Bilateral hydronephrosis

Alternative names
Hydronephrosis - bilateral


Bilateral hydronephrosis is the distention of the pelvis and calyces of both kidneys. (See also unilateral hydronephrosis.)

Causes, incidence, and risk factors

Bilateral hydronephrosis develops when the pelvis and calyces (the urine collecting structures of the kidneys) of both kidneys become distended because urine is unable to drain from the kidney down the ureters into the bladder. (Bilateral means both sides.)

Hydronephrosis is therefore not itself a separate disease, but rather a physical manifestation of the disease process that keeps urine from draining out of the kidneys, ureters, and bladder. The symptoms, treatment, and expected outcome are those of the associated diseases.

Disorders associated with hydronephrosis include:

  • acute bilateral obstructive uropathy  
  • chronic bilateral obstructive uropathy  
  • vesicoureteric reflux  
  • uteropelvic junction obstruction  
  • posterior ureteral valves  
  • neurogenic bladder  
  • bladder outlet obstruction  
  • prune belly syndrome

Advances in fetal ultrasound have given specialists the ability to diagnose obstructive uropathy (problems caused by the blockage of the urinary system) in the fetus before birth. Unilateral (one side only) or bilateral (both sides) obstruction of the urinary tract can be diagnosed by fetal ultrasound. Fetal conditions such as uteropelvic junction obstruction, posterior ureteral valves, and prune belly syndrome can be diagnosed while the fetus is in the uterus.

Newborn infants who have been previously diagnosed with obstruction while still in the uterus can receive prompt surgical correction of the defects, often with good results.

Experimental surgery on the fetus while in the uterus, which can relieve the obstruction or decrease the pressure on the kidney in the fetus, is presently being studied. Future techniques can be expected to salvage better kidney function than the good results that are presently expected.


Signs of hydronephrosis is generally observed during routine fetal ultrasound studies done during routine pregnancies and as such there are no symptoms in the fetus.

In the newborn, any diagnosed urinary tract infection is reason to suspect some type of obstructive problem in the kidney. In the older child, repeat urinary tract infections are cause for evaluation of possible obstruction.

Unfortunately, with the exception of an increased number of urinary tract infections, obstruction of the urinary tract is often without symptoms.

Signs and tests
Bilateral hydronephrosis may be apparent on:

  • IVP  
  • Renal scan  
  • Ultrasound of the abdomen or kidneys  
  • CT scan of the abdomen or kidneys


Treating bilateral hydronephrosis includes two facets: relieving obstruction and treating the underlying disorder responcible for the hydronephrosis. Bilateral hydronephrosis results usually (but not always) due to a blockage below the level of the bladder. Thus, placing a foley catheter may relieve the obstruction.

Draining the bladder or relieving pressure through percutaneous nephrostomy tubes are other options. Once the obstruction is dealt with, then attention must be paid to treat the underlying cause (such as an enlarged prostate).

Expectations (prognosis)

If an obstruction is detected in a fetus, surgery shortly after birth will optimize the function of the kidneys. Early discovery and intervention in any type of obstructive process will improve the outcome.

Renal insufficiency or failure may develop as a complication of many of the disorders associated with hydronephrosis.

Calling your health care provider
This disorder is usually discovered by the health care provider.

A fetal ultrasound can reveal an obstruction of the urinary tract and allow for early surgery with better outcomes in the newborn. Other causes of obstruction, such as kidney stones, can be diagnosed early if individuals recognize early warning signs of obstruction and kidney disease.

Johns Hopkins patient information

Last revised: December 3, 2012
by Gevorg A. Poghosian, Ph.D.

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