How often should a Biophysical Profile (BPP) be repeated?

When to Repeat a Biophysical Profile (BPP)

For fetuses at risk of demise, BPP testing should be performed at least weekly, with twice-weekly or even daily testing for those at highest risk, from the point of viability until delivery. 1

Standard Frequency Based on Risk Level

High-Risk Pregnancies (FGR, Hypertension, Diabetes, Post-dates)

• Weekly BPP testing is the baseline standard for pregnancies at increased risk for adverse fetal outcomes after viability 1
• Twice-weekly testing is indicated for fetuses at highest risk for fetal demise 1
• Daily or more frequent testing may be necessary in critical situations where fetal compromise is suspected 1

Specific Scenarios Requiring Increased Frequency

Fetal Growth Restriction (FGR):

• Weekly testing for FGR without absent/reversed end-diastolic velocity (AEDV/REDV) in umbilical artery 1, 2
• Increase to twice-weekly or more when FGR is complicated by AEDV/REDV or other comorbidities 1, 2
• Daily testing (1-2 times per day) when reversed end-diastolic velocity is present 2, 3

Abnormal Initial BPP Results:

• BPP score of 6 (equivocal): Repeat testing or use alternative antepartum test for reassurance, often scheduled weekly or twice weekly depending on clinical context 1
• BPP score ≤4 (abnormal): Immediate intervention typically required rather than repeat testing 1

Oligohydramnios:

• Amniotic fluid volume assessed at least weekly, but may require more frequent evaluation if approaching severely low levels 1
• Serial surveillance warranted in preterm pregnancies with oligohydramnios after thorough evaluation for causes 1

Integration with Other Surveillance Modalities

The BPP should not be used in isolation but integrated with other testing:

• Umbilical artery Doppler should guide surveillance frequency: every 2 weeks if normal, at least weekly if abnormal, and 2-3 times weekly with AEDV 1, 2
• Cardiotocography (CTG) is often the primary surveillance method, with BPP serving as adjunctive testing when CTG is nonreactive or concerning 1, 2
• Recent evidence suggests BPP becomes abnormal 48-72 hours after ductus venosus Doppler abnormalities in 90% of cases, making it a late indicator of compromise 1

Important Clinical Caveats

Limitations of BPP:

• The BPP is more specific than sensitive, performing well at identifying a healthy fetus but poorly at recognizing a fetus at risk for stillbirth 1
• A Cochrane review concluded that available evidence does not support the use of BPP as a test of fetal well-being in high-risk pregnancies due to high false-positive and false-negative rates 1
• In-hospital BPPs alter clinical decision making in less than 1% of cases 4

Gestational Age Considerations:

• Testing typically initiates at 32-34 weeks' gestation but should be individualized based on indication, gestational age, and likelihood of neonatal survival 1
• BPP interpretation should account for gestational age, as reactivity indicating favorable outcome is more common in near-term fetuses 5

When BPP Does NOT Predict Future Well-Being:

• The BPP score correlates over 90% with current fetal pH but does not predict future fetal well-being 6
• This emphasizes the importance of umbilical artery Doppler and amniotic fluid volume to determine appropriate surveillance frequency 6
• Antenatal surveillance cannot predict stillbirth related to acute events such as placental abruption or cord accidents 1

Practical Algorithm for Repeat Testing

1. Normal BPP (8/8 or 10/10): Repeat weekly for standard high-risk conditions 1
2. Normal BPP with FGR + normal umbilical artery Doppler: Weekly testing 1, 2
3. Normal BPP with FGR + abnormal umbilical artery Doppler: Twice-weekly testing 1, 2
4. Normal BPP with FGR + AEDV: Daily testing (1-2 times/day) 2, 3
5. Normal BPP with FGR + REDV: Daily testing (1-2 times/day) with consideration for delivery 2, 3
6. Equivocal BPP (6/8 or 6/10): Repeat same day or next day, or use alternative test 1
7. Abnormal BPP (≤4): Immediate intervention/delivery consideration rather than repeat testing 1

Critical Pitfall to Avoid: Do not rely solely on BPP for surveillance without integrating Doppler studies, as BPP abnormalities are late manifestations of placental disease 1, 6