Obstructive uropathy involves a blockage of the flow of urine, causing it to back up and injure one or both kidneys.

Obstructive uropathy occurs when urine cannot drain through a ureter (a tube that carries urine from the kidneys to the bladder). Urine backs up into the kidney and causes it to become swollen (hydronephrosis).

Obstructive uropathy is grouped according to whether it affects one or both kidneys and whether it occurs suddenly or is long term:

• Chronic unilateral obstructive uropathy - Long-term uropathy that affects one kidney
• Chronic bilateral obstructive uropathy - Long-term uropathy that affects both kidneys
• Acute unilateral obstructive uropathy - Sudden uropathy that affects one kidney
• Acute bilateral obstructive uropathy -Sudden uropathy that affects both kidneys

Common causes of obstructive uropathy include the following:

• Urinary tract stones
  • Ureteral stones
  • Bladder stones
• Urinary tract tumors
• Retroperitoneal fibrosis
• Benign prostatic hyperplasia (enlarged prostate)
• Tumors of nearby organs
• Colon cancer
• Cervical cancer
• Uterine cancer
• Any cancer that spreads
• Idiopathic hydronephrosis of pregnancy

Symptoms associated with obstructive uropathy vary depending on whether the obstruction is acute or chronic, whether it is unilateral or bilateral, whether it is complete or partial, and what caused it. Common symptoms of obstructive uropathy include the following:

• Flank pain
  • Bilateral or unilateral
  • Colicky or severe
• Urinary tract infection
• Fever
• Difficulty or pain while urinating
• Nausea or vomiting
• Renal failure
• Weight gain or swelling (edema)
• Decreased urine output
• Blood in the urine

The diagnosis of obstructive uropathy is made on imaging studies. Common radiographic studies used to diagnose obstructive uropathy include:

• Abdominal ultrasound
• Abdominal CT scan
• Intravenous pyelogram (IVP)
• Voiding cystourethrogram
• Renal nuclear scan

Stents or drains placed in the ureter or in the renal pelvis may provide short-term relief of symptoms. Nephrostomy tubes, which drain urine from the kidneys through the back, may be used to bypass the obstruction. A Foley catheter, inserted through the urethra, may also be helpful.

Although temporary relief from the obstruction can be achieved without surgery, the cause of the obstruction must be removed and the urinary system repaired. Long-term relief from obstructive uropathy requires surgery.

If acute obstruction is rapidly diagnosed and repaired, kidney damage is minimal or reversible -- regardless of being unilateral or bilateral. If chronic unilateral obstruction is not relieved promptly there could be permanent damage to the kidney. Chronic unilateral obstruction usually does not cause kidney insufficiency or failure because most patients have normal function from the other kidney.

Chronic bilateral obstruction may lead to kidney insufficiency or failure because both kidneys may become damaged and fail to function even after obstruction is repaired.

Obstructive uropathy can cause permanent and severe damage to the kidneys, resulting in renal failure. Obstructive uropathy caused by bladder outlet obstruction can lead to permanent and severe damage to the bladder, resulting in problems such as incontinence, urinary retention.

Contact your health care provider if you have symptoms of obstructive uropathy or believe that you may be suffering from this condition.

Obstructive uropathy can be prevented by preventing the disorders that cause it.

Walsh PC. Campbell's Urology. 8th ed. St. Louis, Mo: WB Saunders; 2002:412. 

Goldman L, Ausiello D. Cecil Textbook of Medicine, 22nd ed. Philadelphia, Pa: WB Saunders; 2004:741-742.