Ultrasound Observations in the Normal Intrapartum Patient: Assessment of the Biophysical Profile Score and Doppler Velocimetry

Abstract

The ultrasound assessment of fetal health using the biophysical profile score (BPS) and Doppler velocimetry, either alone or in combination, are standard methods of surveillance in the high-risk antenatal patient. There has been limited utilization of these tests during labor, and there are theoretical reasons why the intrapartum milieu may alter test outcome. We believed that it was important to evaluate both tests in normal intrapartum patients before considering applications in complicated pregnancies.

In a prospective cross-sectional study in 76 low-risk patients we documented a normal BPS in 93.3% of patients in latent labor, 82.3% in early active labor, and 70% in late active labor. There were no significant changes in 3 of the 4 BPS parameters as labor progressed. However, a decrease in fetal breathing movements was noted as labor progressed, from 37% in the latent phase of labor to 10% in the active phase of labor. The status of the amniotic membranes did not influence the finding of normal amniotic fluid volume. We continued to study these patients with Doppler velocimetry of major fetal vessels with and without uterine contractions. We observed that the systolic/diastlic ratio in the umbilical artery, fetal aorta, and IVC did not alter with contractions and that our results were similar to normal antepartum values. These data provide information on functional ultrasound findings in the nonasphyxiated intrapartum fetus, and may serve as a guideline when studying the complicated pregnancy.

Key Words:

• Intrapartum
• Ultrasound
• Biophysical profile score
• Doppler
• Velocimetry