Antenatal Hydronephrosis Management in Pediatric Urology

Antenatal hydronephrosis, defined as dilation of the fetal renal collecting system detected by routine obstetric ultrasound, affects around 1–4 % of pregnancies and presents a spectrum from transient pelvic dilatation to significant obstructive uropathy. Early identification enables stratified postnatal evaluation, combining standardised grading with functional imaging to distinguish cases requiring intervention from those suitable for observation. Severity assessment relies primarily on ultrasound parameters—anteroposterior diameter of the renal pelvis and calyceal dilation—integrated into classification schemes such as the Society for Fetal Urology (SFU) and Urinary Tract Dilatation (UTD) systems. Emerging refinements, notably the Onen grading, aim to reduce interobserver variability and improve prediction of renal damage. After birth, infants undergo serial ultrasound surveillance, complemented by functional studies—diuresis renography or magnetic resonance urography—to evaluate drainage curves and split renal function. Conservative management remains appropriate for mild grades that frequently resolve spontaneously, while progressive dilatation or deterioration in function prompts surgical correction, most commonly pyeloplasty for ureteropelvic junction obstruction. Recent advances in imaging technology, automated grading and long-term outcome data have strengthened evidence-based protocols. A global consensus on optimal follow-up intervals, intervention thresholds and integration of novel risk markers continues to evolve, with an emphasis on minimising unnecessary surgery while preventing irreversible nephron loss.

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Antenatal Hydronephrosis Management in Pediatric Urology publication trend

The graph below shows the total number of articles in antenatal hydronephrosis management in pediatric urology across all publications each year (not limited to Nature Index journals).

Technical terms

Antenatal hydronephrosis: Dilatation of the foetal renal pelvis or calyces identified on prenatal ultrasound.

Society for Fetal Urology (SFU) grading system: A scale from 0 to IV classifying hydronephrosis severity by calyceal appearance and parenchymal thinning.

Urinary Tract Dilatation (UTD) classification: Consensus framework integrating antenatal and postnatal ultrasound findings to stratify risk of urinary tract abnormalities.

Onen grading system: An alternative hydronephrosis classification that distinguishes specific parenchymal changes and guides intervention thresholds.

Ureteropelvic junction obstruction (UPJO): A congenital narrowing at the junction of the renal pelvis and ureter, a leading cause of persistent antenatal hydronephrosis.

Pyeloplasty: Surgical reconstruction of the ureteropelvic junction to relieve obstruction and preserve renal function.

References

1. Grading of Hydronephrosis: An Ongoing Challenge. Frontiers in Pediatrics (2020).
2. Clinical Outcome of Children With Antenatally Diagnosed Hydronephrosis. Frontiers in Pediatrics (2019).
3. Using Deep Learning Algorithms to Grade Hydronephrosis Severity: Toward a Clinical Adjunct. Frontiers in Pediatrics (2020).
4. The SNMMI and EANM Procedural Guidelines for Diuresis Renography in Infants and Children. Journal of Nuclear Medicine (2018).
5. Comparative Study Between Functional MR Urography and Renal Scintigraphy to Evaluate Drainage Curves and Split Renal Function in Children With Congenital Anomalies of Kidney and Urinary Tract (CAKUT). Frontiers in Pediatrics (2020).
6. Diagnostic accuracy of Onen’s Alternative Grading System combined with Doppler evaluation of ureteral jets as an alternative in the diagnosis of obstructive hydronephrosis in children. PeerJ (2018).
7. Antenatally detected urinary tract dilatation: a 12–15-year follow-up. Pediatric Nephrology (2020).
8. Prenatal Diagnosis and Findings in Ureteropelvic Junction Type Hydronephrosis. Frontiers in Pediatrics (2020).