Vaginal Swab Test Compared With the Urethral Q-tip Test for Urethral Mobility Measurement: A Randomized Controlled Trial.

OBJECTIVE

To assess whether use of a vaginal cotton-tipped swab is equivalent to the standard Q-tip test regarding urethral mobility. Secondarily, to examine whether both tests agree in hypermobility diagnosis, discomfort level, and patients' preference.

METHODS

In this randomized crossover trial, women with stress urinary incontinence without prolapse beyond the hymen were randomized to undergo either a vaginal or urethral mobility test first followed by the alternate approach. The primary outcome was the difference in rotation angle, from resting to maximum strain, between tests. The equivalence margin was ±10°. The secondary outcome was agreement in hypermobility diagnosis using two definitions: 1) maximum straining angle of 30° or greater from the horizontal plane; and 2) rotation angle 30° or greater. Discomfort was assessed using a 0-10 visual analog scale. Using 90% power assuming a standard deviation of 20°, 36 and 139 patients were needed for 10° and 5° equivalence margins, respectively.

RESULTS

From January 2014 to March 2015, 140 women were randomized. The mean difference between the two tests was 5.1° (95% confidence interval 3.2-6.9°), meeting the predefined equivalence criteria. In the hypermobility diagnosis, the urethral and vaginal tests had no disagreement using definition 1 (P=.23), whereas the two tests disagreed using definition 2 (P=.03). The urethral approach had a higher discomfort level (P<.001). The majority preferred the vaginal test (68% preferred vaginal, 32% no preference).

CONCLUSION

The vaginal swab test is equivalent to the standard Q-tip test in measuring urethral mobility with less discomfort and is preferred by patients.