ICD-9: 591


Hydronephrosis is the distention of the renal pelvis and calyces of a kidney due to pressure from accumulating urine. The pressure impairs, and may eventually interrupt, kidney function. One or both kidneys may be affected.


Hydronephrosis is caused by a urinary tract obstruction. The ureters and renal pelvis dilate proximal to, or behind, the obstruction. This swelling causes the hydronephrosis with resultant destruction of functional tissue. In children, the obstruction is usually the result of some congenital defect in urinary tract structure. In adults, the obstruction is more often acquired, resulting from blockage by neoplasms or uroliths, commonly called kidney stones or renal calculi. Urinary tract obstruction in men may be produced by benign or malignant enlargement of the prostate. Women may experience urinary tract obstruction as a complication of pregnancy. Underlying disorders such as neurogenic bladder also may allow urine to accumulate to the extent that it produces hydronephrosis.

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Signs and Symptoms

The signs and symptoms depend on the site of obstruction, the cause, and the rapidity with which the condition developed. If the obstruction is above the opening of the bladder, only one kidney may be affected and the person may be asymptomatic for a prolonged period (“silent” hydronephrosis). Symptoms may be severe, however, especially if both kidneys are affected. The person often complains of intense flank pain, nausea, vomiting, dysuria, oliguria or anuria, and hematuria. Clients may also complain of unexplained pruritus.

Diagnostic Procedures

Palpation and percussion of the abdomen may reveal distention of the kidney or urinary bladder.

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A history of changes in urinary volume, difficulty in voiding, and pain may be found. Ultrasound may be ordered to visualize obstructions. A noncontrast spiral CT scan may be ordered to further define the site of obstruction. Urinalysis may reveal hematuria, pus, and bacteria and may be helpful in determining the extent of any impairment of renal function.


Treatment goals include draining excess urine from the kidney, removing any obstruction, preventing complications, and treating underlying disorders. Catheterization may be necessary for the immediate relief of urinary pressure. Analgesics may be prescribed. Antibiotics are required to treat infection. Surgery is sometimes required to dilate a ureteral stricture.

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Complementary Therapy

No significant complementary therapy is indicated.

Client communication

Encourage regular medical chec kups, and explain symptoms of hydronephrosis so that the client can report them to the primary care provider as necessary.


The prognosis is variable depending on whether one or both kidneys are affected, whether the obstruction can be removed, and whether permanent renal damage has occurred.


There are no specific preventative measures. Prompt treatment of conditions that can cause hydronephrosis is important.