Men with bladder outlet obstruction (BOO) defined by invasive pressure flow studies (PFS) have success rates following TURP that are 15–29% higher than those without PFS. Invasive PFS are not commonly performed because of patient discomfort, infection risk, and cost associated with the need for skilled staff and specialised equipment. 65–75% of men achieve satisfactory symptomatic benefit following surgery. The CT3000 improves outcome prediction for men considering surgery to 87%. **GRAPHIC**