When is a biophysical exam (BPP) recommended during pregnancy?

Biophysical Profile (BPP) Recommendations During Pregnancy

Biophysical profile testing is recommended for pregnancies at high risk for adverse fetal outcomes but is not recommended for routine use in low-risk pregnancies. 1

Indications for BPP Testing

• BPP is indicated in high-risk pregnancies with conditions associated with increased risk of stillbirth 1
• Common indications include:
  • Intrauterine growth restriction (IUGR) 1
  • Maternal hypertensive disorders 1
  • Diabetes mellitus 1
  • Post-term pregnancy 1
  • Decreased fetal movement 1
  • Previous stillbirth 1
  • Multiple gestation with complications 1
  • Oligohydramnios or polyhydramnios 1

Timing of BPP Initiation

• For most high-risk conditions, BPP is typically initiated at 32-34 weeks' gestation 1
• Timing should be individualized based on:
  • Specific risk factors present 1
  • Gestational age 1
  • Likelihood of neonatal survival with intervention 1
• Earlier initiation may be warranted in cases of severe early-onset IUGR or other significant high-risk conditions 1

Frequency of Testing

• Standard practice is weekly or twice-weekly testing in high-risk pregnancies 1
• For IUGR without absent/reversed end-diastolic flow, weekly testing is suggested 1
• More frequent testing (twice weekly) is recommended when:
  • IUGR is complicated by absent or reversed end-diastolic flow in umbilical artery 1
  • Other significant comorbidities are present 1
  • Previous abnormal test results require closer monitoring 1

BPP Components and Interpretation

• Standard BPP includes assessment of:
  • Fetal breathing movements (≥30 seconds within 30 minutes) 1
  • Gross body movements (≥3 discrete movements) 1
  • Fetal tone (≥1 episode of extension with return to flexion) 1
  • Amniotic fluid volume (≥1 pocket measuring 2 cm) 1
  • Non-stress test (optional component) 1
• Scoring:
  • Each component meeting criteria receives 2 points 1
  • Total score of 8-10 is normal 1
  • Score of 6 is equivocal 1
  • Score of 4 or less is abnormal 1

Modified BPP

• Modified BPP consists of non-stress test plus amniotic fluid assessment 1
• This is an acceptable alternative to full BPP with similar predictive value 1
• May be particularly useful in cases of IUGR or oligohydramnios 1
• Has similar negative predictive value to full BPP (>99%) 1

Management Based on BPP Results

• Normal BPP (score 8-10): Continue surveillance as scheduled 1
• Equivocal BPP (score 6): Consider delivery if term; repeat testing within 24 hours if preterm 1
• Abnormal BPP (score ≤4): Delivery is generally indicated regardless of gestational age 1
• At term with abnormal BPP: Delivery is recommended 1
• For abnormal BPP in preterm pregnancy: Management depends on gestational age, severity of findings, and other clinical factors 1

Important Caveats and Limitations

• BPP has high negative predictive value but limited positive predictive value 1, 2
• False positive results may lead to unnecessary interventions including preterm delivery 1
• BPP cannot predict stillbirth related to acute events such as placental abruption or cord accidents 1
• In FGR, abnormal BPP is a late manifestation that typically appears 48-72 hours after ductus venosus Doppler abnormalities 1
• Evidence from randomized controlled trials supporting BPP use is limited 2
• Some studies suggest BPP may increase cesarean section rates without clear improvement in outcomes 2

Alternative Testing Methods

• Simplified or rapid BPP (amniotic fluid index plus sound-provoked fetal movement) may be an effective screening tool with high sensitivity 3, 4
• Umbilical artery Doppler velocimetry is particularly valuable in IUGR secondary to uteroplacental insufficiency 1
• For early-onset severe IUGR, Doppler studies may provide better guidance than BPP alone 1