Related Experiment Videos
The effect of urethral pressure variation on detrusor activity in women
1Department of Obstetrics and Gynecology, Dalhousie University, Halifax, Nova Scotia, Canada.
Insights
This study identified three urethral pressure variation patterns, with rapid pressure variation (RPV) strongly linked to detrusor instability. Understanding these patterns may clarify causes of unstable detrusor contractions.
Area of Science:
- Urology
- Urodynamics
- Lower Urinary Tract Physiology
Background:
- Urethral pressure variation and its impact on detrusor activity are not fully understood.
- Establishing diagnostic criteria for urethral pressure variation is necessary.
Purpose of the Study:
- To confirm known patterns of urethral pressure variation.
- To establish diagnostic criteria for these patterns.
- To examine the effect of urethral pressure variation on detrusor activity.
Main Methods:
- Retrospective review of 26-month computerized cystometric tracings.
- Analysis of 41 patient tracings with urethral pressure variation and/or detrusor instability.
- Statistical analysis using Fisher's exact test and independent t-test.
Main Results:
- Three patterns identified: rapid pressure variation (RPV), gradual pressure variation (GPV), and stress-induced transient urethral relaxation (SITUR).
- RPV associated with low bladder volumes and detrusor instability (P < 0.001).
- GPV associated with high bladder volumes (P < 0.001).
- RPV frequently preceded unstable detrusor contractions (P < 0.003).
Conclusions:
- Three distinct patterns of urethral pressure variation were identified.
- Rapid urethral pressure variation is closely associated with detrusor instability.
- Further research into urethral pressure variation may elucidate mechanisms of idiopathic unstable detrusor contractions.
Abstract:
The purposes of this study were to confirm previously described patterns of urethral pressure variation and to establish criteria for their diagnosis. The effect of urethral pressure variation on detrusor activity was also examined. The study involved a retrospective review of the computerized cystometric tracings from a 26-month period. Forty-one patients had artefact-free satisfactory tracings demonstrating urethral pressure variation, detrusor instability and/or gradual detrusor pressure increase. These tracings were stored on a computer program which permitted real-time second-by-second review. Statistical analysis was done using Fisher's exact test and an independent t-test. Three patterns of urethral pressure variation were identified: rapid pressure variation (RPV), gradual pressure variation (GPV) and stress-induced transient urethral relaxation (SITUR). RPV was associated with onset at low bladder volumes (independent t-test, P = 0.02) and with detrusor instability (Fisher's exact test, P < 0.001). GPV began at high bladder volumes (Fisher's exact test, P < 0.001). SITUR was not associated with any specific pattern of urethral pressure variation or detrusor pressure change. Analysis of tracings of the patients with a combination of rapid urethral pressure variation and detrusor instability revealed a statistically significant increased frequency of urethral relaxation as the primary event precipitating an unstable detrusor contraction (Fisher's exact test, P < 0.003). In conclusion, three different patterns of urethral pressure variation were identified. Rapid pattern of urethral pressure variation is closely associated with detrusor instability. Further study of urethral pressure variation may help to elucidate the pathophysiologic mechanism responsible for idiopathic unstable detrusor contractions.