Antenatal Fetal Monitoring

Antepartum Fetal Surveillance

The primary goal - avoidance of intrauterine fetal death

Cornerstone of this assessment is to prevent fetal hypoxemia and acidemia

routine prenatal care populations with an increased risk of fetal

demise

Fetal Assessment

HIGH-RISKPREGNANCIES

1. FETAL• Anatomic anomaly• Decreased fetal movement• Heart block• Intraamniotic infection• Intrauterine growth restriction• Multiple gestation• Oligohydramnios

2. MATERNAL-FETAL

• Abruptio placenta• Abnormal serum screening (low PAPP-A, high M

SAFP)• Placenta previa, vasa previa• Postterm or postdates,premature rupture of fetal

membranes• Threatened preterm delivery

3. MATERNAL

• Advanced maternal age• Cardiac disease (severe)• GDM• Hypertension, chronic• Hypertension, gestational• Substance abuse• Systemic lupus erythematosis• Thyroid disease• Thrombophilia or thromboembolic disease

ASSESSMENTS FOR LOW-RISK PREGNANCIES• USG: Dating scan 1st trimester-Done as early as possible determination of fetal number fetal viability fetal position gestational age placental location amniotic fluid volume presence or absence of a maternal pelvic mass presence of gross fetal malformations

2nd Trimester USG

– Fetal anatomic screening

– specifically at 18 to 20 weeks’ gestation, when visualization of the anatomic features is adequate.

– identify sonographic markers of fetal aneuploidy

• SONOGRAPHIC GUIDANCE – for an invasive procedure as amniocentesis

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FETAL MOVEMENT COUNTING

• Quickening 16-22 wks• Fetal hypoxemia is typically associated wit

h a reduction in fetal activity• Usually after a meal when the fetus is mor

e active, if 10 movements are not detected in 1 hour, further testing is often recommended

• Costeffective first line screening test

FETAL ASSESSMENT IN HIGH-RISKPREGNANCIES

1. CARDIOTOCOGRAPHY2. NONSTRESS TEST3. CONTRACTION STRESS TEST4. ULTRASOUND5. GROWTH ASSESSMENT6. AMNIOTIC FLUID ASSESSMENT7. BIOPHYSICAL PROFILE8. DOPPLER

CARDIOTOCOGRAPHY

• Principle: fetal neurologic system, through its afferent and efferent networks, serves as a key mediator to demonstrate fetal well-being

• 3 basic elements

Term Characteristic

Description

Baseline Definition Mean fetal heart rate, rounded to increments of 5 beats/min (e.g. 140, 145);

Bradycardia <110 beats per minute

Tachycardia >160 beats per minute

Term Characteristic

Description

Variability Definition Fluctuations of the baseline heart rate;

Absent Undetectable

Minimal Undetectable to ≤5 beats/min

Moderate 6-25 beats/min

Marked >25 beats/min

Term Characteristic

Description

Acceleration Definition Abrupt increase ≥15 beats/min lasting ≥15 s

Prolonged ≥2 min and <10 min (≥10 min is a baseline change)

Term Characteristic

Description

Deceleration Definition Decreases in the fetal heart rate

Early Gradual decrease onset to nadir ≥30 s with contraction

Late Gradual decrease onset to nadir ≥30 s; nadir of deceleration occurring after peak of contraction

NST

• A normal NST : def: REACTIVE NST A 20-minute fetal heart rate tracing that contains

two heart rate accelerations lasting 15 seconds or longer that peak 15 beats or more above the baseline

• If abnormal extended upto 20-40 min• A nonreactive NST or an NST with specific abnormalit

ies (e.g., high or low baseline, decelerations) should be followed by a BPP

CONTRACTION STRESS TEST

• CST assesses the fetal heart rate response in the presence of contractions

• improves on the specificity and sensitivity of the NST by assessing the fetal response to stress.

ULTRASOUND

• Fetal echocardiography at 20 to 22 weeks’ gestation in all pregnancies at high-risk of a fetal cardiac malformation

• Dm,• drug,• cardiac lesion,• in vitro fertilisartion

3D ULTRASOUND• Surface rendering mode – craniofacial anomalies, intracranial lesion

s, spinal anomalies,ventral wall defects, and fetal tumors

• In early pregnancy: • more accurate measurements of the gestational sac, yolk sac, and crow

n-rump length• more accurate midsagittal view of the fetus for measuring nuchal transluc

ency.

• To measure tissue volume:• cervical insufficiency.

• measurement of placental volume in the first trimester may predict fetuses at risk of intrauterine growth restriction

GROWTH ASSESSMENT

• Four separate leopold maneuvers• Uterus can be palpated above the pelvic brim at approximately 12 w

eeks’ gestation. • Thereafter, fundal height should increase by approximately 1 cm per

week, reaching the level of the umbilicus at 20 to 22 weeks’ gestation.

• Between 20 and 32 weeks’ gestation, the fundal height (in centimeters, from the superior edge of the pubic symphysis) is approximately equal to the gestational age (in weeks)

• BPD gest age assessment in 2nd & 3rd trimester

AMNIOTIC FLUID ASSESSMENT

• AFI • semiquantitative method• <5 / >20

• Maximum vertical pocket• semiquantitative method• <2 / >10

Element Criterion

Breathing ≥1 episode of breathing movements lasting 30seconds

Movement ≥3 discrete body or limb movements

Tone ≥1 episode of active extension and flexion oflimbs or trunk

Amniotic fluid ≥1 pocket of amniotic fluid measuring ≥2 cm intwo perpendicular planes

Nonstress test ≥2 fetal heart rate accelerations lasting ≥15 secondsover 20 minutes

• Fetal tone appears at 7.5 to 8.5 weeks,• Fetal movement at 9 weeks,• Fetal breathing at 20 to 22 weeks,• FHR reactivity at 24 to 28 weeks’ gestation

Order of appearance

• Decreased diastolic flow suggests increased placental vascular resistance and fetal compromise.

• Severely abnormal umbilical artery doppler velocimetry (defined as absent or reversed diastolic flow) is an especially ominous observation and is associated with poor perinatal outcome,

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Antenatal Fetal Monitoring

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