EP12.37: The value of 2D and 3D bladder volume measurement in the prediction of spontaneous resolution of prenatal hydronephrosis

Abstract

To assess whether fetal bladder volume can be used in the prediction of spontaneous resolution of prenatal hydronephrosis (PNH) and to determine the feasibility of measuring bladder volume using three-dimensional (3D) ultrasound, in comparison with two-dimensional (2D) bladder measurement. Receiver operating characteristic (ROC) analysis was used to assess the diagnostic accuracy of 2D bladder volume in predicting prognosis in PNH. Virtual organ computer-aided analysis (VOCAL) was performed to calculate 3D bladder volume for cases where 3D measurements were available and then 2D and 3D bladder volume measurement agreement was determined using a paired t-test and difference against the mean plots. ROC analysis showed that 2D bladder volume could not predict the spontaneous resolution of PNH for the 42 cases included. Gestational age, at first diagnosis of PNH, could predict prenatal resolution; area under the ROC curve (AUC) = 0.83 (95% confidence interval (CI) 0.70 - 0.95) and postnatal resolution within the first few weeks of birth; AUC = 0.76 (95% CI 0.61 - 0.91). There was a correlation between gestational age and bladder volume, with a 25% increase in bladder volume for each week gestation (95% CI 21- 30%). 2D and 3D bladder volume measurements showed acceptable agreement in the 17 cases included. 2D Bladder volume measurement agrees with 3D measured using VOCAL software and is unable to predict the spontaneous resolution of PNH. Interestingly, PNH diagnosed at earlier gestational age resolved prenatally or by the first weeks of life, questioning the need for multiple prenatal scans which increase parental anxiety and use limited medical resources. Further research to validate these results and reduce the limitations of this retrospective pilot study is warranted.