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Congenital hydronephrosis
Guidelines
Key sources
The following summarized guidelines for the evaluation and management of congenital hydronephrosis are prepared by our editorial team based on guidelines from the European Association of Urology (EAU/ESPU 2025), the American College of Radiology (ACR 2024,2020), the Canadian Urological Association (CUA/PUC 2018), the American Urological Association (AUA 2017), and the American Academy of Pediatrics (AAP 2016).
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Classification and risk stratification
Assessment of antenatal hydronephrosis: as per Pathway 2025 guidelines, classify the severity of antenatal hydronephrosis based on anteroposterior renal pelvic diameter:
Situation
Guidance
Mild
4-7 mm in the second trimester
7-9 mm in the third trimester
Moderate
7-10 mm in the second trimester
9-15 mm in the third trimester
Severe
7-10 mm in the second trimester
> 15 mm in the third trimester
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Diagnostic investigations
Renal and bladder ultrasound: as per EAU/ESPU 2025 guidelines, obtain serial ultrasound and subsequent diuretic renography and sometimes voiding cystourethrography for postnatal evaluation.
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Voiding cystourethrography
Diuretic renography
Medical management
Continuous antibiotic prophylaxis: as per EAU/ESPU 2025 guidelines, initiate continuous antibiotic prophylaxis to the subgroup of infants with antenatal hydronephrosis at high risk of developing UTIs, such as uncircumcised infants, as well as in case of hydroureteronephrosis and high-grade hydronephrosis.
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