Objective: To examine patient-described experiences of endometriosis diagnosis.

Design: Mixed-methods study.

Setting: Online patient-led endometriosis support groups.

Population or sample: People with endometriosis aged over 18.

Methods: A survey with qualitative and quantitative questions was distributed through online patient-led endometriosis support groups. Descriptive statistics were used to analyse quantitative data, and thematic analysis was used for qualitative responses. Quantitative and qualitative data were triangulated to examine patient experiences of endometriosis diagnosis across age groups.

Main outcome measures: Experiences of endometriosis diagnosis among people with endometriosis.

Results: A total of 2017 people with endometriosis from 63 countries responded to the questionnaire. Patients experienced an average delay of 3.7 years between symptom onset and first presentation of symptoms to a physician (the care-seeking delay) and an average delay of 5.8 years between first presentation of symptoms to a physician and diagnosis of endometriosis (the healthcare-related delay). Patients experienced an average total diagnostic delay of 9.6 years. Participants aged over 35 at the time of the study reported significantly longer times to receive an endometriosis diagnosis (mean 10.7, 95% confidence interval [CI] 10.2-11.2) compared with participants age 18-24 (6.8, 95% CI 6.1-7.5 years). The qualitative analysis identified the following themes: physicians normalised endometriosis symptoms, patients felt their symptoms were ignored by physicians because they were considered unreliable, and participant character attributes (e.g. age, appearance, weight or physical ability) led to clinician dismissal.

Conclusions: People with endometriosis of all age groups reported pervasive negative healthcare experiences during their adolescence. Patients experience delays in seeking care and in receiving a diagnosis once presenting for care.