Prenatal sonographic predictors of postnatal pyeloplasty in fetuses with isolated hydronephrosis

Objective To define prenatal sonographic predictors of ureteropelvic junction obstruction requiring postnatal pyeloplasty, in fetuses with isolated hydronephrosis. Methods Retrospective data on prenatal sonographic parameters were compared between patients who had been diagnosed prenatally with hydronephrosis and either underwent postnatal pyeloplasty for ureteropelvic junction obstruction (n = 39) or were treated conservatively (n = 30). Results Significant differences between the surgically and conservatively treated patients were found for mean anterior–posterior renal diameter (22.8 ± 8.6 vs 14.2 ± 5.9 mm, respectively, p 14 mm was the best single predictor of the need for surgery (area under the ROC curve, 0.817), with sensitivity 77%, specificity 69%, positive predictive value (PPV) 77% and negative predictive value (NPV) 69% (β = 1.17, 95%CI = 1.07–1.28, p 2.1 had a sensitivity of 87% and specificity of 65% for the need for surgery (area under the curve 0.822, PPV 79%, NPV 77%; β = 1.92, 95%CI = 1.16–3.17, p 2.1 of pelvic anterior–posterior diameter to parenchymal thickness suggests ureteropelvic junction obstruction and supports the use of more intensive prenatal and postnatal surveillance. © 2014 John Wiley & Sons, Ltd. What's already known about this topic? Obstetrical ultrasound specialists currently have limited tools to help them distinguish between fetal ureteropelvic junction obstruction and transient hydronephrosis during pregnancy. Anterior–posterior diameter of the renal pelvis is the most studied sonographic parameter for the diagnosis of prenatal hydronephrosis, together with parenchymal thickness, renal length and calyceal dilatation. However, there are no standardized pathological thresholds for these parameters that suggest definite obstruction. What does this study add? The results of this study imply that anterior–posterior diameter of the renal pelvis is the strongest single predictor for pyeloplasty in fetuses with isolated hydronephrosis. Parenchymal thickn