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Obstetrics & Gynecology 2005;105:115-119
© 2005 by The American College of Obstetricians and Gynecologists
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ORIGINAL RESEARCH

Evaluation of Aa Point and Cotton-Tipped Swab Test as Predictors of Urodynamic Stress Incontinence

Karen Tapp, MD, AnnaMarie Connolly, MD and Anthony G. Visco, MD

From the Division of Urogynecology/Reconstructive Pelvic Surgery, Department of Obstetrics and Gynecology, University of North Carolina School of Medicine, Chapel Hill, North Carolina.

Address reprint requests to: AnnaMarie Connolly, MD, Division of Urogynecology/Reconstructive Pelvic Surgery, Department of Obstetrics and Gynecology, University of North Carolina School of Medicine, 4036 Old Clinic Building, CB #7570, Chapel Hill, NC 27599–7570; e-mail: amc004{at}med.unc.edu.


   ABSTRACT
TOP
ABSTRACT
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
OBJECTIVE: To compare the predictive abilities of the Aa point of the pelvic organ prolapse quantification examination and the cotton-tipped swab test straining angle to diagnose urodynamic stress incontinence.

METHODS: A case-control study was conducted between June 1997 and February 2003. Cases were defined as patients with urodynamic stress incontinence (n = 352). Controls were patients who also underwent urodynamic testing but who did not have a diagnosis of urodynamic stress incontinence (n = 245). Independent variables were defined as Aa point, Aa point of 0 or greater, straining cotton-tipped swab angle, and straining cotton-tipped swab angle of 30° or greater. Logistic regression estimated the odds ratio of stress incontinence in women based on Aa values and cotton-tipped swab straining angle measurements, controlling for other variables commonly associated with stress incontinence.

RESULTS: The mean (± standard deviation) age of the cases was 55.9 ± 13.4 and of controls was 55.3 ± 14.8, (P = .6). The median parity of the cases was 2 (range 0–10) and of controls, 2 (range 0–9) (P = .7). The Aa point was not associated with a diagnosis of stress incontinence (odds ratio 1.01, 95% confidence interval (CI) 0.83–1.23). The adjusted odds ratios of having an Aa value of 0 or greater was 0.49 (95% CI 0.26–0.92), and of having a cotton-tipped swab angle of 30° or greater was 3.1 (95% CI 1.09–5.07), in a model that adjusted for age, parity, race, and postmenopausal and hormonal replacement status.

CONCLUSION: Aa point is not associated with a diagnosis of stress incontinence. However, a cotton-tipped swab angle of 30° or greater is positively associated with stress incontinence.

LEVEL OF EVIDENCE: II-2

Urethral hypermobility has long been associated with stress urinary incontinence. With loss of support and descent of the urethrovesical junction, intra-abdominal pressure is not transmitted equally to the bladder and urethra, and involuntary loss of urine during times of intra-abdominal straining may occur. The goal of commonly used procedures is to improve the support of the urethrovesical junction. A woman has been considered a good candidate for a bladder neck suspension if she has poor support of the urethrovesical junction and proven stress incontinence.1

Since its description in 1971 by Crystle et al,2 the cotton-tipped swab test has become a widely used office test for assessing proximal urethral mobility in women with symptoms of stress urinary incontinence.3 Urethral hypermobility is anecdotally defined as a urethral straining angle of 30° or greater, but it is not known how much rotation with strain is clinically significant.4 Although inexpensive and simple to perform, the measurement itself requires correct placement of the cotton-tipped swab at the bladder neck and can be uncomfortable to the patient.5 Many studies have questioned the validity of the cotton-tipped swab test, yet it remains one of the most popular clinical tests in assessing the mobility of the urethrovesical junction.6 For many surgeons diagnosing and treating stress urinary incontinence, the cotton-tipped swab test result may determine which type of surgery is recommended. Therefore, the cotton-tipped swab test should be a reliable and accurate indicator of stress incontinence.

