Stress urinary incontinence is a prevalent condition that significantly impairs the quality of life. This article presents a critical summary of the current literature on the use and value of urodynamic studies in the evaluation of stress urinary incontinence in women.
Key points
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Surgical treatment of stress urinary incontinence with retropubic or transobturator midurethral slings offers excellent results with a low risk of adverse events.
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Urodynamics are prudent when the diagnosis of stress urinary incontinence is not confirmed by other investigations or when prior surgical intervention has failed.
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Two recent noninferiority randomized controlled trials did not demonstrate a significant difference in objective and subjective treatment outcome following stress urinary incontinence surgery between women who had a preoperative office evaluation or urodynamic studies.
Urinary incontinence is defined as the “complaint of involuntary loss of urine”. Several types of urinary incontinence have been described that may require different treatment approaches. The prevalence of urinary incontinence in women older than 20 years is 25% and increases with age. Half of incontinent women experience stress incontinence alone, and 36% have mixed incontinence. Stress urinary incontinence (SUI) is defined as the “complaint of involuntary loss of urine on effort or physical exertion, or on sneezing and coughing”. The diagnosis of SUI in women is based on symptoms and signs as demonstrated on the physical examination or on urodynamic observation in the absence of a detrusor contraction. Stress incontinence may also be diagnosed in the presence of other conditions, such as urinary frequency, urgency, nocturia, or voiding difficulty. Other types of urinary incontinence can coexist with SUI, such as urgency urinary incontinence (UUI), mixed urinary incontinence (MUI), or nocturnal enuresis.
Cost of urodynamic studies
The goal of urodynamic studies (UDS) in women with SUI is to objectively demonstrate the type of urinary incontinence and exclude other diagnoses. Therefore, this assessment may be helpful when the benefits outweigh the costs. The main benefits would be to improve patient outcomes (ie, cure the urinary incontinence) and prevent any adverse events. The costs are related to the invasive nature of the test. It can cause patient embarrassment, pain during and after the test, and urinary tract infections. UDS are expensive, time-consuming evaluations, with costs that vary according to health care systems. A cost-effectiveness study demonstrated that a basic office evaluation was less costly to cure incontinence in a population with highly prevalent SUI-only patients. A decision analysis model demonstrated that immediate sling placement for women with pure SUI or MUI was less costly and more effective than basing the treatment decision on the UDS finding. UDS interpretation is subjected to variable reliability and quality, as it is highly operator dependent. Urodynamic testing has the risk of false positives from a series of physiologic and equipment artifacts, which include straining, rectal contraction, or poor pressure transmission. On the other hand, it can result in false negatives if it does not reproduce the patients’ symptoms. For instance, 10% to 18% of asymptomatic volunteers have uninhibited detrusor contractions on the urodynamic evaluation; up to 40% of patients with urge incontinence do not show detrusor overactivity on cystometrogram.
Cost of urodynamic studies
The goal of urodynamic studies (UDS) in women with SUI is to objectively demonstrate the type of urinary incontinence and exclude other diagnoses. Therefore, this assessment may be helpful when the benefits outweigh the costs. The main benefits would be to improve patient outcomes (ie, cure the urinary incontinence) and prevent any adverse events. The costs are related to the invasive nature of the test. It can cause patient embarrassment, pain during and after the test, and urinary tract infections. UDS are expensive, time-consuming evaluations, with costs that vary according to health care systems. A cost-effectiveness study demonstrated that a basic office evaluation was less costly to cure incontinence in a population with highly prevalent SUI-only patients. A decision analysis model demonstrated that immediate sling placement for women with pure SUI or MUI was less costly and more effective than basing the treatment decision on the UDS finding. UDS interpretation is subjected to variable reliability and quality, as it is highly operator dependent. Urodynamic testing has the risk of false positives from a series of physiologic and equipment artifacts, which include straining, rectal contraction, or poor pressure transmission. On the other hand, it can result in false negatives if it does not reproduce the patients’ symptoms. For instance, 10% to 18% of asymptomatic volunteers have uninhibited detrusor contractions on the urodynamic evaluation; up to 40% of patients with urge incontinence do not show detrusor overactivity on cystometrogram.
Urodynamic evaluation
UDS can describe a series of different physiologic tests but most commonly refers to the more complete assessment of multichannel cystometry. Simultaneous recording of intravesical and intra-abdominal pressure allows an assessment of bladder sensation, capacity, and compliance, along with the voiding pattern.
Urethral function in a setting of clinical SUI can be better understood during cystometry. It can show a normal urethral closure mechanism or an incompetent one with either urethral relaxation incontinence (leakage in the absence of raised abdominal pressure) or urodynamic stress incontinence (with an increased intra-abdominal pressure). The urethral pressure profile can also be measured along with leak point pressures. The abdominal leak point pressure (ALPP) or the Valsalva leak point pressure (VLPP) is particularly of interest in the urodynamic assessment of SUI, as it establishes the lowest intravesical pressure required to provoke urinary leakage per urethra in the absence of a detrusor contraction ( Fig. 1 ).
