Comparison of the Q-tip test and voiding cystourethrogram to assess urethral hypermobility among women enrolled in a randomized clinical trial of surgery for stress urinary incontinence

Abstract

Purpose: We compared 2 measures of urethral hypermobility, the Q-tip test and voiding cystourethrogram, preoperatively in women recruited in 1 center participating in a multicenter randomized clinical trial comparing Burch colposuspension with autologous rectus fascia sling.

Materials and methods: Following institutional review board approval, women with stress urinary incontinence and pelvic organ prolapse stage 2 or less underwent a standardized standing voiding cystourethrogram and a Q-tip test at a 45 degree angle reclining position preoperatively. Urethral angle at rest and straining were measured with a radiological ruler (voiding cystourethrogram) or goniometer (Q-tip) by 2 different investigators blinded to each other findings.

Results: In 43 patients the mean urethral angle at rest and UAS were 20 degrees +/- 12 and 51 degrees +/- 20, by voiding cystourethrogram compared to 16 degrees +/- 9 and 58 degrees +/- 10 by Q-tip test, respectively. The mean angle difference (urethral angle with straining minus urethral angle at rest) was greater for the Q-tip test (42 degrees +/- 9) than that for the voiding cystourethrogram test (32 degrees +/- 17; p < 0.05). Fewer patients (14% by Q-tip, 28% by voiding cystourethrogram) had urethral hypermobility using the definition of urethral angle at rest greater than 30, while almost all patients (91% by voiding cystourethrogram, 100% by Q-tip) had urethral hypermobility using the definition of urethral angle with straining greater than 30. However, using the definition of urethral angle with straining minus urethral angle at rest greater than 30, only 58% of patients had urethral hypermobility by voiding cystourethrogram compared to 98% by Q-tip.

Conclusions: The voiding cystourethrogram and the Q-tip test measure urethral hypermobility differently. This may affect which patients are classified as having urethral hypermobility, and the choice of anti-incontinence surgery.