Examining the Evidence
Q Is urodynamic testing reliable?
<huc>A</huc> Yes and no. For stress urinary incontinence, there was substantial reliability and interobserver consistency in interpretations of urodynamic tests.
However, reliability was only moderate for diagnoses of detrusor overactivity, and interobserver consistency was only fair. Thus, urodynamic testing may not be as informative for this diagnosis.
Urodynamic testing has traditionally been used to evaluate and distinguish between different types of urinary incontinence. Weidner and colleagues1 demonstrated that subjective symptoms may not always predict the ultimate diagnosis and recommended urodynamic evaluation prior to initiation of therapy or surgical intervention.
Urodynamic testing is not without limitations:
Interobserver agreement was moderate
METHODS Six physicians reviewed the records (ie, blinded study packets that retained key portions of the patient’s history and urodynamic findings) of 100 women who presented to a urogynecology or female urology practice and were referred for urodynamic testing. The 6 physician reviewers assigned both clinical and International Continence Society diagnoses to each record and reviewed the packets again at least 4 months later.
RESULTS Reviewers were consistent in their own evaluations of urodynamic tracings and diagnoses. Nor was there much intra-observer difference between female urologists and urogynecologists.
However, interobserver agreement varied with the diagnosis, and also was lower when a particular sign or symptom was present, suggesting that the absence of symptoms and signs was used to rule out diagnoses, as opposed to ruling them in.
Detrusor overactivity a more elusive diagnosis?
These results are consistent with earlier studies that showed stress incontinence to be more reliably diagnosed on both simple cystometry and multichannel cystometry, and which showed that symptoms alone are not a sufficient basis for surgical management.
However, the interpretation of detrusor overactivity appears to be less reliable and less consistent. The demonstration of urge incontinence with office cystometry has been shown to predict detrusor overactivity, but its absence does not preclude this diagnosis.4
Urodynamic testing is most useful for diagnosing stress incontinence
This study occurred at a single institution without standardized guidelines for interpretation of urodynamic test results. A multicenter study by Zimmern et al5 for the Urinary Incontinence and Treatment Network demonstrated excellent inter-rater reliability for urodynamics between both central and local-site reviewers—after establishing uniform certification standards.
Thus, it seems clear that standardized guidelines and modules would assist in the interpretation of urodynamic tests. Until then, urodynamic testing should entail a concerted effort to standardize the interpretation of urodynamic diagnoses.
1. Weidner AC, Myers ER, Visco AG, Cundiff GW, Bump RC. Which women with stress incontinence require urodynamic evaluation? Am J Obstet Gynecol. 2001;184:20-27.
2. Weber AM, Taylor RJ, Wei JT, et al. The cost-effectiveness of preoperative testing (basic office assessment vs urodynamics) for stress urinary incontinence in women. BJU Int. 2002;89:356-363.
3. Weber AM, Walters MD. Cost-effectiveness of urodynamic testing before surgery for women with pelvic organ prolapse and stress urinary incontinence. Am J Obstet Gynecol. 2000;183:1338-1347.
4. Wall LL, Wiskind AK, Taylor PA. Simple bladder filling with a cough stress test compared with subtracted cystometry for the diagnosis of urinary incontinence. Am J Obstet Gynecol. 1994;171:1472-1479.
5. Zimmern P, Nager CW, Albo M, Fitzgerald MP, McDermott S. For the Urinary Incontinence Treatment Network. Interrater reliability of filling cystometrogram interpretation in a multicenter study. J Urol. 2006;175:2174-2177.