart rate accelerations are also decreased in smokers.
50% with sinusoidal pattern died.
--Bradycardia has a
higher positive predictive value for fetal compromise (fetal death
or fetal intolerance of labor) than does the nonreactive NST.
The fetal heart rate baseline evaluation must also take gestational
age into account, as with fetal heart rate reactivity. Vagal activity
has a greater influence on fetal heart rate at baseline as gestation
advances; thus baseline fetal heart rate will decrease from an
average of 155 beats/min at 20 weeks to 145 beats/min at 30
weeks.
--A low score on the
BPP does not prohibit attempted vaginal delivery if other obstetric
factors are favorable.
A low score on the
BPP does not prohibit attempted vaginal delivery if other obstetric
factors are favorable.
With Doppler ultrasound, we can obtain information about
uteroplacental blood flow and resistance, which may be markers
of fetal adaptation and reserve
For most of the conditions identified as constituting an increased
risk for fetal death, insufficient studies exist to permit an
evidence-based recommendation for a particular testing scheme.
