Biophysical Tests

A number of noninvasive tests can be used to evaluate the well-being of the fetus.



The Non-stress Test (NST): the NST involves monitoring the fetus's heart rate with the fetal heart rate monitor (an external, noninvasive tool) and looking for fetal heart rate accelerations (see picture above) associated with fetal movement of uterine contractions. When these are present it indicates that the fetus is in good shape. If fetal heart rate accelerations are not present, it does not necessarily mean that the fetus is in trouble. Fetuses are frequently asleep; and when they are asleep their heart rate does not accelerate. The nurse may, therefore, need to stimulate the fetus with a safe hand-held device or may ask the patient to return for another test after lunch (which may awaken the fetus).

Biophysical Profile (BPP): the BPP is a more detailed evaluation of the fetus using the NST and ultrasound to study the unborn infant. In addition to the NST, an ultrasound examination of the fetus will be done to look at the amount of amniotic fluid around the baby, to evaluate whether or not the fetus is moving and breathing, and to look at the fetus's muscle tone. In some instances, a Modified Biophysical Profile (MBPP) may be done instead of the full BPP. This test looks at only the NST and amount of amniotic fluid. When both are normal the MBPP is as accurate as the full BPP.

Doppler Blood Flow Studies: this test uses a form of ultrasound to measure blood flowing through the various fetal or maternal blood vessels. By using this form of ultrasound, the physician can determine if the placenta (afterbirth) is functioning normally or if there is any sign of fetal heart failure.