| An idiopathic condition in which the bladder and bladder outlet are normal but the ureter is dilated to some extent. It may be obstructed, refluxing or unobstructed and not refluxing. Prevalence is unknown, but is the second most common cause of neonatal hydronephrosis. About half of cases are asymptomatic and are discovered on routine antenatal ultrasound. The cause is unknown but it may be due to high fetal urine outflow, changes in the ureter pre and postnatal or transient anatomical obstructions that improve with postnatal development, such as ureteral folds. Not known to be hereditary, but families with more than one affected member have been described. |
