Endometriosis: the consequence of uterine denervation-reinnervation.

Difficult intrapartum episodes and persistent straining during defecation cause injuries to uterine nerves and uterosacral ligaments. Injuries to uterine nerves (denervation) result in loss of fundocervical polarity, uterotubal dysmotility and retrograde menstruation. Ectopic endometrium, delivered by retrograde menstruation, adheres to injuries to uterosacral ligaments and peritoneal surfaces. Difficult vaginal deliveries result in laparoscopic appearances of asymmetry of uterosacral ligaments with, or without, ectopic endometrium. Straining during defaecation causes the "classic" appearances of nulliparous endometriosis including hypertrophy of the uterosacral ligaments often with large volumes of ectopic endometrium. Laparoscopic appearances depend on the site, nature, extent, and timing of tissue injury, as well as the presence of available endometrium. Tissue repair, including reinnervation in the uterine isthmus, cervix, vagina and uterosacral ligaments, contributes to chronic pelvic pain, dysmenorrhea, dyspareunia and subfertility some time after the primary injuries.