The receiver-operator characteristic (ROC) curve for the different values of the pulsatility index concerning the discrimination between groups II and III. All the values from 1 to 8 in increments of 0.5 are identified in the curve with a circle. The point in the curve that is closer to the upper-left corner of the plot corresponds to the value 2.808 of the pulsatility index. At that cut-off point, the sensitivity and specificity values of the pulsatility index in the uterine artery were of 69.5%( CI 95%: 61.5%-76.5%) and 75.0%( CI 95%: 57.9%-86.8%), respectively; the area under the curve (AUC) was 0.734 (0.648-0.819). The correspondent positive and negative predictive values were 92.5% and 35.8%, respectively. The likelihood ratio (LR) for a positive or negative test was 2.78 (CI 95%: 1.51%-5.12%) or 0.41 (CI 95%: 0.30%-0.56%), respectively.