Post Renal Oliguria

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    Bilateral Ureteric Obstruction
        Stones
        Clots
        Sloughed Papilla
        Retroperitoneal fibrosis
        Tumor
    Neurogenic bladder
    Bladder Outlet Obstruction
        Prostatic hypertrophy (needs to be evaluated in every male over 50
          with unexplained renal failure)
        Stones
        Clots
        Urethral stricture
    Blocked foley catheter;