It is helpful to categorize the mechanism as prerenal (eg, resulting from decreased or abnormal renal perfusion), renal (eg, resulting from intrinsic renal disease), or postrenal (eg, disease of the urinary collecting system distal to the renal parenchyma). Prerenal and postrenal causes are often suggested by the history and physical examination. Additionally, it is be helpful to determine the presence and extent of acute kidney injury (AKI) that frequently accompanies oliguria and anuria.
Prerenal causes include hypovolemia, sepsis, and heart failure.
Renal causes include tubular, glomerular, vascular, or interstitial disease.
Supravesical obstruction rarely causes oliguria or anuria, because bilateral disease is required to reduce decreased urine flow. There are two types of supravesical obstruction: (1) ureteral obstruction (usually tumor) and (2) ureteropelvic or ureterovesical obstruction.
Intravesical or Infravesical Obstruction
Intravesical or infravesical obstruction is more common than supravesical obstruction and may be from many causes (Table 39–1).
Table 39–1. Diagnostic Clues to the Cause of Bladder Outlet Obstruction. |Favorite Table|Download (.pdf)
Table 39–1. Diagnostic Clues to the Cause of Bladder Outlet Obstruction.
|Cause||Frequency of Occurrence||Results of History and Physical Examination||Laboratory Tests and Other Studies|
|Prostatic hypertrophy||Common||Gradually increasing difficulty in voiding, often with abrupt worsening. Enlarged prostate on rectal examination is common||Urethral catheterization may be difficult.|
|Urethral strictures or valves||Uncommon||Often previous attacks of urethritis or urethral trauma. Onset may be gradual or abrupt||Urethral catheterization often difficult. Urethrogram or urethroscopy is diagnostic|
|Bladder stones or tumor||Uncommon||Hematuria is common. Obstruction may be intermittent||Urethral catheter is passed without difficulty. Cystogram or cystoscopy is diagnostic|
|Neuropathic bladder||Very common||Onset may be gradual and painless or abrupt and painful. Look for associated neurologic abnormalities (sacral dermatomal hypesthesia, poor rectal sphincter tone, neuralgic pain)||Urethral catheter passed without difficulty. Cystometrogram is diagnostic|
|Traumatic urethral injury||Uncommon||Male; history of trauma, prostatic dislocation, urethral bleeding||Do not pass catheter. Retrograde urethrogram and percutaneous cystogram are diagnostic|
Differentiate between reduced urine output (with normal or nearly normal voiding patterns) and oliguria associated with difficult in voiding, feeling of incomplete voiding, and diminished urinary stream. The latter findings suggest obstruction.
Associated Medical Conditions
Ask about coexisting cardiac, pulmonary, renal, or other underlying disease that might contribute to renal or prerenal oliguria.
The patient's medications might cause problems with urination or be nephrotoxic. Anticholinergics and sympathomimetics are most often the culprits of urinary retention.