The relationship of urethral resistance pressure and pressure flow parameters in women with lower urinary tract symptoms

This prospective study aims to evaluate the relationship between urethral resistance pressure (URP) and pressure flow parameters in women with lower urinary tract symptoms (LUTS). Consecutive women with LUTS attending three tertiary referral urodynamic clinics were asked to undergo urodynamic evaluation, pressure flow studies and URP measurement. The pressure flow parameters such as detrusor pressures at the start of flow (ODP), detrusor pressure at peak flow rate (PdetQmax), peak flow rate (Qmax) and detrusor pressure at the end of flow (CDP) were measured. The relationship between URP and pressure flow parameters was evaluated as well as differences between each urodynamic group. Two hundred seventy-nine women attended for urodynamic investigations. Two hundred twenty-three (79.9%) women had good quality pressure flow measurements and were included in the study. The mean age was 58 years (range 21-83). Women with urodynamic stress incontinence had significantly lower URP and ODP than those with detrusor over-activity [54.8 (+/-17.9) and 12.4 (+/-4.1) cmH(2)O, respectively, vs 85.6 (+/-21.4) and 33.7 (+/-13.3) cmH(2)O, respectively) (p<0.05, Bonferroni test). Furthermore, women with urodynamic stress incontinence have significantly lower PdetQmax values as well as higher Qmax than women with competent urethral sphincters (p<0.05, Bonferroni test). There was a significant correlation between ODP, PdetQmax, Qmax and URP measurements. In urodynamic stress incontinence, both URP and pressure flow parameters are reduced. Although the trend for values of both tests were similar and there was a significant correlation between these tests, we should consider that urethral function at rest differ from that during voiding due to activation of additional mechanisms. Therefore, further study is needed to confirm our results.