Hydronephrosis

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.

Diagnosis

Hydronephrosis usually is diagnosed in one of two ways.

1. An ultrasound during pregnancy may reveal a fetus with dilated kidneys. This occurs in 1 per 100 pregnancies.

2. An ultrasound done as part of an evaluation for another medical problem, such as a urinary tract infection or incontinence, may reveal hydronephrosis.

Once hydronephrosis is noted, whether during pregnancy or later, additional tests often are required to find out the severity. These tests are important because early diagnosis and treatment of a potential abnormality can prevent urinary tract infections and permanent kidney damage or scarring.

Tests include:

• Voiding Cystourethrogram (VCUG) -- A VCUG gives us important information about the shape and size of the bladder, the bladder neck or opening and the tubes that drain the urine from the kidneys into the bladder called ureters. It allows us to diagnose reflux -- the abnormal back-flow of urine from the bladder into the ureter and up to the kidney. It also gives us anatomic information about the urethra, the tube that takes urine from the bladder outside the body, to make sure there's no blockage, a condition called posterior urethral valves.

• Kidney (Renal) Scan -- A kidney scan may be performed depending on the history of urinary tract infections, result of VCUG and the severity of the hydronephrosis. It is used to show the function and drainage of the kidneys. A kidney scan also can show if there is kidney damage and scarring from a previous urinary tract infection or long-standing hydronephrosis. Two types of renal scans are typically performed depending on the diagnosis.

  • Lasix Renogram or MAG-III diuretic renogram: This tests for significant blockage in the urinary tract.
  • DMSA (dimercaptosuccinic acid) scan: This tests for scarring or damage to the renal tissue, which is more common in patients with vesico-ureteral reflux.

If your newborn child had hydronephrosis -- kidney, ureter or bladder dilation -- noted on a pre-natal ultrasound, another ultrasound should be conducted one to three days after birth. It is normal for a newborn to be dehydrated and produce less urine on the first day of life. It may falsely appear that your baby no longer has hydronephrosis. Certain conditions seen on the ultrasound such as severe hydronephrosis in both kidneys or a dilated bladder may warrant more tests. A VCUG will be performed within the next several weeks of life.

Hydronephrosis is graded on a scale from zero to four, with one the mildest form and four the most severe. The degree of hydronephrosis is used to help decide the treatment for the underlying cause of the hydronephrosis. More severe grades of hydronephrosis require more extensive tests. For example, grade III and IV hydronephrosis (not due to vesicoureteral reflux) typically require a renal scan.

Treatment

If your child is not on antibiotics, he or she will receive a prescription for a low-dose, daily antibiotic. The types of antibiotics are very specific for the urinary tract and have very few, if any, side effects. The type of antibiotics your child will receive depends on your child's age, weight and allergies. The goal of antibiotics is to prevent kidney infections that may occur as a result of the hydronephrosis. Once the special X-ray tests have been completed, we can estimate the total time of antibiotic treatment.

Typically, non-obstructive hydronephrosis and grade one to three hydronephrosis don't need surgery and resolve over time. The need for surgery depends on the severity of the hydronephrosis and is different for each child. Children diagnosed with dilation from ureterovesical junction abnormalities called megaureters rarely if ever need surgical repair. Children with grade four hydronephrosis, the most severe, are the most likely to require surgery to prevent renal damage and recurrent infection. The surgery to correct hydronephrosis is called pyeloplasty.