To characterize contemporary resource utilization and medical outcomes for infants with antenatal hydronephrosis and their mothers from a national claims database. We hypothesize that management of isolated hydronephrosis (IHN) varies widely, with decreased imaging following the 2010 Society for Fetal Urology Consensus Statement.

Using MarketScan claims from 2007 to 2013, we identified infants 0-12 months of age with hydronephrosis and linked mothers. Those with urologic diagnoses more specific than hydronephrosis, additional urologic comorbidities, or postnatal surgeries were excluded. Resource utilization including prenatal and postnatal imaging, laboratory studies, hospital admissions, and medical outcomes within the first year was captured. Demographics, maternal characteristics, utilization measures, and outcomes were compared across imaging intensity groups based on number of postnatal ultrasounds received using bivariate analysis.

Among 801,919 mother-child pairs, 8610 infants (1.1%) had hydronephrosis or a related diagnosis. A total of 5876 (68.2%) met inclusion criteria for IHN. Patients underwent a mean 5.3 ± 3.5 prenatal and 2.1 ± 1.3 postnatal ultrasounds before age 1. Imaging practices were unchanged following the Society for Fetal Urology consensus statement.

Antenatal hydronephrosis prevalence in an insured population is consistent with published ranges. Prenatal imaging in IHN is variable and potentially excessive. Future study into the efficacy of evidence-based pathways in reducing excess utilization is warranted.