A patient presents to you with pain and swelling in the vagina. On examination you find a bluish bulge on the posterior vaginal wall behind the cervix. The history reveals that the swelling enlarges and becomes more painful with approaching menses. What is your diagnosis?

Ganer's duct cyst arises from the remnants of mesonephric duct and lies on the anterolateral aspect of vaginal wall. It is often asymptomatic. Baholin's cyst protrudes into the lower pa of vagina and becomes painful when infected. Endometriotic cyst may be bluish in colour with increase in pain and size near menses. A biopsy is confirmative and treatment is excision or suppression of menstruation. Ref: Shaw's Textbook of Gynecology, Page - 104