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ORIGINAL RESEARCH |
From the Department of Obstetrics and Gynecology, Medical University of South Carolina, Charleston, South Carolina.
Address reprint requests to: Steven E. Swift, MD, Department of Obstetrics and Gynecology, Medical University of South Carolina, 171 Ashley Avenue, Charleston, SC 29425
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Abstract |
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Methods: This prospective observational study involved 50 women between the ages of 28 and 78 years with primary complaints of urinary incontinence. All subjects underwent a pelvic examination, cystometrogram, and a cough stress test. The cough stress test was performed in the standing position at a bladder volume of 300 mL or at maximum cystometric capacity if it was less than 300 mL. The results of the cough stress test were recorded as positive if urine loss occurred with a cough or as negative if no urine loss was seen and the bladder volume was recorded. The women returned in 1–4 weeks for a second cough stress test performed at the same bladder volume as at the initial examination.
Results: Of the 50 women studied, 45 (90%) had similar results with both cough stress tests. Thirty-five had a positive cough stress test on the initial examination, and 32 of these patients (91%) also had a positive cough stress test at a repeat visit. Fifteen patients had a negative initial cough stress test, and 13 of these 15 (87%) had a negative cough stress test on repeat examination. All 20 patients diagnosed as having pure genuine stress incontinence had a positive cough stress test on initial and repeat examinations. Of the 15 patients diagnosed with detrusor instability or sensory urge incontinence, 13 (86%) had negative cough stress tests on initial and repeat examinations. Of the 15 patients diagnosed with mixed incontinence, 12 (80%) had positive cough stress tests on initial and repeat examinations.
Conclusion: The cough stress test appears to be a reliable test. The reliability is more consistent in women with a diagnosis of pure genuine stress incontinence.
The incidence of urinary incontinence in women has been estimated at 15–30% of the community-dwelling population, and the problem affects more than 50% of all nursing-home residents.1 The two most common forms of urinary incontinence are genuine stress urinary incontinence and detrusor instability, although some women may have mixed incontinence, a combination of the two. One of these two primary forms of incontinence is present in more than 90% of women who complain of urine loss.2
Several studies have demonstrated that the diagnosis of a specific type of incontinence based on a simple history and physical examination is extremely unreliable, and clinical decisions regarding treatment should be based on specialized testing.3–5 Techniques for diagnosing the condition are aimed at detecting stress-induced urine loss or uninhibited bladder contractions. Tests can vary from a simple cough stress test to videocystourethrography, a sophisticated technique that uses multichannel urodynamics and fluoroscopy.
The cough stress test involves filling the patient’s bladder to 300 mL or to subjective fullness, and then, while in an upright position, having the subject perform a series of forceful coughs. The external urethral meatus is observed during the coughs for gross urine loss. If urine loss is noted, the test is positive, and a diagnosis of genuine stress urinary incontinence can be made if the cystometrogram demonstrates a stable bladder. The cough stress test has been compared with other sophisticated testing methods (multichannel urodynamic studies) and has demonstrated good sensitivity and specificity in the diagnosis of genuine stress incontinence.6,7 However, some discrepancy was noted between the diagnoses obtained with multichannel urodynamics and the cough stress test, suggesting that the cough stress test may not be ideal for a screening or diagnostic study. The reason for this may be that the multichannel urodynamic test results are inconsistent or the cough stress test is unreliable.
In our cost-conscious society, having a test that is easy to perform, inexpensive, and also reliably diagnostic would be of great value to physicians managing women with urinary incontinence. As mentioned earlier, the cough stress test has compared favorably with other more sophisticated studies in detecting genuine stress incontinence.6,7 However, the reproducibility of the results of this technique had never been investigated. Therefore, we examined the test-retest reliability of the cough stress test in women presenting for evaluation of urinary incontinence.
