Blockages usually have to be corrected. Reflux Vesicoureteral reflux occurs when the valve between the bladder and the ureter is incompetent permitting urine to backflow to the kidney when the bladder fills or empties. Only a minority of refluxers require surgical correction either because of failure to outgrow reflux or because of breakthrough urinary tract infections. These may show up on fetal ultrasound. Occasionally patients with duplication have a ureterocele which is a balloon-like obstruction at the end of one of the duplex tubes.
Multicystic kidney is a non-functional cystic kidney.
In nearly all instances of antenatal hydronephrosis, ultrasound surveillance is all that is necessary. In the rare fetus with severe obstruction of both kidneys and insufficient amniotic fluid, drainage of the kidneys or bladder by tube or operation has been performed experimentally. While these procedures are technically possible, the outcome of the babies has not, to date, been improved. These babies are likely to have very abnormal kidneys that do not function well and also may have inadequate lung development. For most cases of antenatal hydronephrosis pregnancy is not affected and delivery can be performed normally.