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.
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