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Materials and Methods |
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After providing informed consent, the women underwent a dipstick urinalysis, limited neurologic examination, pelvic examination, single-channel cystometrogram, and a cough stress test as part of their incontinence evaluation. All patients had a negative dipstick urinalysis of a clean-catch urine sample before any testing. The cystometrogram was performed in the standing position with a retrograde fill rate of 100 mL/minute. After completion of the cystometrogram, the patient’s bladder was emptied down to 300 mL (if the maximum tolerated volume was greater than 300 mL) and the catheter was removed. Patients whose maximum cystometric volume was less than 300 mL were emptied down to a bladder volume that they tolerated without undue distress, and the cough stress test was performed at this volume. Patients then placed one foot on the step at the end of the examination table and spread their knees sufficiently to allow visualization of the urethral meatus. They were then instructed to perform three forceful coughs. If the coughs were not deemed to be of maximal effort, the examiner demonstrated a forceful cough for the patient and asked her to repeat the coughs. Any evidence of urine loss concurrent with coughing was noted as a positive result on the cough stress test. If no urine loss was noted, a negative test result was recorded. The results of the examination, cystometrogram maximum volume, the bladder volume at which the cough stress test was performed, and the result of the cough stress test were recorded.
The patients returned to the clinic in 1–4 weeks for a repeat cough stress test. At the return visit, the patient’s bladder was filled in a retrograde fashion through a catheter to the same volume that was recorded at the initial examination. The same examiner performed the initial and follow-up cough stress tests. The examiner was masked to the results of the initial cough stress test at the time that the second test was performed. The cough stress test was performed in an identical fashion to the initial examination. At the time of the catheter placement with either study, the bladder was first emptied and then filled to ensure consistent bladder volumes with both cough stress tests. The final diagnosis was recorded after the first examination and was based on findings from the initial examination only. No treatment was initiated before the follow-up cough stress test.
The diagnosis of pure genuine stress urinary incontinence was made in any patient with a positive cough stress test at the initial examination and a negative preceding cystometrogram. The diagnosis of detrusor instability was made in any patient with detrusor contractions noted on cystometrogram and a negative cough stress test. Sensory urge incontinence was diagnosed in patients with no detrusor contractions on cystometry, but with the subjective statement that they would be leaking during the filling phase of the cystometrogram, and a negative cough stress test. The diagnosis of mixed incontinence was made in patients with a positive cough stress test and uninhibited detrusor contractions on cystometrogram.
A power analysis was performed by ranking the test results, with a positive result ranked as 1 and a negative result ranked as 0. Therefore, with the minimum detectable difference being 1 and with a desired beta of 0.99 and alpha of 0.05, we determined that 50 patients would be necessary. The test-retest reliability of the examination results was evaluated statistically using Kruskal-Wallis one-way analysis of variance on ranks and Dunn method of pairwise multiple comparison between groups.
This study was approved by the Medical University of South Carolina Institutional Review Board for human research. All terminology conforms to that established by the International Continence Society’s Committee on Standardization of Terminology,8 unless otherwise stated.
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Results |
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Of the 50 patients studied, 45 (90%) had a repeat cough stress test result that was consistent with the initial test result. Thirty-five patients had a positive cough stress test on the initial examination, and 32 of these (91%) also had a positive cough stress test at their repeat visit. Fifteen patients had a negative initial cough stress test, and 13 of the 15 (87%) had a negative cough stress test on repeat examination. Only five patients studied had a repeat cough stress test that was inconsistent with the initial cough stress test (three patients had a positive initial test and a negative repeat test, and two patients had a negative initial test and a positive repeat test). A Kruskal-Wallis one-way analysis of variance with pairwise multiple comparison (Dunn method) gave P > .05 for patients with an initial positive cough stress test or an initial negative cough stress test when compared with the results obtained at the follow-up cough stress test. Thus, there was no significant difference between the results of the initial and follow-up cough stress tests, suggesting that this is a highly reliable test for a positive or negative result.
The results were then broken down by diagnosis (Table 1
). All 20 patients diagnosed with genuine stress incontinence had a positive cough stress test on both the initial and repeat examinations. Of the 15 patients diagnosed with detrusor instability or sensory urge incontinence, 13 (86%) had negative cough stress tests on both initial and repeat testing. Of the 15 patients diagnosed with mixed incontinence, 12 (80%) had a positive cough stress test on both the initial and repeat examinations.
