Hydronephrosis

Hydronephrosis

Signs and Symptoms
Diagnosis
Treatment

Signs and Symptoms

Hydronephrosis is when a kidney becomes distended or swollen with urine due to a blocked or narrowed ureter. Ureters are the tubes that drain urine from the kidneys into the bladder. Hydronephrosis occurs when urine is unable to drain into the bladder. The three main conditions that cause hydronephrosis are:

• Vesicoureteral Reflux -- This is the abnormal backflow of urine from the bladder into the ureter and up to the kidney. This may be caused by an abnormality in how the ureter connects with the bladder or problems caused by nerve problems or dysfunctional voiding.

• Non-Obstructive Hydronephrosis Swelling in the kidney that has no effect on kidney function.

• Ureteropelvic Junction (UPJ) Obstruction -- In this condition, the ureter is "kinked" or narrow where it joins the kidney.

Other conditions that can cause hydronephrosis in children include:

• Ureterocele -- The urine swells the portion of the ureter closest to the bladder because the ureter opening is too small for the free flow of urine into the bladder.

• Posterior Urethral Valves -- This is when the normal valve in the urethra, the tube that drains urine from the bladder to outside the body, is too narrow to allow free urine flow. This condition occurs only in boys.

• Ureterovesical Junction (UVJ) Obstruction -- This occurs when the valve where the ureter connects with the bladder is absent or nonfunctional. The pressure generated by the bladder emptying will force urine backward into the ureter and kidney, causing dilation without a mechanical obstruction.

• Megaureter -- This occurs when one or both of the ureters are too wide.

• Multicystic Dysplastic Kidney -- A kidney does not function because there is cystic tissue instead of normal kidney tissue.

• Ectopic Ureter -- This is a ureter that either bypasses the bladder completely or connects to the bladder in the wrong place.

• Neurogenic Bladder -- The normal nerve pathways associated with urination don't function properly.

• Nonneurogenic Neurogenic Bladder -- This is an emotionally influenced form of urinary retention.

Symptoms

Children with mild hydronephrosis usually don't have symptoms. Even children with moderate hydronephrosis may not exhibit symptoms. Researchers suggest that the kidney compensates for hydronephrosis to maintain normal function. However, severe hydronephrosis can damage the kidney resulting in infections, pain and bleeding. Symptoms of urinary infection can include painful urination, cloudy urine, back pain and fever. Nephrosis, or kidney disease, also may result in difficulty passing urine, either by being irregular or uncontrolled.

Reviewed by health care specialists at UCSF Children's Hospital.
Last updated May 8, 2007