Clinical Characteristics, Etiologies, and Management Outcomes of Antenatal Hydronephrosis: A Prospective Observational Study.

Background Hydronephrosis detected during prenatal imaging is among the more frequently encountered fetal renal findings. Although many cases resolve without intervention, some may signify underlying structural abnormalities of the urinary tract that warrant closer evaluation and possible treatment. This study aimed to assess the clinical patterns, causes, and outcomes of postnatal management in neonates and infants diagnosed prenatally with hydronephrosis. Methods A prospective observational study was conducted involving 50 neonates and infants with prenatal evidence of hydronephrosis. Initial postnatal ultrasonography was performed within the first few weeks of life, and additional investigations - such as micturating cystourethrograms and radionuclide scans - were undertaken selectively. Parameters recorded included gender, gestational age at detection, laterality, severity based on ultrasonographic grading, final diagnosis, and management approach. Hydronephrosis was categorized as mild, moderate, or severe. Statistical analysis was used to evaluate the association between the severity and the chosen treatment pathway. Results There was a higher number of male infants in the study group. Most cases were identified during mid-trimester anomaly scans. Involvement was equally distributed between right-sided and bilateral hydronephrosis, with fewer left-sided cases. Over half of the cases were mild, with fewer instances classified as moderate or severe. The most frequent underlying conditions included obstructive and reflux-related pathologies. Conservative observation proved effective in the majority of cases, especially in those with less severe involvement, whereas a minority with severe hydronephrosis required surgical correction. A significant correlation was noted between the degree of hydronephrosis and the need for operative intervention. Conclusion Prenatally identified hydronephrosis includes a range of potential causes that require a structured postnatal diagnostic approach. The severity seen on early imaging is a reliable indicator of likely management needs. Timely evaluation and appropriate monitoring enable effective differentiation between cases that will self-resolve and those requiring surgical care, supporting both clinical decision-making and parental guidance.