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Discussion |
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The problems with multichannel studies may account for some of the differences between cough stress test results with the uninstrumented urethra and the results obtained during multichannel urodynamic testing. Conversely, the discrepancies may stem from poor reliability or inconsistent results of the cough stress test. To our knowledge, the reliability of the cough stress test has not been determined previously. The results of our study showed that 90% of the subjects had consistent cough stress test results upon repeat testing, and the reliability was further improved (100%) in women with a diagnosis of pure genuine stress incontinence.
When the cystometrogram preceding the cough stress test is positive for uninhibited detrusor contractions, the sensitivity of the cough stress test falls to 77%.6 In this setting, the results of the cough stress test are unreliable because uninhibited detrusor contractions may be initiated by a cough, and urine loss during ensuing coughs may be the result of the detrusor contraction and not the result of a defective urethral-closure mechanism. This was borne out in our data, which showed that the reproducibility of the cough stress test was least consistent (80%) in women with mixed incontinence. In this setting, a positive cough stress test may simply reflect uninhibited detrusor contractions in up to 20% of subjects, and therefore should not be relied upon. In patients suspected of having mixed incontinence, a multichannel urodynamic cough urethral pressure profile should be done to confirm the presence of genuine stress incontinence.
Five women in this study had inconsistent test results. Three women diagnosed with mixed incontinence had an initial positive cough stress test that was negative on repeat testing. We did not repeat a formal cystometrogram when patients returned for their follow-up cough stress test. If this had been done and no uninhibited detrusor contractions were noted on repeat testing, then the discrepancy in test results could be explained. However, these patients may have had pure detrusor instability and no component of genuine stress incontinence. Two of these women were diagnosed with detrusor instability and initially had a negative cough stress test that became positive on repeat testing. This, likewise, may represent the presence of uninhibited detrusor contractions that were the cause of the positive results on the follow-up cough stress test. What occurred in those women who had discrepancies in their cough stress test results remains speculative. However, they all had one thing in common: uninhibited detrusor activity. Therefore, in the presence of uninhibited detrusor contractions, the cough stress test results have less reliability.
The cough stress test is a useful and reliable tool in the diagnosis of genuine stress urinary incontinence, but it still must be used in conjunction with other urodynamic testing for complete evaluation of incontinent women, particularly if detrusor instability is suspected.
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Footnotes |
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Received September 28, 1998. Received in revised form January 25, 1999. Accepted February 3, 1999.
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References |
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2. Makinen JI, Gronroos M, Kiilholma PJA, Tenho TT, Pirhonen JP, Erkkola RU. The prevalence of urinary incontinence in a randomized population of 5247 adult Finnish women. Int Urogynecol J 1992;3:110–3.
3. Summitt RL, Stoval TG, Bent AE, Ostergard DR. Urinary incontinence: Correlation of history and brief office evaluation with multichannel urodynamic testing. Am J Obstet Gynecol 1992;166:1835–45.[Medline]
4. Walters MD, Shields LE. The diagnostic value of history, physical examination, and the Q-tip cotton swab test in women with urinary incontinence. Am J Obstet Gynecol 1988;159:145–9.[Medline]
5. Sand PK, Hill RC, Ostergard DR. Incontinence history as a predictor of detrusor stability. Obstet Gynecol 1993;71:257–60.
6. Swift SE, Ostergard DR. Evaluation of current urodynamic test methods in the diagnosis of genuine stress incontinence. Obstet Gynecol 1995;86:85–91.[Abstract]
7. Scotti RJ, Myers DL. A comparison of the cough stress test and single channel cystometry with multichannel urodynamic evaluation in genuine stress incontinence. Obstet Gynecol 1993;81:430–3.[Abstract]
8. Abrams P, Blavis JG, Stanton SL, Anderson JT. ICS Committee on Standardization of Terminology. The standardization of terminology of lower urinary tract function recommended by the International Continence Society. Int Urogynecol J 1990;1:45–58.
9. Miklos JR, Sze EH, Karram MN. A critical appraisal of the methods of measuring leak point pressures in women with stress incontinence. Obstet Gynecol 1995;86:349–52.[Abstract]
This article has been cited by other articles:
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  J. M. Holroyd-Leduc, C. Tannenbaum, K. E. Thorpe, and S. E. Straus What Type of Urinary Incontinence Does This Woman Have? JAMA, March 26, 2008; 299(12): 1446 - 1456. [Abstract] [Full Text] [PDF]
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