What is it?

The kidneys filter our blood and get rid of wastes by making urine. Urine leaves the kidneys and passes down into the bladder through tubes called ureters. If the connection between the kidney’s outflow (renal pelvis) and the start of the ureter narrows too abruptly, the urine flow is impeded and the kidney cannot drain well. The urine backs up and we see hydronephrosis (swelling) on an ultrasound. The narrowing is usually on the inside of the tubes but can also be caused by a nearby blood vessel pressing on the outflow. It can cause pain, kidney stones and infections. Left untreated over many years, it can cause the kidney to lose all its function.

What might I notice if my child has it?

Babies are often diagnosed with no symptoms at all but rather the presence of increasing hydronephrosis on ultrasound. There are more invasive tests (such as a Lasix renogram) that specifically evaluate kidney drainage and function. Older children may complain of episodic back/flank/abdominal pain associated with nausea and vomiting.

What are the treatment options?

Most children require surgery (Pyeloplasty) to remove the narrowed segment, improve drainage and prevent further damage to the kidney.