경북의대 성원준

Interpretation and management of

intrapartum fetal heart rate monitoring

External & Internal FHR monitoring

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Why is FHR monitoring important?

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BP

O2

HR

Efficacy of EFM

*EFM vs intermittent auscultation

• Cesarean section rate ↑ (RR:1.66, CI:1.30-2.13)

• Operative vaginal delivery ↑ (RR:1.16, CI:1.01-1.32)

• Neonatal seizure ↓ (RR:0.50, CI:0.31-0.80)

• Perinatal mortality ≒ (RR:0.85, CI:0.59-1.23)

• Cerebral palsy ≒ (RR:1.74, CI:0.97-3.11)

• PPV of nonreassuring pattern to predict CP: only 0.14%

-ACOG practice bulletin 106, 2009

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Interobserver and intraobserver variability

Comparisons of guidelines

• ACOG NICHD practice bulletin106, 2009

• FIGO updated consensus guideline, 2015

• RCOG NICE guideline CG190, 2017

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Paper speed

• Most countries: 1cm/min

• Netherlands: 2cm/min

• North America and Japan: 3cm/min

• At 3cm/min, variability appears reduced to a clinician familiar with 1cm/min scale

1min

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Baseline• Mean FHR rounded to increments of 5bpm during 10min

(>2min, no periodic or episodic change or marked variability) -ACOG 2009

• Mean level of most horizontal and less oscillatory for 10min -FIGO 2015

ACOG 2009,FIGO 2015

RCOG 2017

Normal 110-160 Reassuring 110-160

Tachycardia >160 Nonreassuring 100-109, 161-180

Bradycardia <110 Abnormal <100, >180

Baseline change

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Tachycardia

• Preterm fetus

• Maternal pyrexia

• Intrauterine infection

• Epidural analgesia

• Initial stage of nonacute fetal hypoxemia

• Beta-agonist, parasympathetic blockers

• Fetal supraventricular tachycardia, atrial flutter -ACOG 2009

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Bradycardia

• Postdate fetus (usually 100-110)

• Maternal hypothermia

• Beta-blockers

• Fetal AV block -ACOG 2009

• 100-110 of normal variability and no variable, late decelerations: Continue usual care -RCOG 2017

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Variability• Fluctuations in baseline FHR, quantified as amplitude of peak to trough

– ACOG 2009

• Oscilliation in FHR, average bandwidth amplitude in 1min segments

– FIGO 2015

ACOG 2009 FIGO 2015 RCOG 2017

Absent undetect

Minimal ≤5 Reduced <5 for 50min Reassuring 5-25

Moderate (normal)

6-25 Normal 5-25 Nonreassuring <5 for 30-50min>25 for 15-25min

Marked >25 Increased(Saltatory)

>25 for 30min Abnormal <5 for 50min>25 for 25min

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Variability

Moderate : 6-25 bpm

Marked : > 25 bpm

Minimal : ≤ 5bpm

Absent : undetectable

-ACOG 200911/42

Reduced variability

• Ongoing CNS hypoxia/acidosis

• Previous cerebral injury

• Infection

• Parasympathetic blockers

• Deep sleep: lower range of normality

• Following initially normal CTG, reduced variability due to hypoxia is

very unlikely to occur during labor without decelerations and rise in

baseline -FIGO 2015

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Increased variability

• Unknown pathophysiology

• Recurrent decelerations? with very acute hypoxia/acidosis

• Fetal autonomic instability -FIGO 2015

Not always benign

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Accelerations

• Abrupt (<30sec onset to peak)

≥32weeks, ≥15bpm for ≥15sec

<32weeks, ≥10bpm for ≥10sec

-ACOG 2009

• Neurologically responsive fetus without hypoxia/acidosis

• Absence of accelerations in normal CTG is unlikely to indicate hypoxia/acidosis -FIGO 2015

• Presence of accelerations with reduced variability is a sign that the baby is healthy -RCOG 2017

>15

>15

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Decelerations

• Early

• Variable

• Late

• Prolonged

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Early decelerations

• Symmetrical gradual decrease

(onset to nadir ≥30sec)

coincident with contraction

-ACOG 2009

• Shallow

• Benign

• Fetal head compression

-FIGO 2015

>30

shallow

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Variable decelerations

• Abrupt decrease

(onset to nadir<30sec)

≥15bpm for ≥15sec (<2min)

• Onset, depth and duration vary

with contractions

• Umbilical cord compression

-ACOG 2009

• Baroreceptor mediated response

to increased arterial pressure

-FIGO 2015

<30s

≥15b

≥15s, <2min

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• Concerning characteristics of variable decelerations -RCOG 2017

- >60sec

- reduced variability within deceleration

- failure to return to baseline

- biphase (W) shape

- no shouldering

& U shape by FIGO 2015

• Intermittent vs recurrent variable decelerations -ACOG 2009

if, ≥50% of contractions: impending fetal acidemia

Variable decelerationsa

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Late decelerations

• Symmetrical gradual decrease

(onset to nadir ≥30sec)

• Delayed in timing, nadir after

peak of contraction -ACOG 2009

• Starts >20sec after onset of

contraction -FIGO 2015

• Uteroplacental insufficiency

• Chemoreceptor mediated

response to fetal hypoxemia

-FIGO 2015

≥30s

≥15b

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Prolonged decelerations

• FHR decrease of ≥15bpm for ≥2min & <10min –ACOG 2009

• FHR decrease >3min –FIGO 2015, –RCOG 2017

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Prolonged decelerations

• Maternal hypotension (postepidural)• Umbilical cord prolapse or occlusion• Rapid fetal descent• Tachysystole• Placental abruption• Uterine rupture -ACOG 2009, RCOG 2017

