CORRELATION OF Q-TIP VALUES AND POINT AA IN STRESS INCONTINENT WOMEN

H. Zyczynski, L.K. Lloyd, K. Kenton, S. Menefee, M. Boreham, A. M. Stoddard, for the Urinary Incontinence Treatment Network

Magee Women’s Hospital, Pittsburgh, PA

OBJECTIVE:  To determine the relationship between POP-Q point Aa and maximum urethral straining angle (Q-tip_strain) and if the relationship is affected by pelvic organ prolapse in a cohort of women with stress predominant urinary incontinence.   

MATERIALS AND METHODS:  Maximum urethral straining angles and Aa measurements were obtained from 655 women with stress predominant urinary incontinence and urethral hypermobility enrolled in a randomized surgical trial comparing the retropubic urethropexy and the sling procedures.   Urethral hypermobility was measured with the Q-tip test, using a goniometer, and defined by a resting angle or displacement angle >30º from the horizontal plane. Point Aa was measured relative to the hymen in the midline of the anterior vagina with a centimeter ruler with the subject in the supine position, straining maximally.   Pearson correlations and linear regression analyses were performed on baseline measures obtained prior to surgery. 

RESULTS: Subjects had a mean±SD age and BMI of 51±10 years and 30±6.5 kg/m2, respectively. The median for point Aa was -1 cm (range –3cm to +3cm ) and the median for Q-tip_strain  was 60o (range 10° to 130°) . The distribution of point Aa is displayed below.

Point Aa	Equal to or above -2cm	-1cm up to -2cm	Below -1cm
Frequency	29%	28%	43%

The distribution of overall stage of prolapse was 25% stage 0/I, 59% stage II, 16% stage III/IV.  Fifteen percent reported a history of prior anterior vaginal or incontinence surgery.

Point Aa and Q-tip_strain were weakly correlated (r=0.34, p<.0001). Results of a  linear regression  show that as maximum straining angle increases 1 degree, Aa increases 0.026 cm (p<0.0001).  When POP-Q stage was held constant in the regression model, as Q-tip_strain  increases 1 degree, Aa increases only 0.014 cm (p<0.0001).  Therefore, the positive correlation between Aa and Q-tip_strain is not independent of prolapse stage.    Age and prior anterior vaginal wall or incontinence surgery had no significant effect on the correlation between Aa and Q-tip_strain  (p=0.07, p=0.64 respectively).    

CONCLUSIONS:  There is a weak relationship between point Aa and Q-tip_strain  angle in this sample of stress incontinent women.  As the degree of urethral hypermobility increases, Point Aa becomes more prolapsed.  However, one value does not predict the other.   Our findings suggest that an Aa value distal to –2cm is a poor indicator of urethral hypermobility because it would exclude 29% of the population who meet the criterion for urethral hypermobility based upon the Q-tip test.   

Key Words:  Q-tip, POP-Q, urethral mobility

Disclosure - Grant/Research: H. Zyczynski, Boehringer Ingelheim, Lilly; K Kenton, Pfizer; L.K. Lloyd, Ortho-McNeil, Celgene; Speakers Bureau: H. Zyczynski,  Pfizer, Boehringer Ingelheim; Muriel Boreham, Ortho, Pharmacia, Watson; S Menefee, Boston Scientific; L.K.Lloyd, Pfizer, Watson, Ortho-McNeil, Lilly-Icos, GlaxoSmith Kline; Consultant: L.K. Lloyd, Pfizer, Watson, Ortho-McNeil, Lilly-Icos, GlaxoSmith Kline.