Comparative efficacy of umbilical arterial Doppler indices for predicting adverse perinatal outcome

A variety of descriptor indices for the umbilical arterial Doppler waveform are currently in use for predicting perinatal outcome. However, there is a paucity of data regarding the relative diagnostic merits of these indices. We addressed this issue in a prospective, blind study in which the diagnostic efficacy of the following Doppler indices was compared: resistance index, systolic/diastolic ratio, pulsatility index, and diastolic average ratio. The analytic technique consisted of the receiver operating characteristic method, which evaluates a test's ability to discriminate a diseased from a healthy population. The patient population consisted of 350 pregnant patients with gestational ages of 34 to 36 weeks. A continuous-wave Doppler device with a 4 MHz transducer was used to investigate the umbilical vessels. The test was performed only once in each patient. The abnormal outcome parameters included small for gestational age (less than 10th percentile), Apgar score less than 7 at 5 minutes, fetal distress (late and severe variable decelerations, absent variability, fetal scalp pH less than 7.20), umbilical cord arterial pH less than 7.10, presence of thick meconium, and admission to neonatal intensive care unit (greater than 48 hours). The results showed that the resistance index had the best discriminatory ability when compared with other Doppler indices: the systolic/diastolic ratio (p less than 0.05), the pulsatility index (p less than 0.001), and the diastolic/average ratio (p less than 0.05). It is concluded that of the various Doppler indices assessed in this investigation, the resistance index offers the best diagnostic efficacy in predicting perinatal compromise.