Ductus Venosus S-Wave/Isovolumetric A-Wave (SIA) Index and A-Wave Reversed Flow in Severely Premature Growth-Restricted Fetuses

Abstract

Ductus venosus (DV) Doppler waveforms show 2 periods of decreased velocity during iso-volumetric relaxation (isovolumetric relaxation velocity [IRV]) and atrial contraction (A wave or end-diastolic velocity [EDV]). In intrauterine growth-restricted (IUGR) fetuses, both may become abnormal. The hypothesis for this study was that in severely premature IUGR fetuses, Doppler assessment of both the IRV and EDV allows a more accurate prediction of fetal outcome than absent/reversed end-diastolic flow (A/REDF) alone. Ductus venosus Doppler waveforms were serially studied in 49 severely premature IUGR fetuses from diagnosis until death or delivery. The DV waveforms were assessed for peak systolic velocity (PSV), IRV, and EDV and qualitatively for forward end-diastolic flow or A/REDF. The S-wave/isovolumetric A-wave (SIA) index [PSV/(IRV + EDV)] for each fetus was compared to fetal/neonatal outcomes. There were 8 cases of fetal death (FD), 9 cases of neonatal death (ND), and 32 cases of neonatal survival (NS). A receiver operating characteristic (ROC) curve for the SIA index in all cases showed that values less than -1.25 correlated with FD and those greater than -1.25 correlated with live birth, with 100% sensitivity and 100% specificity. A second ROC curve of live births showed that values less than 2.07 correlated with NS and those greater than 2.07 correlated with ND with 67% sensitivity and 94% specificity. Ductus venosus A/REDF correlated with FD, ND, and NS with sensitivity values of 88%, 78%, and 32%, respectively. Of the 32 NSs, 11 (34%) had A/REDF with a median of 11 days before delivery. The SIA index is a novel Doppler parameter for assessment of severely premature IUGR fetuses that allows a much more accurate prediction of fetal outcome compared to A/REDF alone.