In 1996, the pelvic organ prolapse quantification system was accepted by the International Continence Society for standardized staging of pelvic organ prolapse. Studies since 1996 have shown that the pelvic organ prolapse quantification system has good reproducibility of measures and that the reliability is independent of examiner experience.7 The pelvic organ prolapse quantification point Aa, located in the midline anterior vaginal wall, 3 cm cephalad to the external urethral meatus, corresponds to the approximate location of the urethrovesical junction. If the pelvic organ prolapse quantification examination provides an accurate assessment of the anterior vaginal wall, and Aa represents the approximate anatomic location of the urethrovesical junction, other tests of hypermobility, such as the cotton-tipped swab test, may not be necessary.

Several studies have evaluated the use of the cotton-tipped swab test in determining urethrovesical junction mobility. A well-supported urethra has been described in 10–40% of women with stress urinary incontinence, whereas up to 50% of continent women have urethral hypermobility as defined by cotton-tipped swab straining angle of 30° or greater.8 However, the Aa point and the cotton-tipped swab straining angle have been found to have a moderate degree of correlation (Spearman correlation coefficient 0.47; P < .001).9 The predictive ability of the Aa point to diagnose stress urinary incontinence has not been previously examined.

The objective of this study was to compare the predictive abilities of the Aa point and the cotton-tipped swab test straining angle to diagnose urodynamic stress incontinence. We hypothesized that the Aa point was a better predictor of stress incontinence than the cotton-tipped swab test, affording gynecologists a less invasive, more predictable indicator of stress incontinence.


   MATERIALS AND METHODS
TOP
ABSTRACT
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
After obtaining Institutional Review Board approval from the University of North Carolina, School of Medicine, a case-control study was performed. Data from 867 consecutive women undergoing multichannel urodynamic testing at the University of North Carolina at Chapel Hill from June 1997 to February 2003 were examined. All medical records were reviewed for demographics, physical examination findings, and urodynamic diagnosis. The International Continence Society definition of urodynamic stress incontinence was used. The pelvic organ prolapse quantification examinations were performed by members of the Urogynecology and Reconstructive Pelvic Surgery Division in the standard fashion, with women in the supine lithotomy position on a standard gynecologic examination table. Women were asked to perform a Valsalva maneuver to obtain the maximum descent of prolapse. The pelvic organ prolapse quantification point Aa is located in the midline anterior vaginal wall, 3 cm cephalad to the external urethral meatus. The maximum descent of point Aa was measured in centimeters in relation to the hymen. Negative Aa points were proximal to the hymen; positive measurements were distal to the hymen. The standard scale, –3 (no descent) to +3, was used. The same examiner also performed the cotton-tipped swab test. A sterile, lubricated cotton-tipped swab was inserted transurethrally and withdrawn until resistance was met, suggestive of the urethrovesical junction. The angle relative to the horizontal was measured at rest and with straining in the standard fashion using a protractor level with the floor. The same providers performed all the pelvic organ prolapse quantification exams, cotton-tipped swab tests, and urodynamic studies.

Cases were defined as women with the diagnosis of urodynamic stress incontinence. Controls were defined as women who underwent urodynamic testing but did not have a diagnosis of urodynamic stress incontinence. Women who did not have both pelvic organ prolapse quantification examinations and cotton-tipped swab tests performed were excluded (n = 270). Independent variables examined included Aa point (range –3 to +3), Aa equal to or greater than 0, cotton-tipped swab straining angle, and cotton-tipped swab greater than or equal to 30°. The dichotomous variables, point Aa greater than or equal to 0 and cotton-tipped swab angle greater than or equal to 30°, were analyzed. Statistical analysis was performed using Student t test, {chi}2, Wilcoxon rank sum test, and logistic regression where appropriate (SAS 8.01, SAS Institute, Cary, NC). A logistic regression model with urodynamic stress incontinence as the dependent variable and with Aa point of 0 or greater, cotton-tipped swab straining angle 30° or greater, age, race, parity, and postmenopausal and hormone replacement status as predictors was constructed. Unadjusted and adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were determined. Statistical significance was defined as {alpha} < 0.05.


