Presence And Laterality Of Endometriosis In Adolescent Patients With Obstructed Müllerian Duct Anomalies, A Twenty-Three Year Retrospective Cohort Analysis Between 2002 – 2025 At An Australian Quaternary Paediatric And Adolescent Gynaecology Service

STUDY OBJECTIVE: To determine the prevalence and laterality of endometriosis in adolescents with obstructed Müllerian duct anomalies (MDAs). METHODS: A retrospective cohort study of 42 adolescents with surgically confirmed obstructive MDAs managed at a quaternary Paediatric and Adolescent Gynaecology Service between 2002 and 2025. All patients underwent laparoscopy or laparotomy during surgical correction of obstructed MDAs and visual inspection for endometriosis. Lesion laterality and location were assessed relative to the side of the outlet obstruction. Demographic, clinical, and surgical data were collected from the medical records. RESULTS: Endometriosis was visually confirmed at surgery in 74% (31/42) of cases. Lesions occurred on the same side(s) as the outlet obstruction in 97% of affected cases (30/31), making the role of chance extremely unlikely. CONCLUSION: Endometriosis is highly prevalent among adolescents with obstructed MDAs, and lesions predominantly occurred on the side(s) of the obstruction. These findings strengthen the evidence supporting retrograde menstruation as a key driver for endometriosis pathogenesis in this cohort.