Much to the patient's joy ...

Postvoid residual (PVR) measures the amount of urine remaining in the bladder after urination. The patient is asked to urinate immediately before the test, and the residual urine is determined by ultrasound or catheterization. PVR less than 50 mL generally indicates adequate bladder emptying, while measurements of 100 to 200 mL or higher often indicate blockage. The clinical setting may affect the result; therefore, the test is usually repeated.