Description, Causes and Risk Factors:
Obstructive uropathy is a condition in which the flow of urine is blocked, causing it to back up and injure one or both kidneys. Many conditions can cause obstructive uropathy, which may be acute or chronic, partial or complete, and unilateral or bilateral. The most common causes differ by age:
Young adults: Calculi.
Older adults: BPH or prostate cancer, retroperitoneal or pelvic tumors, and calculi.
Children: Anatomic abnormalities (including urethral valves or stricture and stenosis at the ureterovesical or ureteropelvic junction).
Obstruction may occur at any level, from the renal tubules (casts, crystals) to the external urethral meatus. roximal to the obstruction, effects may include increased intraluminal pressure, urinary stasis, UTI, or calculus formation (which may also cause obstruction). Obstruction is much more common in males (usually due to BPH), but acquired and congenital urethral strictures and meatal stenosis occur in both males and females. In females, urethral obstruction may occur secondary to a tumor or as a result of stricture formation after radiation therapy, surgery, or urologic instrumentation (usually repeated dilation).
No data are available on the incidence and prevalence of urinary obstruction in unselected populations. In large surveys of elderly men a prevalence of 20-35% has been estimated for symptoms of urinary obstruction. Post-mortem examinations have found hydronephrosis in 3.8% of adults and 2.0% of children. Obstructive uropathy associated with congenital anomalies of the urinary tract accounts for 30-50% of all end stage renal disease cases in children. In women, obstruction is more likely to occur at a younger age as a result of pregnancy or uterine cancer.
The prognosis depends on the cause, site, duration, and degree of kidney demage and renal decompensation. In general, relief of obstruction leads to improvement in kidneys,especially those destroyed by inflammatory scarring.
The signs and symptoms of urinary obstruction dependon the parameters already discussed. Thedifferentiation between acute or chronic obstruction is purely clinical. Chronic obstruction is usuallyasymptomatic. When the obstruction is bilateral,patients may present with uremia. Most acuteobstructive uropathies, on the other hand, areassociated with significant pain or the abrupt diminutionof urine flow. The severity of the pain depends on therate of distention more than the amount of dilation ofthe renal capsule.Patients describe a colic pain inthe flank that increases with consumption of largeamounts of fluid or following diuretic administration.Anuria frequently occurs in acute obstruction and lessfrequently in chronic situations. Sometimes, inunilateral obstruction or partial bilateral obstruction, thepatient may notice significant increases in urinaryoutput independent of fluid intake related to thedamaged kidney's inability to concentrate urine.
The diagnosis of obstructive uropathy is made on imaging studies. Common radiographic studies used to diagnose obstructive uropathy may include:
CT scan of the belly area (abdomen) or pelvis.
Intravenous pyelogram (IVP).
Voiding cystourethrogram (VCUG).
Renal nuclear scan.
Duplex Doppler ultrasonography.
Antegrade or retrograde pyelography.
Ultrasound of the belly area (abdomen) or pelvis.
Stents or drains placed in the ureter or in a part of the kidney called 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, placed through the urethra into the bladder, may also be helpful.
Although short-term 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.
NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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