Does the Combination of i ntravesiC al ProstatiC Protrusion anD b laDD er o utlet o bstru Ction number i n Crease test aCC ura Cy aCC orD ing to

Objective: Determine diagnostic power and intercorrelation between bladder outlet obstruction number (BOO n) and intravesical prostatic protrusion (ipp) as non-invasive predictors of infravesical obstruction in patients with lower urinary tract symptoms due to benign prostatic enlargement. Mate rial and methods: prospective study during 2009-2010 analyzed data of 110 patients with proven benign prostatic enlargement. prostate volume and ipp were determined by transabdominal ultrasound, and patients underwent complete urodynamic studies (UDS). BOOn was calculated using the formula: prostate volume (cc)-3 x Qmax (ml/s)-0.2 x mean voided volume (ml). r esults: There is a statistically significant correlation between the values of ipp and BOOn (Spearman’s rank correlation coefficient rho=0.48, p=0.0001). BOOn is a more sensitive (sensitivity 82.4%, specificity 66.1%), while ipp is a more specific factor (sensitivity 58.8%, specificity 81.4%) in the group-wise prediction of bladder outlet obstruction (BOO). p ositive predictive value in the diagnosis of obstruction increases at the individual level combining the cut-off values for BOOn>-30, with ipp>10 mm (ppV 86.8%). Owing to a good correlation of ipp with different definitions of urodynamic obstruction, ipp was included in the BOO n formula instead of prostate volume. This number was arbitrarily called BOO n2. The combination of ipp >10 mm and cut-off value for BOOn2 >-50 showed that 88.6% of the patients were accurately classified in the zone of obstruction (mean ipp 14.9 mm), while BOO n2<-50 carried a high npV. Conclusion: The combination of cut-off values for BOOn and ipp increases test accuracy according to BOO at the individual level, thus facilitating clinical decision making regarding diagnostics and optimal choice of therapy in patients with B pe. Owing to its good correlation with obstruction determinants, ipp can be included in the formula for BOO n instead of prostate volume.