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Hydronephrosis (Urine Blockage) in Newborns and Children

Hydronephrosis (Urine Blockage) in Newborns and Children

Hydronephrosis is a condition of the kidney, occurring when the kidney holds more urine than normal. A prenatal ultrasound may indicate its presence.

What is Hydronephrosis?

This is a general term which refers to increased amounts of urine in the kidney. Hydronephrosis can range from mild (with little to no implication) to severe (requiring surgery). The condition is graded according to severity. Different scales are used. Some scales classify the condition as mild, moderate or severe. Others use a number classification such as the Society of Fetal Urology scale (1-4).

Often hydronephrosis is diagnosed on prenatal ultrasounds. In this situation, a repeat ultrasound is usually performed right after birth and often repeated a few weeks later, as babies are dehydrated during the birthing process and neonatal ultrasounds may underestimate the true amount of hydronephrosis.

What causes Hydronephrosis in Newborns and Children?

Potential causes include:

Variations in normal kidney anatomy
Vesicoureteral reflux (backflow of urine from the bladder to the kidney)
Ureteropelvic Junction Obstruction (Blockage near the kidney)
Ureterovesical Junction Obstruction (Blockage near the bladder)
Urine outflow issues (i.e. posterior urethral valves)
Neurologic causes

What are the symptoms of Hydronephrosis in Newborns and Children?

In the vast majority of children there are no symptoms. A urinary tract infection may be present.

How is Hydronephrosis in Newborns and Children diagnosed?

Ultrasound: This is the mainstay of evaluation as it provides good detail with no radiation. This test may be repeated at varying intervals for further assessment. In many children, this is the only test performed.
Voiding cystourethrogram (VCUG): A catheter is used to fill the child’s bladder with warm liquid containing iodine to make it visible on an x-ray. A video records the x-ray images of the bladder as it is filled and as the child urinates. The video may reveal reflux. This test is only performed when needed, in the appropriate clinical setting.
Nuclear scan: A very small amount of radioactive material is injected into the bloodstream and eventually passes through the kidneys. A camera that captures gamma rays helps determine if the material is properly passing through the urinary tract. This test is generally only performed in select cases, typically with severe hydronephrosis.

How is Hydronephrosis in Newborns and Children treated?

Given there is a large variability in severity and cause of hydronephrosis, each patient is assessed on an individual basis.