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The Q-tip test and urethrovesical junction mobility
1Department of Obstetrics and Gynecology, Methodist Hospital of Indiana, Indianapolis.
Objective:
To determine the accuracy of the Q-tip test to measure urethrovesical junction mobility.
Methods:
One hundred fourteen women with urinary incontinence or genital prolapse were evaluated with a Q-tip test and perineal ultrasound scanning to measure urethrovesical junction mobility with strain. The sensitivity, specificity, and positive and negative predictive values of the Q-tip test to diagnose urethrovesical junction hypermobility were calculated using ultrasound as the standard. Repeat Q-tip and ultrasound measurements were obtained in ten subjects and analyzed for reproducibility.
Results:
The Q-tip test had a sensitivity of 25%, specificity of 78%, positive predictive value of 67%, and negative predictive value of 37%. The Q-tip and ultrasound measurements were reproducible, as the within-subject variation was significantly small when compared to between-subject variation (P = .0001).
Conclusion:
The Q-tip test is inaccurate for measurement of urethrovesical junction mobility and should not be used in the manner described to diagnose urethrovesical junction hypermobility.