Mary is a 37 year old female who presents with a 5 year history of dysmenorrhoea, deep dyspareunia and chronic pelvic pain. She has regular cycles, usually lasting between 28 to 32 days and denies any intermenstrual or post coital bleeding. She is up to date with her smear tests.
She has been trying to manage her symptoms with simple analgesia but it has not helped. Mary and her husband have also been trying to conceive for the past 18 months but so far have been unsuccessful.
Pelvic and abdominal examinations are unremarkable. What is the most likely diagnosis?