Objective: To explore the characteristics of symptom flares, and individual experiences and behaviours during flares in people with endometriosis. Design: Online questionnaire shared on patient support sites. Setting: People with a confirmed or working diagnosis of endometriosis. Population or Sample: A total of 236 responses were collected. Methods: Descriptive and comparative analysis of quantitative data, and thematic analysis of qualitative data. Main Outcome Measures: The characteristics, triggers, treatments and strategies for symptom flares as well as perceived predictability and self-efficacy in relation to flares, reasons for lack of healthcare access during flare, where advice on flares was received and quality-of-life. Results: We identified a wide variation in the characteristics of flares and of treatments/strategies for prevention. Participants reported low flare self-efficacy and low perceived predictability of flares. Only 35.3% reported receiving advice from a healthcare provider about flares. We developed 5 themes to suggest why participants did not contact healthcare provider: ‘what can they do?’, ‘I can cope, it will end’, ‘broken healthcare system’, ‘perceived dismissal and gaslighting’ and ‘symptoms stop me’. Conclusions: Flares have a large impact on quality-of-life and are clinically very important. Individuals do not commonly receive advice from healthcare providers or contact healthcare providers during a flare. More research is needed to identify mechanisms underlying flares, as well as developing and disseminating management tools to prevent, manage and treat flares.

Objective: To investigate the prevalence and experience of symptom flares in women with Chronic Pelvic Pain (CPP) as well as their triggers Design: Cross-sectional questionnaire within the Translational Research in Pelvic Pain clinical cohort study. Setting: Women with CPP, with subgroups of women with endometriosis (EAP), interstitial cystitis/bladder pain syndrome (BPS), comorbid endometriosis and interstitial cystitis/bladder pain syndrome (EABP), and those with pelvic pain without endometriosis or interstitial cystitis/bladder pain syndrome (PP). Population or sample: 100 participants across subgroups. Methods: Questionnaire within large cohort study. Main Outcome Measures: The prevalence and characteristics of short, medium and long symptom flares in CPP. Results: 76% of women with CPP experience symptom flares of at least one length (short, medium and/or long). Flares are associated with painful and non-painful symptoms. There is large variation amongst those with CPP for the frequency, duration, symptoms and triggers for these flares. Participants reported flares as stopping them from doing things they would usually do, participants thinking about symptoms of flares as well as flares being bothersome. Conclusions: Flares are prevalent and clinically very important in the context of CPP. More research is needed to elucidate the mechanisms and characteristics underlying flares. Clinical practice should include an enquiry of flares with the aim of finding strategies to lessen their burden. Funding: This project has received funding from the Innovative Medicines Initiative 2 Joint Undertaking under grant agreement No 777500. This Joint Undertaking receives support from the European Union’s Horizon 2020 research and innovation programme and EFPIA Companies.