Hydronephrosis in children

Hydronephrosis is a common illness in children and consists in the dilatation of the renal collector system. It may be congenital, and in this case is called fetal hydronephrosis, or it can be acquired, which is less frequent. The fetal hydronephrosis may be diagnosed during the intrauterine life through obstetric ultrasound. Mild to moderate dilatations may resolve spontaneously before or after birth. However, larger dilatations can be causes of urinary tract infection, damage to the renal parenchyma, and may require surgical treatment. The main causes of persistent fetal hydronephrosis after birth are ureteropelvic junction stenosis, vesicoureteral reflux, ureterovesical junction stenosis, ureteric duplication associated or not with ureterocele, and posterior urethra valve. In relation to the acquired hydronephrosis, the most common etiology is the angulation of the proximal ureter resulting from an anomalous polar vessel; however, it can also be due to ureterolithiasis, which is uncommon. In these cases, the hydronephrosis is usually diagnosed as the result of propaedeutics of chronic recurrent abdominal pain in older children. The initial conduct in cases of fetal hydronephrosis, shortly after birth, is the use of urinary tract ultrasound to confirm and classify the degree of hydronephrosis. The ultrasound findings will assist to decide if it is necessary to extend the propaedeutics or maintain a waiting conduct. The follow-up by a nephrologist and pediatric-surgeon in the subsequent treatment of these children is