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Am Fam Physician. 2008;78(11):online

Background: Urinary incontinence is a common condition, with an overall prevalence of 17 to 55 percent in older women and 12 to 42 percent in younger to middle-aged women. It can be categorized as stress, urge, mixed, overflow, or functional. Stress incontinence occurs when effort, exertion, sneezing, or coughing results in leakage. Urge incontinence, resulting from detrusor overactivity, is indicated by a sudden urge to void with concomitant leakage. Mixed incontinence is a combination of stress and urge incontinence. Overflow incontinence is associated with overdistension of the bladder caused by a neurologic condition or obstruction. Functional incontinence stems from the inability to reach the toilet in time, usually because of cognitive or mobility problems. Stress incontinence is more likely to affect younger women, whereas urge incontinence predominates in older age. Holroyd-Leduc and colleagues sought to determine which diagnostic approach was most accurate in determining the type of urinary incontinence.

The Study: The authors performed a search of Medline and EMBASE. Studies had to use an accepted reference standard for categorizing types of urinary incontinence. Calculations were performed to determine study heterogeneity and likelihood ratios (LRs). Of 202 articles pulled from an initial pool of 1,896 citations and 38 additional references, 40 articles met inclusion criteria. The presence of coughing, sneezing, lifting, walking or running as initiators of incontinence increased the likelihood of stress incontinence (LR = 2.2; 95% confidence interval [CI], 1.6 to 3.2), and their absence decreased the likelihood (LR = 0.39; 95% CI, 0.25 to 0.61).

With urge incontinence, a positive response to the question, “Do you experience such a sudden and strong urge to void that you leak before reaching the toilet?” increased the likelihood of urge incontinence (LR = 4.2; 95% CI, 2.3 to 7.6), and a negative response decreased the likelihood (LR = 0.48; 95% CI, 0.36 to 0.62). The presence of symptoms of urinary frequency and urgency with or without urge incontinence increased the likelihood of detrusor overactivity (LR = 2.1; 95% CI, 1.8 to 2.3), but the absence of these symptoms did not affect the likelihood (LR = 0.83; 95% CI, 0.81 to 0.86).

Regarding physical examination findings, some maneuvers appear to be diagnostically useful. The stress test involves observing the patient for urinary leakage while coughing or with increased abdominal pressure. A positive stress test increases the likelihood of stress incontinence (LR = 3.1; 95% CI, 1.7 to 5.5). A positive filled-bladder stress test (LR = 9.4; 95% CI, 1.1 to 77.7) may be more accurate than a positive empty-bladder stress test (LR = 2.8; 95% CI, 1.3 to 1.5). A negative filled-bladder stress test is better than a negative empty-bladder stress test at identifying women who probably do not have stress incontinence (LR = 0.07; 95% CI, 0.01 to 0.39 versus LR = 0.48; 95% CI, 0.34 to 0.68, respectively). In a variant of the stress test, having a woman just cough to observe leakage or urine is also helpful in identifying women with stress incontinence if the test is positive, and without stress incontinence if it is negative.

The cotton swab test consists of placing a cotton swab in the patient's urethra to see if there is any angle change with cough. A positive result does not increase the likelihood of stress incontinence (LR = 1.38; 95% CI, 0.91 to 2.09), but a normal result does decrease the likelihood (LR = 0.41; 95% CI, 0.22 to 0.76). The pad test (weighing continence pads) increases the likelihood of incontinence if positive (LR = 3.3; 95% CI, 2.0 to 5.4), and helps rule out incontinence if negative (LR = 0.11; 95% CI, 0.05 to 0.27). However, the pad test does not specifically distinguish between incontinence types. Although measurement of postvoid residual urine volume has not been studied in distinguishing incontinence types, it is common practice to check for inadequate bladder emptying, especially in the setting of overflow or urge incontinence.

This study also evaluated the value of a comprehensive clinical assessment, consisting of a history, physical examination, and urodynamic studies, in diagnosing urinary incontinence. These types of assessments were helpful in confirming a diagnosis of stress incontinence (positive LR = 3.7; 95% CI, 2.6 to 5.2; negative LR = 0.20; 95% CI, 0.08 to 0.51), but less so in diagnosing urge incontinence (positive LR = 2.2; 95% CI, 0.55 to 8.7; negative LR = 0.63; 95% CI, 0.34 to 1.17). One study involving comprehensive evaluation by a nurse practitioner did appear to help confirm the diagnosis of urge incontinence in older women. See the accompanying table for a summary of diagnostic approaches.

Diagnostic approachComments
Patient history (coughing, sneezing, lifting, walking, running as initiators of incontinence)Most useful for diagnosing stress incontinence
Comprehensive history, physical examination, urodynamic studiesMost useful for diagnosing stress incontinence
Filled-bladder stress test (cough, Valsalva maneuver with bladder filled with saline)Most useful for diagnosing stress incontinence
Empty-bladder stress test (cough, Valsalva maneuver with empty bladder)Somewhat useful for diagnosing stress incontinence
Cotton swab testNot useful for diagnosing stress incontinence
Leakage in conjunction with voiding urgeUseful for diagnosing urge incontinence
Pad test (weighing continence pads)Useful for confirming incontinence
Postvoid residual urine volumeIdentifies inadequate emptying, but unproved usefulness in distinguishing types of urinary incontinence

Conclusion: The authors conclude that when evaluating women with urinary incontinence, a comprehensive approach is a reliable method of classifying the type of incontinence. Urge incontinence is diagnosed when the patient describes having urine loss in the context of an urge to void. Filled-bladder stress tests are useful for diagnosing stress incontinence.

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