Uterine artery pulsatility index less than 1.0 as an isolated marker in predicting low-risk subjects for preeclampsia

Background: Preeclampsia is one of the major obstetric vasculopathies. As the treatment of the cause of preeclampsia remains elusive, its prediction is much sought after. In this study the authors have tried to evaluate a relatively unstudied parameter of PI<1.0 in prediction of low-risk subjects for preeclampsia.Methods: Subjects enrolled for the study were prospectively and longitudinally studied clinically and through colour Doppler for changes in values I-trimester and II-trimester of pregnancy. The techniques used were as described by Clinical Standards Committee. First uterine artery scan was obtained between 11 to 14 weeks of pregnancy (I-Trimester scan). Second scan of the same woman was obtained between 20-22 weeks of pregnancy (II-Trimester scan). All such enrolled subjects were serially followed up to delivery and their obstetric outcome noted especially for development of preeclampsia. Data was carefully recorded and analysed using online statistical software.Results: It was found that those subjects who had PI<1 in II-trimester, have a significantly less chances of developing PIH (P value being<0.05). But when PI<1.0 in I-trimester was analysed; it was found that the difference between those who developed PIH and those who did not was not statistically significant. Nevertheless, PI<1.0 in I-trimester had an excellent specificity and positive predictive value.Conclusions: Pulsatility Index if<1.0 in II-trimester in any pregnant woman on colour Doppler indicates a low-risk subject for preeclampsia. In such subjects preventive medications like aspirin or aspirin + heparin combination can be safely stopped.