What initial tests assess suspected bladder outlet obstruction in men with LUTS?

• A. Cystoscopy
• B. Uroflowmetry and post-void residual measurement; bladder scan
• C. Urinalysis and culture
• D. Serum PSA

Answer: (B)

The key idea is to use noninvasive tests that quantify how well the bladder and outflow are functioning during and after voiding. Uroflowmetry measures the urine flow rate and the pattern of the stream. A reduced maximum flow rate and an abnormal flow pattern (such as a plateau or interrupted stream) raise suspicion for bladder outlet obstruction or impaired detrusor function. To know whether the bladder is emptying completely, post-void residual measurement is used, typically with a bladder scan ultrasound. If a meaningful amount of urine remains after voiding, it supports the likelihood of incomplete emptying from obstruction or detrusor weakness. Taken together, these tests provide objective, initial evidence of obstruction and help guide next steps.

Other tests serve different purposes and are not first-line for assessing suspected obstruction: urinalysis and culture screen for infection or stones; serum PSA screens for cancer risk; cystoscopy directly visualizes the bladder and urethra but is invasive and not an initial test.