Reliability and Diagnostic Accuracy of a New Vaginal Dynamometer to Measure Pelvic Floor Muscle Strength

Aims Assess the intrarater and interrater reliabilities and diagnostic accuracy of a new vaginal dynamometer to measure pelvic floor muscle (PFM) strength in incontinent and continent women. Methods A test-retest reliability study including 152 female patients. Exclusion criteria: history of urge urinary incontinence, prolapse of pelvic organ, pregnancy, previous urogynecological surgery, severe vaginal atrophy, or neurological conditions. The examination comprised digital assessment using the modified Oxford scale (MOS) and dynamometry measurements with a new prototype hand-held dynamometer. The MOS score ranges from 0 to 5: 0, no contraction; 1, flicker; 2, weak; 3, moderate; 4, good; 5, strong. Examinations were performed by a physiatrist, a physiotherapist and a midwife. The rest period between each rater measurement was 5 minutes. Assessment of intrarater and interrater reliability was calculated with the intraclass correlation coefficient. Results One hundred twenty-two incontinent women and 30 continent women were included. Scores between 0 and 2 in MOS were recorded in 72% of incontinent women versus 20% in continent patients (P< 0.001). Intrarater reliability of the dynamometer was 0.942 (95% confidence interval [CI], 0.920-0.958) and the interrater reliability was 0.937 (95% CI, 0.913-0.954). The analysis of variance analysis showed significant differences in PFM strength across digital assessment categories. The post-hoc analysis showed statistical differences between adjacent categories of MOS 1-2 and 2-3. The diagnostic accuracy showed an area under the curve of 0.82 (95% C,: 0.75-0.89), 0.87 (95% CI, 0.81-0.92), and 0.83 (95% CI, 0.77-0.90) for the physiatrist, midwife, and physiotherapist, respectively. Conclusions The results obtained show a good reliability and validity of this new vaginal dynamometer to quantify PFM strength.