   RESULTS
TOP
ABSTRACT
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
Patient demographics and baseline variables are presented in Table 1. A total of 352 cases with a diagnosis of urodynamic stress incontinence and 245 controls without a urodynamic diagnosis of stress urinary incontinence were identified. The mean ages of the cases and controls were not significantly different, 55.9 ± 13.4 versus 55.3 ± 14.8, (P = .6), respectively. The median parity for both the cases and controls was 2 (P = .7).


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  		Table 1. Patient Demographics/Baseline Variables

 

There was also no difference between groups regarding parity, smoking history, body mass index, prior hysterectomy, prior incontinence surgery or prolapse surgery, postmenopausal status, or postvoid residual. Cases were significantly less likely to be African American compared with controls (6% versus 12%, P = .01) and more likely to be on hormone replacement therapy (48% versus 34%, P < .001).

Unadjusted and adjusted odds ratios for the diagnosis of urodynamic stress incontinence are presented in Table 2. The Aa point was not associated with stress incontinence (odds ratio 1.01, 95% CI 0.83–1.23). In fact, the adjusted odds ratio of having an Aa value of 0 or greater was 0.49 (95% CI 0.26–0.92), indicating a 51% reduced risk of having a urodynamic diagnosis of stress incontinence. Conversely, a cotton-tipped swab straining angle of 30° or greater was associated with a urodynamic diagnosis of stress incontinence. Among the cases, women with a urodynamic diagnosis of stress urinary incontinence, the OR of having a cotton-tipped swab angle of 30° or greater was 2.91 (95% CI 2.02–4.18). This association retained its significance after controlling for age, parity, race, and postmenopausal and hormonal replacement therapy status, and Aa value with an OR of 3.10 (95% CI 1.90–5.07). African-American race was negatively associated with stress incontinence, with an adjusted OR of 0.45, (95% CI 0.24–0.84). Hormone replacement therapy use was associated with an increased risk of urodynamic stress incontinence, with an adjusted OR of 1.86, (95% CI 1.16–2.98).


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  		Table 2. Unadjusted and Adjusted Odds Ratios for the Diagnosis of Urodynamic Stress Incontinence

 

In this study, the sensitivity of the cotton-tipped swab test for predicting stress incontinence was 80% (95% CI 0.75–0.84%), with a specificity of 42% (95% CI 0.36–0.49%), negative predictive value of 59% (95% CI 0.52–0.67%), and positive predictive value of 67% (95% CI 0.62–0.71%). The Aa point had a sensitivity of 37% (95% CI 0.32–0.43%), specificity of 58% (95% CI 0.51–0.64%), negative predictive value of 39% (95% CI 0.34–0.44%), and positive predictive value of 56%, (95% CI 0.49–0.63%).


   DISCUSSION
TOP
ABSTRACT
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
Various methods have been used to assess urethrovesical junction mobility. These include bead-chain cystography, fluoroscopy, ultrasonography, and cotton-tipped swab testing.10–14 Each of these procedures involves either radiation exposure and/or instrumentation for the patient. This study compared a noninvasive Aa point measurement with the cotton-tipped swab test to determine which better predicts urodynamic stress incontinence. Although urethrovesical junction hypermobility may reflect loss of anatomic support of the bladder base, its contribution to the pathophysiology of stress incontinence remains unclear.

