Correlation between Causes of Prenatal Hydronephrosis and Severity of Anteroposterior Renal Pelvic Dilatation

Introduction & Objective: Prenatal hydronephrosis is increasingly reported because of more extensive application of prenatal sonography in the recent decades. Determination of causes of prenatal hydronephrosis could help in better recognition of natural course of disease and designing proper treatment protocol. On the other hand, severity of renal pelvic dilatation in the first sonography after birth could be related to underlying cause of prenatal hydronephrosis and may be important in diagnostic approach to these patients. This study was performed in order to investigate the causes of prenatal hydronephrosis and it’s relation to severity of renal pelvic dilatation in neonates. Materials & Methods: This is a descriptive cross sectional study of 60 neonates with prenatal hydronephrosis reffered to Hamadan pediatric nephrology clinics of Be’sat and Ekbatan hospitals in Hamadan ,Iran. Case records were thoroughly reviewed for the degree of renal pelvic dilatation in the first postnatal sonography after 3 days of life and the causes of hydronephrosis detected in the follow up workup.The patients were classified according to anteroposterior diameter of renal pelvis to mild dilatation (5–9.9 mm) , moderate (10–14.9 mm) and severe (≥15 mm). Voiding cystoureterography and renal isotope scan (DTPA) were performed in all the patients for diagnosis of vesicoureteral reflux and obstructive uropathy. Results: 44 out of 60 patients(73%) were male and 16(27%) were female. Causes of hydronephrosis were obstructive in 32 patients(53.3%) and non–obstructive in 28 patients(46.7%). There was mild pelvic dilatation in 31 patients,among which 7 (22.6%) had obstructive causes and 24 (77.4%)had non – obstructive causes. Moderate pelvic dilatation was detected in 24 patients,among which 17 (70.8%) had obstructive lesions and 7 (29.2%) had non obstructive causes. Severe dilatation in 5 patients was due to obstructive causes in 4 (80%) and non – obstructive causes in 1 ( 20%) patient. Conclusion: Obstructive lesions were the causes of hydronephrosis in about 50% of the neonates. In this study the most common cause of prenatal hydronephrosis was ureteropelvic junction stenosis and after that idiopathic and vesicoureteral reflux were more common. Severity of renal pelvic dilatation has a direct relationship to the probability of obstructive causes of hydronephrosis (P