Antenatal hydronephrosis: infants with minor postnatal dilatation do not need prophylaxis

Area of Science:

• Pediatric Nephrology
• Neonatal Imaging
• Infectious Diseases

Background:

• Antenatal renal pelvis dilatation (ARPD) is a common finding in fetal ultrasounds.
• The risk of urinary tract infection (UTI) in infants with ARPD requires further investigation.
• Postnatal ultrasound (US) and voiding cystourethrography (VCUG) are used to assess ARPD and associated urinary tract abnormalities.

Purpose of the Study:

• To determine the incidence of UTI in infants diagnosed with ARPD.
• To evaluate the correlation between postnatal US findings and UTI occurrence.
• To assess the necessity of routine antibacterial prophylaxis in infants with ARPD.

Main Methods:

• Screening 14,000 pregnant women identified 106 fetuses with ARPD (≥5 mm).
• Infants underwent two postnatal US examinations and VCUG at 6-8 weeks.
• Follow-up for 2 years, with antibacterial prophylaxis for specific high-risk cases (RPD ≥15 mm, VUR grades III-V, suspected obstruction).

Main Results:

• 53/103 infants had normal postnatal US; only 2 (both girls) developed UTI late (18 and 24 months).
• 50 infants had abnormal initial US; 6 had vesicoureteric reflux (VUR), including 4 with high-grade VUR (IV-V).
• All 4 infants with high-grade VUR developed UTI.

Conclusions:

• UTI is infrequent in infants with ARPD who exhibit normal postnatal US findings.
• High-grade VUR is a significant risk factor for UTI development in this cohort.
• Routine antibacterial prophylaxis is not warranted for infants with ARPD and normal postnatal US evaluations.