Outcome of Neonatal Hydronephrosis, a New Cut-Off to Identify Patients with Spontaneous Resolution

Area of Science:

• Pediatric Nephrology
• Diagnostic Imaging
• Neonatal Care

Background:

• Urinary tract dilatation (UTD) is a common finding in newborns.
• Assessing the severity of UTD is crucial for appropriate management.
• Current methods for stratifying UTD risk and predicting outcomes are not standardized.

Purpose of the Study:

• To establish cut-off values for anteroposterior renal pelvis diameter (APRPD) at birth.
• To stratify the risk of complications associated with postnatal UTD.
• To guide the need for second-level examinations in neonates with UTD.

Main Methods:

• Retrospective analysis of 500 newborns with unilateral or bilateral UTD diagnosed via ultrasound between 2010 and 2020.
• Inclusion of infants undergoing follow-up examinations at 3, 6, 12, and 24 months.
• Statistical analysis to determine APRPD cut-offs for outcome prediction.

Main Results:

• A median APRPD of 7.7 mm was observed in the first two months of life.
• Spontaneous UTD resolution occurred in 70.6% of cases by 24 months.
• An APRPD value ≤ 8.5 mm demonstrated 80.4% sensitivity and 100% specificity for predicting resolution within 24 months.
• APRPD ≤ 8.5 mm was an independent predictor of 24-month resolution (p=0.000).

Conclusions:

• Isolated hydronephrosis is the most frequent urinary tract anomaly detected prenatally.
• An 8.5 mm APRPD cut-off can help reassure clinicians and parents regarding benign postnatal dilatation.
• This finding supports a structured approach to managing neonatal UTD.