Prenatal Ultrasound Diagnosis of Fetal Renal Malformations: A Case Series

Background: Congenital anomalies of the kidney and urinary tract (CAKUT) represent a diverse group of conditions, ranging from mild findings to serious disorders with sig-nificant health implications. These anomalies arise when the normal development of the kidneys or urinary tract is interrupted—affecting the renal collecting system, the kidney tissue itself, or the migration of the kidneys to their usual position. Prenatal ultrasonog-raphy has become an essential tool for detecting these anomalies before birth, offering valuable time for planning care and support. Objective: To describe the prenatal ultra-sound characteristics of fetal renal malformations and evaluate how often these findings are confirmed after birth. Methods: We conducted a descriptive study at Hospital de Gineco-Pediatría No. 7 in Cancún, Quintana Roo, between 2022 and 2024. We reviewed prenatal ultrasound reports and clinical records to collect information on maternal de-mographics, clinical history, risk factors, and ultrasound findings. Only cases in which CAKUT was confirmed after birth were included. This was an observational study with no risk to participants. Results: We identified 15 fetuses with confirmed CAKUT, totaling 16 malformations because one newborn had two separate anomalies. Slightly more than half (58.8%) of the affected fetuses were male, and the median gestational age at birth was 38 weeks. Mothers had a mean age of 32.46 years. After delivery, 68.8% of the newborns were male, with an average birth weight of 3,039.2 g (± 601.08). Anomalies of the renal collecting system were most common (63.0%, n=10). Among these, congenital hydro-nephrosis was the leading diagnosis, seen in 4 cases (25.2%). Renal ectasia, considered a parenchymal anomaly, was also found in 4 cases (5.2%).Conclusion: Prenatal ultrasound is a highly valuable tool for identifying fetal kidney and urinary tract anomalies before birth—especially those involving the collecting system. Our findings reinforce the known association between male sex and CAKUT and emphasize the critical role of routine prenatal screening. Early detection not only aids in confirming the diagnosis after birth but also enables the development of structured, individualized care plans for newborns, improving their chances for a healthier future.