Hydronephrosis

Stretching or dilation of the urinary tract may occur because of a blockage to the flow of urine, which causes increased pressure “up stream,” and leads to urine building up above the point of blockage.

Hydronephrosis can also occur due to an abnormal connection between the ureter and bladder that allows urine to flow backward toward the kidney when the bladder contracts to empty. This condition is known as reflux.

Sometimes hydronephrosis can be caused by a blockage that has cleared and left the urinary system stretched but not under any pressure.

How is Hydronephrosis Diagnosed?

Medical advances in prenatal ultrasound examinations have helped identify large numbers of infants with urinary dilation or stretching prior to birth. In diagnosing hydronephrosis, Nemours urologists may recommend a voiding cystourethrogram (VCUG) and a renal (kidney) scan.

The VCUG tells us if the “one-way” valve in the bladder is functioning, while the renal scan reveals how well the kidneys are functioning and assesses how fast the urine drains from the kidney into the bladder to see if a blockage exists. These studies help determine if surgical repair or immediate treatment is needed since hydronephrosis can lead to urinary tract infections (UTIs) and sometimes permanent kidney damage.