Cerebroplacental Doppler ratio and adverse perinatal outcomes in intrauterine growth restriction - Evaluating the impact of using gestational age-specific reference values

Objective. The purpose of this study was to compare the impact of using gestational age-specific reference levels of the cerebroplacental Doppler ratio (CPR) with categorical threshold in the prediction of adverse perinatal outcomes in growth-restricted pregnancies. Methods. A retrospective cohort study of cases of intrauterine growth restriction over a 3-year period was conducted. The umbilical artery and middle cerebral artery pulsatility indices were converted to CPRs. The efficacy of using gestational age-specific reference levels of CPRs in predicting adverse outcomes was compared with the use of a CPR of less than 1.08. Adverse perinatal outcomes evaluated included cesarean delivery for nonreassuring fetal heart tones, umbilical artery pH less than 7.0, 5-minute Apgar scores less than 7.0, intraventricular hemorrhage greater than grade 2, periventricular leukomalacia, respiratory distress syndrome, and perinatal death. Results. Of 183 pregnancies meeting our inclusion criteria, there were 70 with at least 1 adverse outcome. With the use of a CPR ratio below the 5th percentile for gestational age, the sensitivity, specificity, and positive and negative predictive values for predicting an adverse outcome were 65 %, 73 %, 73 %, and 65 %, respectively, with an odds ratio (95 % confidence interval) of 5.2 (1.4-19.4; area under the receiver operating characteristic curve, 0.69). With a CPR threshold of less than 1.08, the sensitivity, specificity and positive and negative predictive values were 72 %, 62 %, 68 %, and 67 %, with an odds ratio (95 % confidence interval) of 4.2 (1.2-15.3; area under the receiver operating characteristic curve, 0.67). Conclusions. An abnormal CPR is associated with adverse perinatal outcomes in growth-restricted fetuses. The accuracy of using gestational age-specific reference levels was similar to that of using a categorical threshold.