Which Is a Better Indicator of Bladder Outlet Obstruction in Patients with Benign Prostatic Enlargement – Intravesical Protrusion of Prostate or Bladder Wall Thickness?

Objective: to determine the correlation of intravesical prostatic protrusion(IPP) and bladder wall thickness (BWT) with clinical and urodynamic parameters,as well as their sensitivity and specificity with regard to bladder outletobstruction in patients with a benign prostatic enlargement (BPE). Materials andmethods: 111 patients with lower urinary tract symptoms and confirmed BPEcompleted the International Prostatic Symptom Score (I-PSS), as well as a transabdominalultrasound to determine their prostate volume, a grade of IPP and BWT.All the patients were then subjected to the complete urodynamic studies (UDS).Results: the IPP showed a good correlation with the prostate volume (r=0.61) andserum PSA (r=0.48); p=0.0000, free uroflowmetry (r=-0.27; p=0.004), as well as thedeterminants of urodynamic obstruction: bladder outlet obstruction index–BOOI(r=0.36; p 0.0001), and ICS and Schaefer obstruction class nomograms (rho=0.33and rho=0.39, respectively; p 0.001), while the BWT showed only a statistical correlationwith age (r=0.23; p=0.02) and serum PSA (r=0.4; ,p=0.0000), regardless ofan significant correlation with the IPP (r=0.45; p=0.0000). The ANOVA test showeda significant difference between the IPP grades for the observed clinical and urodynamicvariables with an increase in significance for IPP 10 mm. The area underthe ROC curve in the prediction of obstruction for the IPP is 0.71 (sensitivity 59.6,specificity 81.4), while the AUC for the BWT is 0.61 (sensitivity 64.5, specificity 59.2).The stepwise logistic regression model shows that most significant independentvariables for the obstruction are the IPP, Qmaxfree and age, with the area under theROC curve of 0.78 (95% CI 0.695 to 0.856). Conclusion: The IPP higher than 10mm as a non-invasive predictor of infravesical obstruction shows good correlationswith clinical and urodynamic parameters, while the specificity and PPV againstobstruction are significant. Despite a good correlation with IPP, the BWT is only amodest indicator of obstruction. .