BIOPHYSICAL PROFILEFLAME LECTURE: 56

STELLER 7.2.14

Learning Objectives

To understand rationale for fetal assessment To describe approaches for assessment of fetal well being Prerequisite:

FLAME LECTURE 54: Outpatient Antenatal Testing See also – for closely related topics

FLAME LECTURE 53: Overview of Interpreting Fetal Heart Rate Tracings

FLAME LECTURE 54B: The Nonstress Test (NST) and Contraction Stress Test (CST)

FLAME LECTURE 57: Assessment of fetal movement FLAME LECTURE 59: Assessment of amniotic fluid volume

Rationale of Prenatal Outpatient Fetal Assessment

GoalsDetect uteroplacental insufficiencyPrevent stillbirthAvoid unnecessary iatrogenic preterm delivery

Physiologic basis -- The fetal brain is incredibly sensitive to changes in O2 and pH:Under stress, fetal movements decrease as the

fetus attempts to conserve energy1-2

Hypoxia/acidemia Neurologic depression1. Olesen AG. Acta Obstet Gynecol Scand. 20042. Manning FA. AJOG 1993

Antepartum Fetal Distress Cascade

HYPOXIA

ACIDOSIS

LATE DECELERATIONS APPEAR(CST)

ACCELERATIONS DISAPPEAR(NST)

BREATHING STOPS(BPP)

MOVEMENT CEASES(BPP, FMC)

FETAL TONE ABSENT(BPP)

3. Porto M. Clin Ob Gyn. 1987

FETAL CNS CONTROLTONE (7 weeks)

Cortical & subcortical areas

MOVEMENT (9weeks)Cortical Nuclei

BREATHING (20 weeks)Ventral surface 4th ventricle

REACTIVITY (26-28weeks)Posterior Hypothalamus

Looking at variables derived from CNS centers is ideal Tone

Body movements Breathing movements Cardiac activity Eye movements Swallowing Micturition

HYPOXIA

MATURITY

Biophysical Profile (BPP)

Combines the NST, AFI and assessments of fetal breathing, body and limb movements in an exam that lasts up to 30 minutes

BPP score is linearly correlated with fetal pH4

The risk of fetal death within one week of a normal BPP is estimated to be 1/13005

Is initiated ~24-32 weeks qweekly/biweekly False neg rate: .07-.08%, False pos rate: 40-50%6-

84. Manning FA. Am J Obstet Gynec 19935. Manning FA. Am J Obstet Gynec 19876. Mangesi L. Cochrane Database Syst Rev 20077. Freeman RK. Am J Obstet Gynecol 19828. Baschat AA. Ultrasound Obstet Gynecol. 2006

Rationale of Including Assessment of Amniotic Fluid Volume in the BPP In fetal hypoxia, fetal autoregulation of vascular tone

preserves essential organsBlood flow is directed to the brain, heart and adrenals

and away from the kidneys Over time: a decrease in renal perfusion a decrease in

fetal urine production oligohydramniosTherefore low AVF is a marker of CHRONIC uteroplacental

insufficiency The other, CNS-derived ultrasound markers previously

described are ACUTE indicators of fetal acidemia

Fetal Breathing Movements

Regular fetal breathing noted by 20-21 weeksMore frequent movement during REM sleepDownward movement of the diaphragm, inward chest

wall movementIncreased with hyperglycemiaDecreased with hypoxia, smoking, narcotics, labor

EXAMPLE VIDEO

Biophysical Profile – Scoring9-12

FIVE components Reactive NST Maximum vertical pocket >

2cm or AFI > 5 ≥ 1 episode of breathing lasting

≥ 30s ≥3 discrete body/limb

movements ≥ 1 episode of limb extension

with return to flexion, or opening/closing of hand

Each component is worth TWO points (no partial credit) Normal: ≥ 8/10 (or 8/8 without

NST) Equivocal: 6/10 Abnormal: ≤4/10

NST may be omitted without compromising test validity if the other 4 components = 8/8

9. Chamberlain PF AJOG 1984 10. Manning FA. AJOG 199011. Nabhan AF. Cochrane 200812. Manning FA. AJOG 1987

BPP Management

Score Interpretation Management

10 Low risk for asphyxia Repeat in 7 days, 3-4 days for diabetes or > 41 weeks

8 Low risk for asphyxia Same as above, consider delivery if oligohydramnios

6 Suspect asphyxia 36 wk/favorable Cx or oligo deliver; L/S<2 repeat < 24h

4 Strongly suspect asphyxia

>32 – 34 weeks DELIVER; < 32 wks consider extending or repeating

< 2 Probable asphyxia +/- Extend test time, if still < 4 DELIVER regardless of GA

IMPORTANT LINKS

PRACTICE BULLETIN 145 – Antepartum Fetal Surveillance

OTHER REFERENCES

1. Olesen AG. Acta Obstet Gynecol Scand. 2004

2. Manning FA. AJOG. 1993

3. Porto M. Clin Ob Gyn. 1987

4. Manning FA. Am J Obstet Gynec 1993

5. Manning FA. Am J Obstet Gynec 1987

6. Mangesi L. Cochrane Database Syst Rev 2007

7. Freeman RK. Am J Obstet Gynecol 1982

8. Baschat AA. Ultrasound Obstet Gynecol. 2006

9. Chamberlain PF AJOG 1984

10. Manning FA. AJOG 1990

11. Nabhan AF. Cochrane 2008

12. Manning FA. AJOG 1987