How can we measure the renal pelvic anteroposterior diameter in postnatal isolated hydronephrosis?

Predicting clinically significant events in children with ureteropelvic junction obstruction

Introduction

Ureteropelvic junction obstruction (UPJO) syndrome is one of the most common causes of neonatal hydronephrosis. Management varies from simple monitoring to surgical intervention, with indications differing between institutions. A consensus of 8 societies recently described a new Urinary Tract Dilation (UTD) classification which aims to standardize ultrasound description of hydronephrosis, but which is also supposed to have predictive value in children with hydronephrosis. Our aim was to compare, in a monocentric prospective cohort of children with UPJO, the ability of UTD to predict the occurrence of a clinically significant event within the first year of life, as compared to anteroposterior diameter of the renal pelvis (APD).

Study design

We used a preexisting cohort of children followed in a prospective study on UPJO. A pediatric radiologist, blinded to the children's outcome, classified the last antenatal ultrasound and postnatal ultrasound according to the UTD-A and UTD-P classification. He also confirmed the APD-A and APD-P measures. We defined a clinically significant event as being: increased pelvic dilation (>5 mm) and/or the presence of a febrile urinary tract infection (fUTI) and/or impaired renal function on initial nuclear scan (<40%). We performed a ROC-AUC curve and Random Forest (RF) analysis to compare the ability of the APD-A, APD-P, UTD-A and UTD-P scores to predict a clinically significant event.

Results

The cohort included 28 children. Clinically significant events were noted in 20 out of 28 patients: 13 children presented an increase >5 mm in dilation, 6 presented an episode of fUTI and 9 had impaired function of the affected kidney. APD-A was the most effective individual criterion for predicting the occurrence of a significant clinical event (AUC = 0.867).

Conclusion

In our series, for children with UPJO, the most significant marker was prenatal APD >15 mm to predict an increase in dilation >5 mm.

Significant improvement in hydronephrosis with pyeloplasty prior to 3 months of age in patients with antenatal severe hydronephrosis

INTRODUCTION

Pyeloplasty is the definitive management of ureteropelvic junction obstruction (UPJO). One of the challenging questions is when to perform pyeloplasty. We studied if improvement post-pyeloplasty in the first 3 months of life could show greater improvement in hydronephrosis than surgery at an older age.

PATIENTS AND METHODS

Patients with postnatally diagnosed UPJO and underwent pyeloplasty in the first year of life were retrospectively reviewed. We excluded patients with concomitant vesicoureteral reflux, and patients who had pyeloplasty because of UTI or missed follow-up. Patients were divided into two groups, according to the age at pyeloplasty, before and after the age of 3 months. We collected patients' demographics, anteroposterior diameter of the renal pelvis (APD), SFU grade, renogram data, perioperative data (surgery duration, hospital stay, and ureteral stent duration) and postoperative ultrasound changes. The percentage of change of APD (Δ%APD) was calculatedusing the formula: Δ%APD = [ (initial APD-last APD)/initial APD] *100.

RESULTS

We included 90 patients (93 renal units). 36 patients had pyeloplasty during the first 3 months of life and 57 patients at 3 -12 months. Patients' characteristics were similar in both groups except APD which was higher when pyeloplasty was done < 3 months of age (p = 0.02). Both groups had comparable perioperative parameters. After almost similar follow-up period of both groups. The Δ%APD was 58% when pyeloplasty was done < 3 months compared to 33% when was performed > 3 months (p = 0.009). Using Kaplan-Meier analysis, APD significantly improved when pyeloplasty was performed before the age of 3 months (p = 0.001).

CONCLUSION

Early pyeloplasty, in the first 3 months of life, showed a significant improvement of APD postoperatively than those had surgery later. It is unclear if this will relate to less loss of renal function yet certainly this would be suspected and feel this finding provides some evidence for early intervention.