Umbilical artery velocimetry and non-stress test in monitoring high-risk pregnancies. A comparative longitudinal study.

Abstract

In a longitudinal comparative study, umbilical artery velocimetry and the non-stress test were used in parallel for surveillance of 153 hospitalized high-risk pregnancies. The occurrence of abnormal flow velocity waveforms of the umbilical artery, with increased pulsatility index but maintained diastolic flow velocity, was an inconsistent finding and often related to pregnancy complications other than intrauterine growth retardation. Among patients with small-for-gestational age fetuses or pre-eclampsia with a small-for-gestational age fetus, there was a significantly higher frequency of abnormal umbilical flow velocity waveforms. This was a consistent finding and was often associated with an absence of diastolic flow velocity and operative delivery for fetal distress. An abnormal non-stress test had a significant relationship with intrauterine growth retardation, but a lower predictive capacity for this condition than the abnormal umbilical artery flow velocity waveform. In patients with small-for-gestational age fetuses and no other complication of pregnancy, umbilical artery velocimetry can be used as a reliable tool for identifying those fetuses that need intensified surveillance. In cases with additional complications, a combined use of blood velocimetry and the non-stress test is advocated.