Biophysical Profile
last authored: July 2011, David LaPierre
last reviewed: Oct 2011, Bonnie Inns
Introduction
The biophysical profile (BPP) is an ultrasound-based assessment of fetal health. It requires an ultrasound machine with Doppler, and typically takes up to 30-60 minutes to complete. It measures five parameters, each scored 0 or 2: fetal tone, breathing, movement, amniotic fluid volume, and heart rate accelerations (non-stress test [NST]).
Scoring the BPP
Variable |
2 |
0 |
nonstress test |
at least two accelerations of >15 beats/min for >15 sec |
0-1 accelerations |
fetal breathing |
at least one episode of rhythmic breathing lasting 30 sec |
< 30 sec of breathing |
fetal movement |
at least three limb or body movements |
< 3 movements |
fetal tone |
at least one episode of limb extension and then flexion |
no extension/flexion |
amniotic fluid volume |
a fluid pocket of at least 2 cm |
insufficient fluid to meet this criteria |
In general,
- score of 8-10 is suggests no cause for concern
- score of 6 is ambiguous
- score of 2-4 is concerning for hypoxia and acidosis.
- score of 0 is very worring. Immediate delivery should be strongly considered.
Studies have been done correlating BPP score with fetal acidosis. A score of 0 was very suggestive of acidemia, while 8-10 appeared normal. A score of 6 is very ambiguous, while 2-4 has somewhat stronger predictive value (Manning et al, 1993). However, a 2008 Cochrane review (Lalor et al) has found there is insufficient evidence to use the BPP as a test for fetal well-being in high-risk pregnancies, given it's lack of predictive value.
Modified BPP
A modified biophysical profile may also be carried out, using NST and amniotic fluid index. Amniotic fluid index (AFI) is the sum of the largest cord-free amniotic fluid pockets in each of the abdominal quadrants. Normal is >5 cm.
The American College of Obstetricians and Gynecologists, as well as the American Academy of Pediatrics, have stated that the modified BPP is as satisfactory as the full BPP for predicting fetal well-being (ACOG and AAP, 2007).
Resources and References
American College of Obstetricians and Gynecologists, American Academy of Pediatrics. 2007. Guidelines for Perinatal Care. 6th Ed.
Lalor JG et al. 2008. Biophysical profile for fetal assessment in high-risk pregnancies. Chchrane Database Syst Rev. CD000038.
Manning FA et al. 1993. Fetal biophysical profile score IV: correlation with antepartum umbilical venous fetal pH. AJOG. 169:755.
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