Antepartum Fetal Surveillance

‘HELLO BABY, HOW ARE YOU?’

Presented By: Janet L. Smith, RNC, BSN

Author: Ruth Saathoff, RNC, BSN

OBJECTIVES:At the end of this class the learner will be able to:

Name 5 methods of monitoring the fetus for well-being

Describe the physiology of maternal and fetal circulation in the relationship to fetal reserve.

Identify the maternal and fetal conditions that indicate a need for fetal surveillance.

Indications for Fetal EvaluationMaternal risk factors

Pre-existing maternal disease Exposure to teratogens in 1st trimester Substance abuse Infertility or conception within 3 months of last

delivery(cont.)

Indications for Fetal Evaluation

Maternal Factors (cont) History of OB complication

• Oligohydramnios, Gestational Hypertension, etc. Previous pregnancy loss PROM > 24 hours Familial history of genetic abnormality Post dates

Indications for Fetal Evaluation

Fetal risk factors Prematurity SGA or LGA Intrauterine growth restriction (IUGR) Known anomaly History of IUFD Fetal cardiac arrhythmias Decreased fetal movement

Why and When

Why do we think of a well baby in terms of placental perfusion?

Oxygen & nutrients are needed for fetus Risk factors may reduce delivery to fetus Good oxygen & nutrient delivery results in movement

and growthWhen is surveillance started?

When risk is present IDDM (type 1) - 32 weeks Previous loss - 34 weeks

Fetal Movement Counts

FM indicator of intact Central Nervous System function

First line defense to identify the fetus in trouble

30-50% of IUFD occur in women with no identifiable risk factors

FAD

Methods for Fetal Movement Counts

Count-to-ten

Counting after meals

Evening monitoring

Interpretation

Report when criteria not metReport no movement over 8 hoursReport sudden violent increase in fetal

activity followed by cessation of movement

Report changes in normal pattern of fetal movement

Non-stress Test (NST)

Fetal movement typically accompanied by FHR accels when CNS intact and with adequate oxygenation

Procedure: Position sitting, semi-Fowler’s with tilt to

either side Good quality EFM tracing for 20-40 min May monitor up to 60 min

Interpretation

What to look at (5 parameters) What’s the baseline? Is there variability present? Any uterine activity present? Any accels present? Any decels present?

Assessment

Baseline Variability Accelerations Decelerations

Uterine Activity Fetal Movement

Interpretation

Reactive: 2 accels in 20 min. 15 bpm X 15 sec. 15 sec. from start of accel to end of accel 15 bpm at apex of accel gestation < 32 weeks

• 10 bpm X 10 sec.• frequent decels of 10-20 sec.

Interpretation

Nonreactive: does not meet above criteria if not reactive in 60 min. unlikely to become

so; call HCP isolated decels seen in as many as 33%

Example at term

Example 31 weeks

Retesting

If no risk factors, unlikely to have FD in one week

With risk factors, repeat 2 times a week

If pregnancy status changes, repeat in 24-48 hours

Assessment

NST: Non-reactive after 40 minPossible causes:

fetal sleep smoking before coming Maternal medications immature CNS fetal hypoxia

Well, now what? My NST is Non-ReactiveJuice mythDo Fetal Acoustic Stimulation Test

(FAST) Usually elicited after 28 weeks Can be done after 10 min of non-reactive

pattern Handheld device generates a low frequency

(82 decibels) vibro-acoustic stimulus Apply for 3-5 sec avoiding fetal head; may

repeat X 2 at least 1 min apart May cause some level of stress

Results of FASTCauses ‘Moro’ or startle reflex if CNS

intactIncrease in FHR

1 accel of 15 bpm over 2 minutes 2 accels of 15 bpm for at least 15 sec within

5 minutes of testUseful way to reduce number of non-

reactive NST'sShortens testing time

Vibroacoustic Stimulation

Well, now what...My NST is Non-Reactive?

