Change of Ultrasound Estimated Bladder Weight and Bladder Wall Thickness After Treatment of Bladder Outlet Obstruction With Dutasteride

Objectives To investigate the change of bladder wall hypertrophy to relieve bladder outlet obstruction ( BOO ) by treatment with 5α‐reductase inhibitor. Methods Men who have BOO confirmed by urodynamic study ( BOO index ≥40) were treated with dutasteride 0.5 mg once a day for 6 months. We measured ultrasound estimated bladder weight ( UEBW ), UEBW divided by body surface area ( UEBW / BSA ), and bladder wall thickness ( BWT ) before and after treatment. Changes in LUTS parameters were assessed by using the I nternational P rostate S ymptom S core, uroflowmetry, residual urine volume, prostate volume, serum prostate‐specific antigen ( PSA ), and LUTS outcome scores ( LOS ). Correlation between the change of LUTS parameters and UEBW , UEBW / BSA , and BWT were evaluated. We assessed the changes of bladder wall hypertrophy according to the results of benefit, satisfaction, and willingness to continue ( BSW ) questionnaire. Results Thirty patients completed the 6‐month study. The mean UEBW was 47.10 ± 7.79 g before and 50.07 ± 5.39 g after dutasteride treatment ( P  = 0.259). The mean UEBW / BSA was 26.47 ± 4.30 g/m 2 before and 28.2 ± 3.53 g/m 2 after treatment ( P  = 0.253), and there was no definite change in mean BWT after treatment ( P  = 0.301). Most LUTS parameters including LOS significantly improved. Increased BOO index value was related to decreased BWT (ρ = 0.361, P  = 0.049). There was no definite change in mean UEBW , UEBW / BSA , and BWT according to the results of the BSW questionnaire. Conclusions There was no change in UEBW , UEBW / BSA and BWT despite improving most clinical parameters suggesting BOO . The changes of bladder wall hypertrophy parameters still have limitations to directly reflect the relief of BOO .