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 International Prostate Symptom Score, 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/m² before and 28.2 ± 3.53 g/m² 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.