Journal of the Medical Association of Thailand Vol 98, No 3:MARCH 2015 0125-2208 98 3 2015 Mar Development of a Pelvic Floor Muscle Strength Evaluation Device 219 EN Jittima Manonai Sakuntala Kamthaworn Kuson Petsarb Rujira Wattanayingcharoenchai Original Article To validate the device and investigate the effect of this device on symptoms, quality of life, and pelvic floor muscle strength. The device was designed to measure vaginal pressure changes using air-pressure balloon and abdominal wall muscle activities using surface electromyography. To test the accuracy of the device, for vaginal pressure measurement, a Mercury sphygmomanometer was used as a gold standard, and for abdominal wall muscle activity, a standard biofeedback machine was used as a reference device. A randomized, controlled trial was conducted in sixty-one women with stress urinary incontinence. They were randomly divided into two groups undergoing PFMT with a single 15-minute biofeedback session (BF + PFMT group) or without biofeedback (PFMT group). The pelvic floor muscle strength, abdominal wall muscle activity and incontinence-specific quality of life questionnaire (I-QOL), measurements were evaluated at baseline and at 8- and 16-week after treatment. The accuracy of vaginal probe pressure perineometry was 98% compared to a standard sphygmomanometer. The device could detect abdominal wall muscles activities at 10 milliseconds (100 Hz), 20 milliseconds (50 Hz), and 50 milliseconds (20 Hz). After 8 and 16 weeks of treatment, there were statistically significant intra-group differences in the maximum vaginal squeeze pressure in both groups. However, the inter-group differences were not demonstrated. The proportion of women who performed pelvic floor muscle exercise correctly was significantly higher in the BF + PFMT group (72.41%) compared to the PFMT group (21.88%) at week 16 (p<0.05). The simple pelvic floor muscle strength evaluation device might be helpful in pelvic floor muscle training in a low resource setting. Device Pelvic floor muscle Quality of life Stress urinary incontinence Biofeedback