The Reliability of Performing a Screening Cystometrogram Using a Fetal Monitoring Device for the Detection of Detrusor Instability

Objective: To determine if a cystometrogram performed using the intrauterine pressure channel of a fetal monitor can be used to screen for detrusor instability in women undergoing evaluation for urinary incontinence. Methods: Sixty-six women with primary complaints of urinary incontinence were randomized to have a cystometrogram performed at their initial visit with a multichannel electronic cystometer or with the intrauterine pressure channel of a fetal monitor. Subjects underwent a second cystometrogram 1–4 weeks later with the alternative technique. The results were analyzed with χ 2 analysis and correlation coefficients. Results: Twenty-two subjects had detrusor instability diagnosed by the multichannel electronic cystometer. The fetal monitor cystometrogram was 91% sensitive and 86% specific in detecting detrusor instability, and had a 77% positive predictive value and a 95% negative predictive value. The correlation coefficients between the two examinations for bladder volume at first sensation, maximum capacity, volume at first contraction, and intensity of uninhibited detrusor contraction were r = 0.51, r = 0.69, r = 0.87, and r = 0.79, respectively; all of these were statistically significant. Conclusion: The intrauterine pressure channel of a fetal monitor can be used reliably to perform a cystometrogram to screen for detrusor instability in patients presenting with complaints of urinary incontinence.