What type of test is utilized for determining reactive fetal heart rate in a biophysical profile?

The non-stress test (NST) is specifically designed to assess the fetal heart rate in relation to fetal movement, effectively indicating the well-being of the fetus. During this test, the fetal heart rate is monitored while the mother is instructed to report any fetal movements. A reactive result is indicated by the fetal heart rate accelerating in response to movement, which suggests that the fetus is receiving adequate oxygen and is functioning normally.

In the context of a biophysical profile, the NST plays a critical role in determining fetal health. Other components of the biophysical profile, such as fetal movements, tone, and amniotic fluid volume, are assessed concurrently with the NST. This combination allows for a comprehensive evaluation of the fetus's condition.

While ultrasound is utilized to evaluate anatomical features and assess factors like amniotic fluid levels and fetal biometry, it does not specifically measure heart rate reactivity in the way that an NST does. Amniocentesis and chorionic villus sampling are invasive procedures primarily used for genetic testing and assessing certain conditions but do not assess fetal heart rate or movement. Thus, the non-stress test is the most appropriate choice for determining reactive fetal heart rate within the context of a biophysical profile.