Efficacy of botulinum toxin A injection in pelvic floor muscles in chronic pelvic pain patients: a study protocol for a multicentre randomised controlled trial

INTRODUCTION: Chronic pelvic pain (CPP) is a common multifactorial condition affecting 6%–27% of women aged 18–50 years worldwide. The aim of this randomised controlled trial (RCT) is to investigate the efficacy and safety of botulinum toxin A (BTA) injection compared with placebo injections in the pelvic floor muscles in women with CPP to improve pain, function and quality of life. METHODS AND ANALYSIS: This is a study protocol for a multicentre, double-blinded placebo controlled RCT conducted in five gynaecology departments across the Netherlands. A total of 94 women over 16 years, with at least 6 months of CPP without anatomical cause and pelvic floor hypertonicity refractory to first-line pelvic floor physical therapy will be included. Participants will be randomised equally to BTA or placebo, both following physical therapy and (re-)education on the pelvic floor at 4, 8, 12 and 26 weeks after intervention. Multiple validated questionnaires focusing on pain, quality of life and sexual function will be collected at baseline and during all follow-up visits. Statistical analysis includes mixed models for repeated measurements. ETHICS AND DISSEMINATION: Ethical approval (NL61409.091.17) was obtained from Radboud University Medical Research Ethics Committee (MREC) and Central Committee on Research involving human Subjects (CCMO). The findings will be presented through international conferences and peer-reviewed scientific journals. TRIAL REGISTRATION NUMBER: EudraCT number (2017-001296-23), CCMO/METC number: NL61409.091.17.