We hypothesized that, given its reproducibility of measures and reliability, the pelvic organ prolapse quantification examination Aa point would be a better and less-invasive predictor of incontinence. We found that the Aa point was not associated with the urodynamic diagnosis of stress incontinence. This is supported by previously published data that the pelvic organ prolapse quantification examination measures descent of vaginal topography, but not which organ is descending with the point on the mucosa.15 The cotton-tipped swab test straining angle of 30° or greater was a better predictor of the diagnosis of stress incontinence (adjusted OR 3.10, 95% CI 1.90–5.07). The sensitivity and specificity of the cotton-tipped swab test in predicting stress incontinence (80% and 42%, respectively) in this study are similar to values reported by other investigators.1

We found that African-American race was negatively associated with urodynamic stress incontinence (OR 0.45, 95% CI 0.24–0.84). This finding is consistent with other studies. Sze et al16 compared the prevalence of urinary incontinence symptoms among black, white, and Hispanic women from different socioeconomic and educational backgrounds and found that more white women reported urinary incontinence than did black or Hispanic women (41% versus 31% versus 30%, P < .001) and that white women had a higher prevalence of stress incontinence symptoms (39% versus 27% versus 24%, P < .001). The percentage of women who had urge incontinence symptoms was very similar among the 3 groups. However, the diagnosis of stress versus urge incontinence was based on symptoms alone and not on urodynamic studies. Other studies have also found this association.17

In this study we found an increased prevalence of urodynamic stress incontinence in patients using postmenopausal hormone therapy (OR 1.86, 95% CI 1.16–2.98). Several randomized trials have indicated that hormone replacement therapy does not improve urinary symptoms.18–20 Indeed, 2 recent publications have shown that women on hormone replacement therapy are more likely to experience urinary incontinence than nonusers. A randomized trial from the Heart and Estrogen/Progestin Replacement Study18 looked at incontinence symptoms in 1,525 women with coronary disease and found that women on conjugated estrogen and medroxyprogesterone acetate were 45% more likely (P = .001) to experience a worsening in their incontinence symptoms than women given placebo. Looking at the incidence of urinary incontinence from 1996 to 2000, the Nurses’ Health Study identified 5,060 incident cases of occasional (leakage 1–3 times/month) and 2,495 cases of frequent incontinence (leakage at least weekly). The risk of incontinence was elevated among women taking postmenopausal hormones compared with women who had never taken hormones (relative risk 1.34–1.68), depending on the formulation and route of delivery.20 In both of these studies, information was not available on the type of incontinence (stress versus urge), and no formal urodynamic studies were performed to confirm the diagnosis.

The limitations of this study include its retrospective design. Although pelvic organ prolapse quantification examinations and cotton-tipped swab tests were performed by the same examiner on each patient, multiple providers did participate in this study. Selection bias may be present because all patients had access to medical care. The pelvic organ prolapse quantification examination may also have limitations. The Aa point approximates urethrovesical junction location, but this approximation assumes a urethral length of 3 cm, which may not be the case in all women, particularly those who have undergone prior surgery for incontinence and/or prolapse.

This study compared the Aa point with the cotton-tipped swab test strain angle in an effort to identify a less invasive, more accurate predictor of urodynamic stress incontinence. The Aa point may approximate the location of the urethrovesical junction and may be helpful in the assessment of anterior vaginal wall prolapse. However, our study did not show it to be a reliable predictor of urodynamic stress urinary incontinence. Although a cotton-tipped swab test straining angle of 30° or greater should not replace multichannel urodynamic testing, this easily performed, widely used office tool was strongly associated with urodynamic stress urinary incontinence.


