Figure 1. Receiver operating characteristic (ROC) plot for prediction of miscarriage using yolk sac size. The ROC plot was used to define the best cutoff value of yolk sac size, which was >0.56, with a sensitivity of 78.6%, specificity of 84.3%, positive predictive value of 74.7%, negative predictive value of 87.1%, and diagnostic accuracy of 78.2%.