Clinical outcome and follow-up of prenatal hydronephrosis.

Hydronephrosis is probably the most common congenital abnormality detected prenatally by ultrasonography This study was performed to determine the cause and outcome of prenatal hydronephrosis in our hospital. A total of 45 infants, with 57 prenatally hydronephrotic renal units, were enrolled into this study. For the purpose of this study, the degree of hydronephrosis was defined as mild, moderate or severe. Postnatal ultrasonography was performed as soon as possible in those with bilateral hyronephrosis and 3-7 days after birth in those with unilateral hydronephrosis. Voiding cystourethrogram was performed in 6-8 weeks time. In the absence of vesicoureteral reflux (VUR), diethylenetriamene penta acetate scan was performed to exclude obstructive uropathy. There were 29 males and 16 females (male:female ratio 1.8:1), and unilateral and bilateral hydronephrosis were seen in 33 (73%) and 12 (27%) of the cases, respectively. Hydronephrosis was caused by ureteropelvic junction obstruction (UPJO) in 20 (44.5%), VUR in 10 (22.2%), ureterovesical junction obstruction in four (8.9 %), posteriorurethral valves in four (8.9 %), UPJO with VUR in two (4.4%) and non-VUR non-obstructive in one (2.2%). During follow-up, 16 patients (35.5%) required operative intervention while seven (15.5%) improved spontaneously. Fetal hydronephrosis needs close follow-up during both ante-natal and postnatal periods. In this study, the most common cause for hydronephrosis were UPJO and VUR. Also seen in this study is the noteworthy point that mild fetal hydronephrosis is relatively benign and does not require surgical intervention in most cases and surgery should be performed only if there is renal function compromise. Prenatal consultation with a pediatric nephrologist and urologist is useful in decreasing parental anxiety and facilitating postnatal management.