Diagnostic accuracy of alpha and beta angles measured by transperineal ultrasound for stress urinary incontinence: a meta-analysis

Stress urinary incontinence (SUI) is a common condition among women that significantly impacts their quality of life. Transperineal ultrasound has emerged as a non-invasive diagnostic modality for assessing pelvic floor dysfunction in SUI, with alpha and beta angles proposed as potential markers of urethral and bladder neck mobility. However, variability in findings across studies necessitates a comprehensive evaluation of their diagnostic utility. This meta-analysis aimed to synthesize evidence on the diagnostic accuracy of alpha and beta angles measured by transperineal ultrasound in differentiating women with SUI from controls. A systematic search of PubMed, Embase, Cochrane Library, and Scopus was conducted to identify relevant studies. Nine studies with 1,157 participants (584 with SUI and 573 controls) were included. The pooled mean differences in alpha and beta angles between SUI and control groups were calculated using a random-effects model. Heterogeneity was assessed using the I² statistic, and potential publication bias was evaluated through funnel plot analysis. The pooled mean alpha angle was significantly larger in the SUI group, with a mean difference of 15.77° (95% CI: 9.62, 21.91; I²=93%), indicating altered urethral mobility during the Valsalva maneuver. Similarly, the pooled mean beta angle was significantly higher in the SUI group, with a mean difference of 21.18° (95% CI: 12.11, 30.25; I²=95%), reflecting greater bladder neck descent. Despite substantial heterogeneity, the findings consistently support the diagnostic value of these ultrasound parameters. In conclusion, alpha and beta angles measured via transperineal ultrasound are significantly larger in women with SUI, highlighting their potential as non-invasive markers for pelvic floor dysfunction. However, variability in imaging protocols and patient characteristics underscores the need for standardization to enhance diagnostic accuracy. These findings support the incorporation of ultrasound measurements into clinical assessments for SUI.