Biophysical profile

Ultrasound

A biophysical profile is a prenatal ultrasound evaluation of fetal well-being, involving a scoring system. It is often done when a non-stress test is non reactive, or for other obstetrical indications.

The test

The biophysical profile (BPP) has 5 components: 4 ultrasound (US) assessments and a nonstress test (NST). The nonstress test (NST)(CTG) evaluates fetal heart rate and response to fetal movement. The five discrete biophysical variables:

1. Fetal movement
2. Fetal tone
3. Fetal breathing
4. Amniotic fluid volume
5. Fetal Heart Rate

Parameter	Normal (2 points)	Abnormal (0 points)
NST/Reactive FHR	At least two accelerations in 30 minutes	Less than two accelerations to satisfy the test in 30 minutes
US: Fetal breathing movements	At least one episode of > 30s[citation needed] or >20s in 30 minutes	None or less than 30s[citation needed] or 20s
US: Fetal activity / gross body movements	At least two movements of the torso or limbs	Less than three[citation needed] or two movements
US: Fetal muscle tone	At least one episodes of active bending and straightening of the limb or trunk	No movements or movements slow and incomplete
US: Qualitative AFV/AFI	At least one vertical pocket> 2 cm or more in the vertical axis	Largest vertical pocket</=2cm

Use of acoustic stimulation to accelerate evaluation has been described.

Scoring

Each assessment is graded either 0 or 2 points, and then added up to yield a number between 0 and 10. A BPP of 8 or 10 is generally considered reassuring. A BPP normally is not performed before the second half of a pregnancy, since fetal breathing movements do not occur in the first half.

The presence of these biophysical variables implies absence of significant central nervous system hypoxemia/acidemia at the time of testing. By comparison, a compromised fetus typically exhibits loss of accelerations of the fetal heart rate (FHR), decreased body movement and breathing, hypotonia, and, less acutely, decreased amniotic fluid volume.