Fetal Monitoring Dr. Anjoo - PowerPoint Presentation

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Fetal Monitoring

Dr.

Anjoo

Agarwal

Professor

Dept of

Obs

&

gyn

KGMU, Lucknow

Slide2

Objectives

Understand aims of fetal monitoring

Understand methods of fetal monitoring

Understand limitations of fetal

monitoring

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Aims of Fetal Monitoring

Prevention of fetal death

Avoidance of unnecessary interventions

ACOG, AAP 2012

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23 yrs old woman G2P1+0 (1

st

FTND, A&H) presents at 38 wks pregnancy with C/o diminished fetal moments since 2 days.

Q. How significant do you think the problem is & what should be your next step?

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Significance

Diminished fetal activity, may be a harbinger of impending fetal death

Sadovsky

, 1973

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Low Risk vs High Risk

Any pregnancy may become high risk any time

C/o diminished fetal activity important in all cases

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Role of Gestation ?

Fetal activity starts at 7 wks

General body movements become

organised

20-30 wks

Fetal movement maturation continues till 36 wks

Criteria for interpretation of tests varies with gestation

Fetal viability an important consideration

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Methods of Assessment

Antepartum

:

DFMC

NST

CST

Biophysical Profile

Doppler

Velocimetry

Intrapartum

:

External or Indirect

Internal or Direct

Fetal scalp blood sampling

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DFMC

Cardiff “Count to 10”

One hour after each meal

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NST

FHR Acceleration in response to fetal movements

Test of fetal condition

Normal – reactive

Abnormal – non reactive

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Reactive NST

≥ 32 weeks – 2 accelerations ≥ 15

bpm

≥ 15 sec during 20 min

< 32 wks – 2 accelerations ≥ 10

bpm

≥ 10 sec during 20 min

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Fetal Heart Rate Acceleration

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Electronic Fetal Monitoring

Pattern

Definition

Baseline

The mean FHR rounded to increments

of 5

bpm

during a 10 min segment, excluding

Periodic & episodic changes

Segment of baseline that differ by more than 25

bpm

The baseline must be for a minimum 2 min in any 10 min segment or the baseline for that time period is indeterminate. In this case, one may refer to the prior 10 min window to determine of baseline

Normal FHR baseline: 110 – 160

bpm

Tachycardia: FHR baseline > 160

bpm

Bradycardia

: FHR baseline < 110

bpm

Fluctuations in the baseline FHR that are irregular in amplitude & frequency

Baseline Variability

Variability is visually quantified as the amplitude of peak-to-trough in

bpm

Absent – amplitude range undetectable

Minimal – amplitude range detectable

but ≤ 5

bpm

or fewer

Moderate – amplitude range 6-25

bpm

Marked – amplitude range > 25

bpm

Acceleration

A visually apparent abrupt increase (onset to peak in

< 30 sec) in the FHR

At 32 wks & beyond, an acceleration has a peak of 15

bpm

or more have baseline, with a duration or more but less than 2 min from onset to return

Before 32 wks, an acceleration has a peak of 10

bpm

or more above baseline, with a duration of ≥ 10 sec < 2 min from onset to return

Prolonged acceleration lasts ≥ 2 min but < 10 min

If an acceleration last 10 min, it is a baseline change

Visually apparent usually symmetrical gradual decrease & return of the FHR associated with a uterine contraction

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No Variability

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Minimal Variability

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Moderate Variability

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Increased Variability

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Saltatory Pattern

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CST/OCT

Tests

uteroplacental

function contraction stimulated by

oxytocin

infusion

Late decelerations indicate positive test

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Biophysical Profile

Nonstress

test

Fetal breathing

Fetal movement

Fetal tone

Amniotic

fluid volume

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Modified Biophysical Profile

NST + AFI (cut off 5 cm)

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Doppler Velocimetry

Umbilical artery

MCA

Ductus

Venosus

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Umbilical Artery Doppler

Abnormal if –

S/D > 95% percentile for GA

Absent end diastolic flow – 10% PM

Reversed end diastolic flow – 33% PM

Utility only in FGR

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MCA

Fetal Hypoxia → brain sparing → ↑

Cerebro

vascular resistance (RI)

Also useful in fetal

anaemia

where ↑ PSV

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Ductus Venosus

Good correlation with

perinatal

outcome

But by the time affected it is too late

Still in experimental stage

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Final Recommendations

Start at 32-34 weeks in HR cases

Severe complications may require testing at 26-28 weeks

Repeat weekly/ every 7 days

Most commonly used – modified biophysical profile

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MCQ

NST is used to test

1

uteroplacental

bloodflow

2 fetal condition

3 response to uterine contractions

4 fetal

anaemia

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MCQ

A 35 yr old G1 P0+0 presents at 34 wks with GDM. It is recommended that she be monitored by

1 weekly NST

2 DFMC

3 Daily

doppler

4 all of the above

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MCQ

The acceleration of FHR in NST should be of

1 at least 20 min duration

2 at least 20 sec duration

3 at least 15 sec duration

4 at least 15 min duration