Urine is drained from the kidneys through tubes called ureters. Obstructive uropathy occurs when a one or both ureters becomes blocked; the condition may be acute or chronic.

Acute unilateral obstructive uropathy involves a sudden blockage of one ureter, resulting in a backup of urine and injury to the kidney.

Unilateral obstructive uropathy occurs when urine cannot drain through a ureter because of an obstruction. Urine backs up into the kidney and causes distention of the renal pelvis and calyces (hydronephrosis).

The blockage is most often caused by a kidney stone, although injury or other conditions could cause the disorder.

Risks for unilateral obstructive uropathy include ureteral stones and tumors, kidney stones, and tumors in surrounding structures such as the uterine cervix.

The disorder may result in permanent damage to the kidney and may be a cause of hypertension. It usually does not cause kidney failure because the second kidney continues to function.

Acute unilateral obstructive uropathy occurs in 1 in 1,000 people.

• Flank pain or pain in the side
  • Severe
  • May travel or radiate to the groin, genitals, thigh
  • Periodic and changing intensity over minutes (colicky) or spasmodic
  • On one side
  • Severe enough to require narcotics
  • Radiating to groin
• Nausea or vomiting
• Back pain, may be on only one side
• Abdominal pain, right or left lower quadrant
• Blood in the urine
• Abnormal urine color (tan, cola colored, tea colored)
• High blood pressure that has increased recently (within 2 weeks)
• Urinary tract infection
• Fever
• Urinary frequency
• Urinary urgency
• Foul-smelling urine
• Mental status changes

A history of acute ureteric colic may indicate unilateral obstructive uropathy. Palpation of the abdomen reveals an enlarged or tender kidney. Blood pressure may or may not be elevated. Fever may or may not be present (infection).

The following tests may be conducted:

• Urinalysis may often reveal blood in the urine.
• Urine culture may also reveal urinary tract infection.
• CBC (to look for leukocytosis as a sign of infection)
• Basic metabolic panel (to assess kidney function)

Hydronephrosis and/or obstruction of the ureter may appear on these tests:

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

Treatment focuses on eliminating or minimizing the obstruction.

Antibiotics may be given if there is a urinary tract infection.

Stents or drains placed in the ureter or in the renal pelvis may provide short-term relief of symptoms. Surgery to repair the underlying cause of the obstruction will usually eliminate the problem.

Nephrectomy (removal of the kidney) or nephrotomy (incision into the kidney) may be required if the kidney functions poorly or is severely infected.

The outcome varies. Kidney damage may be permanent. However, if the cause of the obstruction is diagnosed and treated early, the damage may be temporary. If only one kidney is involved, the other kidney usually continues to function adequately and renal insufficiency or renal failure does not occur.

• Permanent failure of the affected kidney (chronic renal failure)
• Chronic unilateral obstructive uropathy
• Chronic or recurrent urinary tract infection
• Hypertension

Call your health care provider if flank pain or other symptoms of acute unilateral obstructive uropathy develop.

Call your health care provider if symptoms worsen during or after treatment, or if new symptoms develop.

If you are prone to kidney stones, drink plenty of water (6 to 8 glasses per day) to reduce the chances of their formation.

Research suggests that a diet low in sodium and oxalate and high in citrate significantly reduces risk of calcium-based kidney stone formation. Consult with a nutritionist for more information on such diets.

Seek medical attention if kidney stones persist or recur to identify the cause and to prevent new stones from forming.