The Incidence and Risk Factors for Urinary Stone Formation in Infants With Prenatal History of Hydronephrosis

Antenatal hydronephrosis (AH) is found in 0. 5-2% of neonates. The aim of the study was to assess the frequency of nephrolithiasis in infants with antenatal hydronephrosis and the risk factors of stone development. In this study، neonates with a history of prenatal hydronephrosis were enrolled during March 2002 until March 2012. Those with any evidence of urinary tract stone were assessed for infectious and metabolic risk factors of stone formation. From 285 studied neonates، 52 (18%) had nephrolithiasis on ultrasound studies and were enrolled into the study. The male to female ratio was 40 to 12. The stone diameter was 3-9 mm; only 1 patiens had bladder stone and all other stones were located in kidneys، more in left kidney. The stone was observed in 10% of patients with vesicoureteral reflux (VUR) and in 20-25% of infants with obstructive urinary disorders. Hypercalciuria was the most common metabolic abnormality. 6 patients (15%) had urinary tract infection (UTI) before detection of stone and 5 (13%) had UTI after diagnosis of nephrolithiasis. The frequency of UTI in patients with VUR and ureteropelvic junction obstruction was 29% and 13%، respectively. There was no history of UTI in patients with posterior urethral valve (PUV) before diagnosis of nephrolithiasis. There were no infectious or metabolic risk factors in 23 patients (58%). Urolithiasis in a common and important complication in infants with prenatal history of hydronephrosis. 64% of the patients had no risk factor other than hydronephrosis for stone formation.