AIM: To define a better cut-off value of the renal pelvis anteroposterior diameter (RPAPD) to predict persistent or progressive pyelectasis during pregnancy. METHODS: We retrospectively reviewed 8873 women whose fetal RPAPD was measured. Midtrimester pyelectasis was defined as a RPAPD of ≥4 mm. Persistent/progressive pyelectasis was defined as a RPAPD of ≥10 mm before delivery. A RPAPD cut-off value to predict a persistent/progressive pyelectasis was determined by receiver operating characteristic curve analysis. RESULTS: Among 249 isolated cases of pyelectasis, persistent/progressive pyelectasis was found in 6.9% before delivery. The midtrimester RPAPD cut-off value that best predicted persistent/progressive pyelectasis before delivery was ≥6 mm with sensitivity, specificity, positive and negative predictive values of 64.3%, 88.7%, 30.0%, and 97.1%, respectively. CONCLUSIONS: Although most cases of midtrimester fetal pyelectasis regress to normal during pregnancy, those with a RPAPD of ≥6 mm in the midtrimester are at higher risk for persistent or progressive pyelectasis.
AIM: To define a better cut-off value of the renal pelvis anteroposterior diameter (RPAPD) to predict persistent or progressive pyelectasis during pregnancy. METHODS: We retrospectively reviewed 8873 women whose fetal RPAPD was measured. Midtrimester pyelectasis was defined as a RPAPD of ≥4 mm. Persistent/progressive pyelectasis was defined as a RPAPD of ≥10 mm before delivery. A RPAPD cut-off value to predict a persistent/progressive pyelectasis was determined by receiver operating characteristic curve analysis. RESULTS: Among 249 isolated cases of pyelectasis, persistent/progressive pyelectasis was found in 6.9% before delivery. The midtrimester RPAPD cut-off value that best predicted persistent/progressive pyelectasis before delivery was ≥6 mm with sensitivity, specificity, positive and negative predictive values of 64.3%, 88.7%, 30.0%, and 97.1%, respectively. CONCLUSIONS: Although most cases of midtrimester fetal pyelectasis regress to normal during pregnancy, those with a RPAPD of ≥6 mm in the midtrimester are at higher risk for persistent or progressive pyelectasis.