Options: Contraction Stress Test (CST)

• assumes uteroplacental insufficiency will show hypoxia with late decels with contractions

Biophysical Profile (BPP)• Ultrasound assessment of acute and chronic

markers show good predictor of fetal well-being

CSTModes

Nipple stimulation (BST)• may be poorly received by patient• noninvasive

IV oxytocin (OCT)• requires invasive procedure

Spontaneous contractions

Interpretation

FHR response to stress of contractions 3 contractions lasting 40-60 sec. in 10 min.

‘Negative’ is absence of late decels (That’s good!) ‘Positive’ is presence of late decels (That’s bad!)

> 50% of contractions--need to deliver

‘Equivocal’ is presence of some lates <50% of contractions

Tachysystole or Unsatisfactory Results Considered testing failure and are not clinically useful

‘Suspicious’ Variable Decelerations

Negative

Positive – Late Decelerations

Suspicious – Variable Decelerations

Test Failure - UterineTachysystole

BPPParameters

Fetal Tone (FT) (7-8wks)

Fetal Movement (FM) (9wks)

Fetal Breathing Movements (FBM)) (20-21wks)

Amniotic Fluid Index (AFI) > 6 cms NST (Accelerations 30-32 wks)

Need high tech equipment/skilled technician

Non-invasive, highly predictive

ScoringBiophysicalVariable

Normal(Score = 2)

Abnormal(Score = 0)

Fetal breathing movements

1 or more episodes of ≥ 20 s within 30 min Absent or no episode of ≥ 20 s within 30 min

Gross body movements 2 or more discrete body/ limb movements within 30 min (episodes of active continuous movement considered as a single movement)

<2 episodes of body/limb movements within 30 min

Fetal tone 1 or more episodes of active extension with return to flexion of fetal limb(s) or trunk (opening and closing of hand considered normal tone)

Slow extension with return to partial flexion, movement of limb in full extension, absent fetal movement, or partially open fetal hand

Reactive FHR 2 or more episodes of acceleration of ≥ 15 bmp* and of >15 s associated with fetal movement within 20 min

1 or more episodes of acceleration of fetal heart rate or acceleration of <15 bmp within 20 min

Qualitative AFV 1 or more pockets of fluid measuring ≥ 2 cm in vertical axis

Either no pockets or largest pocket <2 cm in vertical axis

Interpretation

Scoring 10 point scale (if performed with a NST) 8-10 indicates fetus in good condition 6 indicates need to repeat in 4-6 hours <6 indicates need for delivery AFI < 6 cms indicates delivery

Other Surveillances

Amniocentesis Fetal lung maturity Testing- genetic, cultures, change in

optical density

Ultrasound Examination Uterine contents Fetal biometry / dating Fetal anatomic examination

Other Surveillance Options

Doppler Flow Studies Checks BP of uterine and placental vessels Associated with fetal growth deficiency

References:American Academy of Pediatrics, American College of Obstetricians &

Gynecologists, Guidelines for Perinatal Care (5th ed. 2002), Antepartum surveillance, pp. 89-107.

AWHONN Fetal Heart Rate Monitoring Principles and Practices 4th Ed.

Christensen FC, Olson K, Rayburn WF (2003). Cross-over trial comparing maternal acceptance of two fetal movement charts. Journal of Maternal-Fetal and Neonatal Medicine, 14(2), pp. 118-122.

Devoe, L, Glob. libr. women's med.,(ISSN: 1756-2228) 2008; DOI 10.3843/GLOWM.10210

Martin, E.J., Intrapartum Management Modules (3rd ed. 2002), Performing fetal surveillance testing, pp. 411-413.

Mattson, S., Smith, J.E., Core Curriculum for Maternal-Newborn Nursing (3rd. ed.,2004), Clinical practice pp. 165-166.

Simpson, K. R., Creehan, P.A., Perinatal Nursing (2nd ed., 2001), Fetal surveillance, pp. 147-154.