   Footnotes
 
Received June 21, 2004. Received in revised form August 16, 2004. Accepted August 25, 2004.

doi:10.1097/01.AOG.0000146642.68543.69


   REFERENCES
TOP
ABSTRACT
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
1. Bergman A, Koonings PP, Ballard CA. Negative Q-tip test as a risk factor for failed incontinence surgery in women. J Reprod Med 1989;34:193–7.[Medline]

2. Crystle CD, Charme LS, Copeland WE. Q-tip test in stress urinary incontinence. Obstet Gynecol 1971;38:313–5.[Medline]

3. Bergman A, McCarthy TA, Ballard CA, Yanai J. Role of the Q-tip test in evaluating stress urinary incontinence. J Reprod Med 1987;32:273–5.[Medline]

4. Caputo RM, Benson JT. The Q-tip test and urethrovesical junction mobility. Obstet Gynecol 1993;82:892–6.[Abstract/Free Full Text]

5. Karram MM, Bhatia NN. The Q-tip test: standardization of the technique and its interpretation in women with urinary incontinence. Obstet Gynecol 1988;71:807–11.[Medline]

6. Montz FJ, Stanton SL. Q-tip test in female urinary incontinence. Obstet Gynecol 1986;67:258–60.[Medline]

7. Bump RC, Mattison A, Bo K, Brubaker LP, DeLancey JO, Klarskov P, et al. The standardization of terminology of female pelvic organ prolapse and pelvic floor dysfunction. Am J Obstet Gynecol 1996;175:10–7.[Medline]

8. Montella JM, Ewing S, Cater J. Visual assessment of urethrovesical junction mobility. Int Urogynecol J Pelvic Floor Dysfunct 1997;8:13–7.[Medline]

9. Cogan SL, Weber AM, Hammel JP. Is urethral mobility really being assessed by the pelvic organ prolapse quantification (POP-Q) system? Obstet Gynecol 2002;99:473–6.[Abstract/Free Full Text]

10. Bergman A, Vermesh M, Ballard CA, Platt LD. Role of ultrasound in urinary incontinence evaluation. Urology 1989;33:443–4.[Medline]

11. Kitzmiller JL, Manzer GA, Nebel WA, Lucas WE. Chain cystourethrogram and stress incontinence. Obstet Gynecol 1972;39:333–40.[Abstract/Free Full Text]

12. Kolbl H, Bernaschek G, Wolf G. A comparative study of perineal ultrasound scanning and urethrocystography in patients with genuine stress incontinence. Arch Gynecol Obstet 1988;244:39–45.[Medline]

13. Schaer GN, Koechli OR, Schueeler B, Haller U. Perineal ultrasound for evaluating bladder neck in urinary stress incontinence. Obstet Gynecol 1995;85:220–4.[Abstract]

14. Gordon D, Pearce M, Norton P, Stanton SL. Comparison of ultrasound and lateral chain urethrocystography in the determination of bladder neck descent. Am J Obstet Gynecol 1989;160:182–5.[Medline]

15. Kenton K, Shott S, Brubaker L. Vaginal topography does not correlate well with visceral position in women with pelvic organ prolapse. Int Urogynecol J Pelvic Floor Dysfunct 1997;8:336–9.[Medline]

16. Sze E, Jones W, Ferguson J, Barker C, Dolezal J. Prevalence of urinary incontinence symptoms among black, white, and Hispanic women. Obstet Gynecol 2002;99:572–5.[Abstract/Free Full Text]

17. Grodstein F, Fretts R, Lifford K, Resnick N, Curhan G. Association of age, race, and obstetric history with urinary symptoms among women in the Nurses’ Health Study. Am J Obstet Gynecol 2003;189:428–34.[Medline]

18. Grady D, Brown J, Vintinghoff E, Applegate W, Varner E, Synder T, for the HERS Research Group. Postmenopausal hormones and incontinence: The Heart and Estrogen/Progestin Replacement Study. Obstet Gynecol 2001;97:116–20.[Abstract/Free Full Text]

19. Fantl JA, Bump RC, Robinson D, McClish DK, Wyman JF. Efficacy of estrogen supplementation in treatment of urinary incontinence. Obstet Gynecol 1996;88:745–9.[Abstract]

20. Grodstein F, Lifford K, Resnick N, Curhan G. Postmenopausal hormone therapy and risk of developing urinary incontinence. Obstet Gynecol 2004;103:254–60.[Abstract/Free Full Text]





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