Chronological Urodynamic Evaluation of Changing Bladder and Urethral Functions After Robot-assisted Radical Prostatectomy

OBJECTIVE To examine chronological changes in urethral and bladder functions before, immediately after, and 1 year after robot-assisted radical prostatectomy (RARP), urodynamic studies were prospectively performed. METHODS Sixty-three consecutive patients underwent pressure-flow studies, urethral pressure profiles, and abdominal leak point pressure (ALPP) tests 1-2 days before, immediately after, and 1 year after RARP. RESULTS The mean bladder compliance was 28.3 mL/cm H2O before RARP; it worsened to 16.3 mL/cm H2O immediately after RARP and recovered to 27.1 mL/cm H2O at 1 year. The mean detrusor pressure at maximum flow rate was 61.9 cm H2O before RARP; it decreased to 34.3 cm H2O immediately after RARP and remained at 35.6 cm H2O at 1 year. The mean maximum urethral closure pressure was 84.2 cm H2O before RARP; it decreased to 33.4 cm H2O immediately after RARP and recovered to 63.0 cm H2O at 1 year. Intrinsic sphincter deficiency (ISD) evaluated by the ALPP test was observed in 53 patients immediately after RARP, although no patient showed ISD before RARP. ISD remained in 7 patients at 1 year. Both ALPP and maximum urethral closure pressure at 1 year were significant factors for continence in multivariate analysis. CONCLUSION Urethral sphincter and bladder function worsen immediately after RARP and recover over time. The bladder storage function after RARP returns to almost the same level before RARP, and the voiding function improves compared with the condition before RARP; however, the urethral sphincter function does not return to its preoperative level. Urethral sphincter dysfunction is considered the main factor for urinary incontinence after RARP. (C) 2015 Elsevier Inc.