A new urodynamic measurement system for urethral retroresistance pressure (URP) has been described. URP is defined as the pressure required to achieve and maintain an open urethral sphincter and is measured by occluding the urethral meatus with a cone-tipped plug placed 5 mm in the urethra.

Sterile fluid is then infused retrograde at a rate of 1 mm/s while the required pressure is measured on a pressure vs time plot, and the plateau of the asymptotic curve represents the URP ^(10,11).

In a randomized, multicenter trial of 258 symptomatic females, URP, LPP, and MUCP were measured after assessment of incontinence severity by validated questionnaires.

The authors concluded that URP has a consistent relationship to incontinence severity, whereas MUCP and LPP were not reliably decreased in patients with increased degrees of incontinence ⁽¹⁰⁾. In a second study, 61 asymptomatic females underwent URP measurement after confirming a negative standing stress test; the goal was to characterize the distribution and reproducibility of URPs in asymptomatic women ⁽¹¹⁾.

Urodynamic Evaluation of Female Stress Urinary Incontinence - Introduction - Leak-Point Pressures - Urethral pressure profilometry - Urethral Retroresistance Pressure - Role of Urodynamic Testing in the Assessment of Female SUI

The URP measurements in this population exhibited a normal distribution, and in 32 females who underwent retesting 3–7 d later, there was no statistically significant difference between test and retest URP measurements. Furthermore, when comparing the symptomatic and asymptomatic premenopausal patients, the mean URP was significantly different.

This work represents an attempt to define and characterize a novel approach to measuring urethral function with the goal of finding a parameter that is reproducible, accurately identifies stress incontinent patients, and predicts treatment outcome. Although initial investigations of URP are promising, it remains investigational and will require further evaluation before its clinical utility can be determined.

——
Kelly M. Maxwell, MD, and J. Quentin Clemens, MD, MSCI
——

REFERENCES

1. Leach GE, Dmochowski RR, Appell RA, et al. Female Stress Urinary Incontinence Clinical Guidelines Panel summary report on surgical management of female stress urinary incontinence. J Urol 1997;158: 875-880.
2. McGuire EJ, Fitzpatrick CC, Wan J, et al. Clinical assessment of urethral sphincter function. J Urol 1993;150(5 pt 1):1452-1454.
3. Stiltberg H, Larsson G, Victor A. Reproducibility of a new method to determine cough-induced leak-point pressure in women with stress urinary incontinence. Int Urogynecol J 1996;7:13-19.
4. Bump RC, Elser DM, McClish DK. Valsalva leak point pressures in adult women with genuine stress urinary incontinence: reproducibility, effect of catheter caliber, and correlations with passive urethral pressure profilometry. Neurourol Urodyn 1993;12:307-308.
5. Rud T, Andersson KE, Asmussen M, Hunting A, Ulmsten U. Factors maintaining the intraurethral pressure in women. Invest Urol 1980;17:343-347.
6. Bonney V. On diurnal incontinence of urine in women. J Obstet Gynaecol Br Emp 1923;30:358-365.
7. Lose G, Griffiths D, Hosker G, et al. Standardisation of urethral pressure measurement: report from the Standardisation Sub-Committee of the International Continence Society. Neurourol Urodyn 2002;21:258-260.
8. Weber AM. Is urethral pressure profilometry a useful diagnostic test for stress urinary incontinence? Obstet Gynecol Surv 2001;56:720-735.
9. Bump RC, Copeland WE, Jr, Hurt WG, Fantl JA. Dynamic urethral pressure/profilometry pressure transmission ratio determinations in stress-incontinent and stress continent subjects. Am J Obstet Gynecol 1988;159:749-755.
10. Slack M, Culligan P, Tracey M, Hunsicker K, Patel B, Sumeray M. Relationship of urethral retroresistance pressure to urodynamic measurements and incontinence severity. Neurourol Urodyn 2004; 23:109-114.
11. Slack M, Tracey M, Hunsicker K, Godwin A, Patel B, Sumeray M. Urethral retro-resistance pressure: a new clinical measure of urethral function. Neurourol Urodyn 2004;23:656-661.
12. Diokno AC, Dimaculangan RR, Lim EU, Steinert BW. Office based criteria for predicting type II stress incontinence without further evaluation studies. J Urol 1991;161:1263-1267.
13. Weber AM, Taylor RJ, Wei JT, Lemack G, Piedmonte MR, Walters MD. The cost-effectiveness of preoperative testing (basic office assessment vs urodynamics) for stress urinary incontinence in women. BJU Int 2002;89:356-363.
14. Liapis A, Bakas P, Salamalekis E, Botsis D, Creatsas G. Tension-free vaginal tape (TVT) in women with low urethral closure pressure. Eur J Obstet Gynecol Reprod Biol 2004;116:67-70.
15. Paick JS, Ku JH, Shin JW, Son H, Oh S, Kim SW. Tension-free vaginal tape procedure for urinary incontinence with low Valsalva leak point pressure. J Urol 2004;172:1370-1373.