Can intravesical prostatic protrusion predict bladder outlet obstruction even in men with good flow?

OBJECTIVE: Men with benign prostate hyperplasia (BPH) with good urinary flow may still have bladder outlet obstruction (BOO). Intravesical prostatic protrusion (IPP) has been shown to be able to predict BOO. We aim to investigate the use of IPP to predict BOO in men with good urinary flow. METHODS: One hundred and fourteen consecutive men (>50 years old) presenting with lower urinary tract symptoms suggestive of BPH were recruited in 2001 and 2002. They were evaluated with serum prostate specific antigen (PSA), uroflowmetry and transabdominal ultrasound measurement of IPP and prostate volume (PV). Pressure-flow urodynamic studies were performed on all men and BOO was defined by BOO index > 40. Men with Q(max) ≥ 12.0 mL/s were considered to have good flow. RESULTS: Among the 114 men, 61 patients had good urinary flow. Their median age, PV and Q(max) were 66 years, 32.9 mm(3) and 14.5 mL/s respectively. 14/61 (23.0%) patients had BOO and their distribution of IPP were as follows: Grade 1 – 0/20 (0%) obstructed, Grade 2 – 6/22 (27.3%) and Grade 3 – 8/19 (42.1%). Sensitivity of Grade 2/3 IPP for BOO was 100% while specificity of Grade 3 IPP was 76.6%. The area-under-curve (AUC) for IPP was greater than that for PV (0.757 vs. 0.696). CONCLUSION: Even in men with good flow, high grades of IPP were more likely to have BOO and hence, may be a useful adjunct to predict BOO.