Analysis of Improved Urinary Peak Flow Rates After Robot-Assisted Radical Prostatectomy

Longitudinal assessment of prostatic obstruction has historically been assessed with urinary peak flow rates (PFR). In this observational study, we assess the impact of prostate removal on preoperative and postoperative PFRs after robot-assisted radical prostatectomy (RARP).

A single surgeon (TA) performed RARPs between 2002 and 2007. Men underwent routine preoperative uroflowmetric testing: 550 qualified for analysis with a sufficient voided volume (VV) of 150 mL preoperatively and at least once postoperatively. Continence and self-assessed American Urological Association (AUA) symptom and urinary quality of life (QoL) questionnaires were queried. Uroflows were analyzed preoperatively, short-term (3-15 mos), long-term (>2 y), and by age decades, lower urinary tract symptoms (LUTS) groups, and pathologic weight cohorts.

AUA and QoL scores improved from 8.1 and 1.6 at baseline to 4.4 and 1.0 at intermediate-term follow-up, P<0.01. Mean PFRs improved from a baseline 18.0 mL/s to 28.3, 30.8, and 36.5 at 3 months, 9 months, and >5 years follow- up (all P<0.001). Postvoid residual (PVR) volumes declined from 99 mL preoperatively to 24 mL at >5 years (P<0.01). Likewise, all age, LUTS, and prostate weight cohorts had significant improvements in PFR and PVR and stable voided volumes throughout the study.

The natural history of prostatic obstruction for men 40 to 80 years typically reveals reduction of mean PFRs. We observed that removal of the prostate resulted on average with a near doubling of PFRs and decreased PVRs (>50%) by 3 months. After RARP, the average PFR was reset to 25-30 mL/s, and these results were seen across all age, LUTS, and prostate weight groups; the gains remained stable 2 to 4 years after operation.