Biophysical Profile (BPP)
The biophysical profile is a test performed to determine whether your baby is receiving enough oxygen or not--in essence, your baby's wellbeing. This test is given to women whose:
pregnancies are considered high risk (those with diabetes or high blood pressure--either preexisting or pregnancy induced, or preeclampsia),
babies may have a diagnosis of IUGR (intrauterine growth retardation),
babies are less active than normal
pregnancies contain too much or too little amniotic fluid
due dates are past (overdue)
previous pregnancy/pregnancies have ended in a loss during the second half of pregnancy
Usually administered in the third trimester, the biophysical profile is a series of tests (a detailed ultrasound and a non-stress test) designed to target five components--the baby's body movements, muscle tone, amniotic fluid, breathing movements, and heartrate. During the 30 minute ultrasound, the first four components will be assigned a score of 0 (abnormal) to 2 (normal). If the baby scores normal across the board, the non-stress test part of the BPP may be skipped.
To achieve a normal score the tests must show:
Body movements--baby should move 3 or more different limbs during the test.
Muscle tone--baby should be able to flex a finger/toe and open and close his/her hand
Amniotic Fluid--uterus should contain a pocket of amniotic fluid more than 2 centimeters wide.
Breathing--baby should have one or more times where breathing movements are noted for 30 seconds or more.
Heartrate (if non-stress test is performed)--
your baby's heart rate increases at least twice in 20 minutes,
the accelerations increase by at least 15 beats for 15 seconds,
and when heart accelerations are related to his/her movements.
If the baby scores abnormal on any of the scores*, the non-stress test will be administered, also gaining a score of 0 (abnormal) to 2 (normal) for heart rate. (*However, if the score for amniotic fluid should be a 0, the provider will probably want to induce immediately, regardless of the other scores.)
The scores are then combined to give a score ranging from 0 to 10. Typically, scores of 8-10 are considered normal; any scores at seven or below will be grounds for either further testing or induction. (If the baby is not full term, the risks should be weighed carefully before inducing; when results are borderline or ambiguous, it is common for the BPP to be repeated multiple times a week). Repeating of the BPP typically will show babies whose environments are deteriorating as abnormal umbilical cord flow patterns show first, followed by slowed fetal heart rate, loss of breathing movements, and loss of muscle movements and tone, consecutively.
This test has a low false negative rate of <1 per 1000. Risks of both the ultrasound and non-stress test should be reviewed as they are what the BPP consists of; the ultrasound and non-stress tests, each by itself, may have higher false positives indicating fetal distress, but together the data seems to confirm or negate the diagnosis in most instances. Though the likelihood of having a false positive has been significantly reduced because of the "checks and balances" of each test done together, erroneous interpretation of results still probably remains the highest risk of the BPP, for the results of an abnormal BPP will almost always lead to further testing or medical interventions. (cesarean sections, induction, etc.)
Modified Biophysical Profile
Some practitioners elect to use the Modified Biophysical Profile which consists of the non-stress test combined with the measuring of the amniotic fluid levels. If either of these tests appear abnormal, it is likely that a complete Biophysical Profile or Oxytocin Challenge test will be recommended to further assess the situation. In cases of severe distress, immediate delivery may be warranted. The accuracy of the modified biophysical profile results/scores appear to be comparable to the complete BPP in most instances. Risks from the test are comparable as well.