Pulsed Doppler umbilical artery waveforms: significance of elevated umbilical artery systolic/diastolic ratios in the normally grown fetus

Previous studies have demonstrated a high correlation between elevated resistance in the placental circulation, evidenced by abnormal umbilical artery systolic-to-diastolic (S/D) ratios, and the subsequent birth of a small for gestational age (SGA) infant. However, few data exist on the significance of elevated S/D ratios for pregnancies in which outcome does not involve an SGA infant. Pulsed Doppler spectral recordings and level II ultrasound examinations were performed 373 times in 256 referred high-risk patients. Doppler data were not used for patient management decisions. Thirty-two women with elevated umbilical artery S/D ratios of 4.5 or greater (defined as abnormal regardless of gestational age) gave birth to non-SGA infants. The ultrasound characteristics and outcome for this group were compared with those of 200 patients who were also non-SGA but who exhibited normal waveforms and with 24 SGA infants with predominantly abnormal waveforms. Thirty-one percent of the non-SGA infants with abnormal waveforms had structural malformations, a rate significantly higher (P less than or equal to .03) than the 18% malformation rate in the normal-waveform group. Further, the stillbirth rate and number of terminations of pregnancy for lethal anomalies were five times greater in the non-SGA group with abnormal waveforms than in the non-SGA group with normal waveforms (P less than or equal to .001). A wide variety of structural malformations was observed in the abnormal-waveform group, most frequently involving the central nervous system. Amniotic fluid volume tended to be decreased in the SGA group, whereas increased amniotic fluid volume or hydramnios was seen in 23% of the non-SGA abnormal-waveform group.