Clinical Implications of Prenatal Ultrasonographic Detection of Horseshoe Kidney: Association with Postnatal Outcomes

Objectives: Prenatal diagnosis of horseshoe kidney (HSK), a common congenital renal fusion anomaly of the upper urinary tract, remains challenging. Most cases are identified only after birth; however, the clinical significance of prenatal detection and its impact on postnatal outcomes remains unknown. Methods: We investigated infants with postnatally confirmed HSK born at a tertiary referral center between January 2009 and August 2025. Prenatal ultrasonographic findings and postnatal outcomes were reviewed. Patients were classified into three groups according to prenatal detection status: missed HSK (group 1), prenatally detected renal abnormalities without recognition of HSK (group 2), and prenatally identified HSK (group 3). Perinatal outcomes, postnatal urological complications, renal function, and associated anomalies were compared. Results: Overall, 29 infants were included in this study. Perinatal outcomes, including gestational age at delivery, birth weight, preterm birth, Apgar scores, need for ventilatory support, and neonatal sex, did not differ significantly among the groups. Hydronephrosis and renal scarring were more frequently observed in group 2 than in the other groups. Other urological outcomes, renal function parameters, and mortality rates were comparable between the groups. Conclusions: This adds to the limited longitudinal evidence linking the prenatal to postnatal period and evaluating the full spectrum of prenatal detection in HSK, as well as its association with postnatal outcomes. Postnatal outcomes are closely associated with the presence of renal abnormalities. Therefore, prenatal imaging is more appropriate for identifying associated renal abnormalities than for establishing a definitive diagnosis of HSK.