• Hypoxemia and chemoreceptor mediated• >5min, <80bpm and reduced variability within deceleration

: acute hypoxia/acidosis- emergent intervention -FIGO 2015

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Sinusoidal pattern• Regular, smooth, undulating signal with amplitude of 5-15bpm,

3-5cycles/min, without acceleration, >30min -FIGO 2015

• Apparent smooth, undulation pattern, 3-5cycles/min, ≥20min

-ACOG 2009

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Sinusoidal pattern

• Fetal anemia

• Acute fetal hypoxia

• Infection

• Cardiac malformation

• Hydrocephalus

• Gastroschisis -FIGO 2015

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Uterine tone

• Only frequency of contractions can be reliable

• Intensity and duration also contribute to FHR -FIGO 2015

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Tachysystole

• >5 contractions in 10min (averaged over 30min)

–ACOG 2009

• >5 contractions in 10min (two successive periods or averaged over 30min)

–FIGO 2015

• Hyperstimulation or hypercontractility

: abandoned terms –ACOG 2009

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Normal fetal acid-base status? No CP!

• Accelerations: fetus is not acidemic

• Variability: no consensus (fetus is not academic usually)

study 1. Moderate variability: cord pH>7.15

2. Variable or late decelerations with normal variability

: cord pH>7.0 in 97%

3. Most cases of adverse neonatal outcomes

: normal variability -ACOG 2009

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Interpretation of EFM

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3 tier systemACOG Category I Category II Category III

FIGO Normal Suspicious Pathological

RCOG Normal Suspicious Pathological

1 nonreassuring 2 nonreassuring or1 abnormal pattern

All reassuring

ACOG practice bulletin 106, 2009

Category I Category II Category III

All of the following:

Baseline FHR: 110-160 Variability: moderate

Late or variable decel: -

Early decel: +/-Accel: +/-

Examples:

Bradycardia with no absent variabilityTachycardia

Minimal variabilityAbsent variability with no recurrent

decelerationsMarked variability

Absence of induced accelerations after stimulation

Recurrent variable decelerations with minimal or moderate variabilityRecurrent late decelerations with

moderate variabilityProlonged decelerations (2-10min)Variable decelerations with other

characteristics (slow return, overshoots, shoulders)

Either:

Absent variability with-Recurrent late decel

-Recurrent variable decel-Bradycardia

Sinusoidal pattern

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FIGO classification 2015aa

Normal Suspicous Pathological

Baseline 110-160 bpm

Lacking at least one of normality, but no pathological features

<100 bpm

Variability 5-25 bpm<5bpm, >50min>25bpm, >30minSinusoidal pattern

Decelerations No repetitive (<50%)

Repetitive (>50%) late decel >30min,Single prolonged

deceleration >5min

Interpretation No hypoxia/acidosis Low probability High probability

Management No intervention Action to correct Expedite delivery

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Reassuring Nonreassuring Abnormal

Baseline 110-160 100-109 or 161-180 <100 or >180

Variability 5-25<5 (30-50min)>25 (15-25min)

<5 (>50min)>25 (>25min)

Sinusoidal

DecelerationsNone or early,

Variable decel with no concern <90min

All others

Recurrent variabledecel with

concern >30min,Late decel >30min,

Bradycardia,Prolonged decel

RCOG guidelines CG 190

Concerning characteristics of variable decelerations:

>60sec, reduce variability within decelerations, failure to return to baseline, W shape, no shouldering

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RCOG guidelines CG 190aa

Category Definition Management

Normal All features reassuring Continue CTG

Suspicious 1 nonreassuring

Correct underlying causeFull set of observationsInform an obstetrician or a senior midwifeDocument a plan for reviewingTake her preferences into account

Pathological2 nonreassuring or1 abnormal

Review by an obstetrician and a senior midwifeExclude acute event and correct underlying causeOffer digital scalp stimulationConsider fetal blood samplingConsider expediting birthTake the woman’s preferences into account

Urgent intervention

bradycardia, or prolonged decel

All the aboves, prepare for urgent birthExpedite the birth if bradycardia >9min

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Management of EFM

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Management of ACOG

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Intervention effect should be apparent within 30 minutes of application

Intrauterine resuscitation

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Clarks et al, AJOG 2013Timmins et al, OGCNA 2015

How to approach category II, Clarks et al.

Significant decel: Variable decel over

60sec, <60bpm: Any late decel

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Management of intrapartum FHR tracing

ManagementIntrauterine

resuscitation & Delivery

InterpretationACOG Category IIIFIGO PathologicalRCOG Pathological

30min

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Management of intrapartum FHR tracing

ManagementACOG IUR & Surveillance

FIGO RCOG IUR & DeliveryClarks et al. Consider delivery if abnormal

progress or remote from delivery

InterpretationACOG Category IIFIGO PathologicalRCOG Pathological

IUR: Intra Uterine Resuscitation

60min

Management of intrapartum FHR tracing

InterpretationACOG Category IIFIGO Suspicious

RCOG Pathological

ManagementACOG FIGO IUR & Surveillance

RCOG IUR & DeliveryClarks et al. Consider delivery if abnormal

progress or remote from delivery

IUR: Intra Uterine Resuscitation

60min

Over 50 min

Management of intrapartum FHR tracing

InterpretationACOG Category IIFIGO PathologicalRCOG Pathological

ManagementACOG FIGO RCOG IUR & Delivery

Clarks et al. Observe 1 hr & Delivery

IUR: Intra Uterine Resuscitation

Interobserver and intraobserver variability

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Take home messages

• FHR monitor: medical device without instruction manual

• Interobserver and intraobserver variability

• Efforts for standardization

• Consider labor progress before making actions

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