Which finding would indicate bladder outlet obstruction on urodynamics?

• A. Low detrusor pressure with high flow
• B. High detrusor pressure with low flow
• C. Normal detrusor pressure with normal flow
• D. High detrusor pressure with high flow

Answer: (B)

The key idea is that bladder outlet obstruction causes the bladder to work harder to overcome resistance. On pressure–flow urodynamics, this shows up as a high detrusor (bladder) pressure during voiding combined with a low urine flow rate. The detrusor must generate extra pressure to push urine through the narrowed outlet, but the obstruction keeps the flow diminished. That pattern—high detrusor pressure with low flow—is the strongest indicator of obstruction.

In contrast, normal or low detrusor pressure with normal or high flow suggests no obstruction, and high detrusor pressure with high flow is not typical for true outlet obstruction because the outlet isn’t resisting significantly enough to limit flow.