Objective: To share our nine-year experience with antenatal hydronephrosis (AH), which is usually transient but may be associated with congenital anomalies of the kidney and urinary tract (CAKUT) and can therefore be worrisome for families.

Material and Methods: 230 patients with AH who presented to general pediatrics outpatients between January 2005 and December 2013 were evaluated retrospectively. Each patient’s weight, height, blood pressure values and laboratory, ultrasound, dimercaptosuccinic acid, diethylenetriamine pentaacetic acid, and voiding cystourethrography results were recorded.

Results: 91.8% of the patients had unilateral AH; 200 patients (87.0%) had left kidney AH, 11 (4.8%) had right kidney AH, and 19 (8.3%) had bilateral AH. The degree of hydronephrosis was mild in 175 patients (76.1%), moderate in 38 patients (16.5%), and severe in 17 patients (7.4%). Non-obstructive hydronephrosis was detected in 195 patients (84.8%), vesicoureteral reflux was detected in 19 patients (8.2%), pelvi-ureteric junction obstruction was detected in 14 patients (6.1%), and posterior urethral valve was detected in 2 patients (0.9%). An increased risk of urinary tract pathology was observed with increasing degrees of hydronephrosis (p<0.001). The detection rate of urinary tract pathology was significantly higher in the patients with bilateral AH compared with unilateral AH (p=0.008). The spontaneous recovery rates for the non-obstructive AH patients with mild and moderate dilatation were 96.4% and 78.6%, respectively

Keywords: Antenatal diagnosis, Infant, CAKUT, Hydronephrosis, Spontaneous remission