Also known as: hydronephrosis of one kidney.

What is hydronephrosis?

The urinary tract has 4 parts: two kidneys, the two ureters through which urine flows to the bladder, the bladder and the urethra the short tube out of the bladder through which urine is passed out of the body.

Hydronephrosis is a condition where one or both kidneys swell either because of a blockage/obstruction of urine flow or because of reverse urine flow from the bladder (reflux).

Hydronephrosis may be mild, moderate or severe.

What causes hydronephrosis?

Hydronephrosis is almost always due to an obstruction to the flow of urine (anywhere along its pathway outwards, like from narrowing where the kidney and ureter join-ureteropelvic junction obstruction (UPJ), ureterovesical junction obstruction (UVJ), posterior urethral valves (PUV), OR because of reflux of urine from the bladder backwards up the ureters towards the kidneys (VUR). Other rarer causes exist and often particularly if diagnosed during pregnancy, no cause is found.

What are the symptoms of hydronephrosis?

Many children with mild hydronephrosis have no symptoms. In severe cases acute flank kidney pain, fever, urinary bleeding, and symptoms of a urinary tract infection are not uncommon.

What are hydronephrosis care options?

Treatment depends on when the diagnosis is made (pre or postnatal), it’s severity and the underlying cause and may include antibiotics and/or a surgical procedure as deemed necessary.

Reviewed by: Jack Wolfsdorf, MD, FAAP

This page was last updated on: April 11, 2023 06:25 PM

Pediatric Urology

The Division of Pediatric Urology and Urologic Surgery at Nicklaus Children’s Hospital specializes in the treatment and diagnosis of urological conditions.

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