Correlation of Q-tip values and point Aa in stress-incontinent women

OBJECTIVE: To estimate the relationship between pelvic organ prolapse quantification (POP-Q) point Aa and straining Q-tip angle. METHODS: We compared preoperative straining Q-tip angles and Aa measurements from 655 women with predominant stress incontinence and urethral hypermobility (defined as a resting or straining angle of greater than 30°) using Pearson correlations and linear regression. Point Aa is 3 cm deep to the urethral meatus in the midline of the anterior vagina and corresponds to the urethrovesical crease. RESULTS: The median for point Aa was -1 cm (range -3 to +3 cm) and for straining Q-tip was 60° (30-130°). Twenty-nine percent of participants had an Aa at least 2 cm deep to the hymen, whereas in 69%, Aa was at or below -1 cm. The straining Q-tip angle was significantly different between these respective groups: 51.5° and 64° (P<.001). Linear regression analysis indicates that point Aa and straining Q-tip were moderately correlated (r=0.35, P<.001). As straining point Aa increased by 1 cm, Q-tip angle increased 4.6° (P<.001). Age and prior anterior vaginal or incontinence surgery had no significant effect on the correlation (P=.08 and P=.64, respectively). CONCLUSION: Nearly a third of stress-incontinent women with urethral mobility by Q-tip test visually appeared to have a well-supported urethrovesical junction with POP-Q point Aa values of -2 cm or less. The position of the urethrovesical crease (point Aa) on POP-Q and straining angle on Q-tip test do not appear to reflect the same anatomic support and cannot be used to predict one another. No Aa value can rule out urethral hypermobility.