Hydronephrosis

An abnormal dilation of the renal pelvis and the calyces of one or both kidneys, hydronephrosis is caused by an obstruction of urine flow in the genitourinary tract. Although partial obstruction and hydronephrosis may not produce symptoms initially, the pressure built up behind the area of obstruction eventually results in symptomatic renal dysfunction.

Causes

Almost any type of obstructive uropathy can result in hydronephrosis. The most common causes are benign prostatic hyperplasia, urethral strictures, and calculi; less common causes include strictures or stenosis of the ureter or bladder outlet, congenital abnormalities, abdominal tumors, blood clots, neurogenic bladder, and tumors of the ureter and bladder.

Sites of obstruction

If obstruction is in the urethra or bladder, hydronephrosis is usually bilateral; if obstruction is in a ureter, it's usually unilateral. Obstructions distal to the bladder cause the bladder to dilate and act as a buffer zone, delaying hydronephrosis. Total obstruction of urine flow with dilation of the collecting system ultimately causes complete cortical atrophy and cessation of glomerular filtration.

Signs and symptoms

Clinical features of hydronephrosis vary with the cause of the obstruction. In some patients, hydronephrosis produces no symptoms or only mild pain and slightly decreased urine flow; in others, it may produce severe, colicky renal pain or dull flank pain that may radiate to the groin and gross urinary abnormalities, such as hematuria, pyuria, dysuria, alternating oliguria and polyuria, and complete anuria.

Other symptoms of hydronephrosis include nausea, vomiting, abdominal fullness, pain on urination, dribbling, and hesitancy. Unilateral obstruction may cause pain on only one side, usually in the flank area.

Complications

The most common complication of an obstructed kidney is infection (pyelonephritis) due to stasis that exacerbates renal damage and may create a life-threatening crisis. Paralytic ileus frequently accompanies acute obstructive uropathy.

Diagnosis

Although the patient's clinical features may suggest hydronephrosis, excretory urography, retrograde pyelography, renal ultrasonography, and renal function studies are necessary to confirm it.

Treatment

The goals of treatment are to preserve renal function and prevent infection through surgical removal of the obstruction, such as dilation for stricture of the urethra and prostatectomy for benign prostatic hyperplasia.

If renal function has already been affected, therapy may include a diet low in protein, sodium, and potassium. This diet is designed to stop the progression of renal failure before surgery.

Inoperable obstructions may require decompression and drainage of the kidney, using a nephrostomy tube placed temporarily or permanently in the renal pelvis. Concurrent infection requires appropriate antibiotic therapy.

Alternative treatment

Catheters or other urinary diversions may be better for weak or ill patients who cannot tolerate more extensive procedures. There is support using botanical medicine that can help the patient using a catheter avoid infections. Consultation with a trained health care practitioner is necessary.

Prevention

Kidney stones can be prevented by dietary changes and medication. Prompt evaluation of infections and urinary complaints will usually detect problems early enough to prevent long-term complications.