Biophysical Profile (BPP): A Comprehensive Fetal Assessment Tool
The Biophysical Profile (BPP) is a standardized ultrasound-based assessment that evaluates four key parameters of fetal well-being: fetal breathing movements, fetal body/limb movements, fetal tone, and amniotic fluid volume, with an optional fifth component of non-stress test (NST) monitoring. 1
Components of the BPP
The BPP consists of the following components:
- Fetal breathing movements: Assessment of fetal respiratory efforts
- Fetal body/limb movements: Observation of discrete body or limb movements
- Fetal tone: Evaluation of fetal muscle tone and posture
- Amniotic fluid volume: Measurement of amniotic fluid, which reflects chronic fetal well-being
- Non-stress test (NST) (optional): Evaluation of fetal heart rate reactivity via cardiotocography
Each component receives a score of either 0 or 2, resulting in a maximum score of 8/8 (without NST) or 10/10 (with NST). A score of 8 or 10 strongly indicates a well-compensated fetus. 1, 2
Scoring System
| Parameter | Normal (Score 2) | Abnormal (Score 0) |
|---|---|---|
| Breathing movements | Present | Absent |
| Body/limb movements | Present | Absent |
| Fetal tone | Normal | Abnormal/absent |
| Amniotic fluid volume | Adequate | Reduced |
| NST (if included) | Reactive | Non-reactive |
Clinical Applications
The BPP is primarily used for:
High-risk pregnancy monitoring: Particularly valuable in cases of:
- Intrauterine growth restriction (IUGR)
- Maternal vascular disease (including preeclampsia)
- Suspected uteroplacental insufficiency
- Oligohydramnios or polyhydramnios
- Abnormal NST results requiring further evaluation
- Post-term pregnancy 2
Fetal well-being assessment: For those at risk for fetal demise, testing strategies typically evaluate one or more BPP parameters at least weekly, with increased frequency (twice weekly or daily) for higher-risk situations. 1
Multiple gestation monitoring: BPP can be performed in the third trimester to assess fetal well-being in multiple gestations, with frequency determined by risk factors and potential complications. 1
Interpretation and Management
- Score 8-10/10: Indicates normal fetal status with very low risk of fetal compromise
- Score 6/10: Equivocal, typically requires repeat testing within 24 hours
- Score 4/10 or less: Indicates potential fetal compromise, may warrant delivery depending on gestational age and other clinical factors
Limitations and Considerations
False reassurance: Despite a reassuring BPP score, a persistently abnormal NST may indicate fetal compromise, as demonstrated in cases of antepartum intracranial hemorrhage. 3
Evidence limitations: Cochrane review data does not strongly support BPP use over conventional monitoring in high-risk pregnancies, with no significant differences in perinatal deaths or low Apgar scores. Some evidence suggests increased cesarean section rates with BPP use. 4
Amniotic fluid assessment variability: Different methodologies for measuring amniotic fluid (1×1 cm pocket, 2×1 cm pocket, or 2×2 cm pocket) can significantly affect the diagnosis of oligohydramnios, potentially leading to different management decisions. 5
Testing frequency: For high-risk pregnancies, testing typically begins at 32-34 weeks' gestation with weekly or twice-weekly assessments, increasing in frequency with worsening maternal or fetal condition. 2
The BPP reduces the high false-positive rate characteristic of single-parameter testing methods like the NST alone, making it valuable for comprehensive fetal assessment in high-risk pregnancies. 6 However, clinicians should be aware of its limitations and consider it as part of a broader assessment strategy rather than in isolation.