Hormonal Treatment for Pain from Rectovaginal Endometriosis Surgical treatment may reduce the pain associated with rectovaginal endometriosis, but it is associated with a high risk of morbidity and major complications. The effect of medical treatment in terms of pain relief in women with rectovaginal endometriosis appears to be substantial (357). In a systematic review including 217 cases of medically treated rectovaginal endometriosis, the antalgic effect of the considered medical therapies (vaginal danazol, GnRH agonist, progestin, and estrogen-progestin combinations used transvaginally, transdermally, or orally) for the entire treatment period (from 6 to 12 months) was 60% to 90%, with patients reporting considerable reduction or complete relief from pain symptoms, with the exception of when an aromatase inhibitor was used alone (357).
Oral Contraceptives Although oral contraceptives are effective in inducing a decidualized endometrium, the estrogenic component in oral contraceptives may stimulate endometrial growth and increase pelvic pain in the first few weeks of treatment. The long-term significance of this effect is undetermined. Oral contraceptives are less costly than other treatments and may be helpful in the short-term management of endometriosis with potential long-term benefits in some women.
The use of cyclic oral contraceptives may provide prophylaxis against the development or recurrence of endometriosis. Estrogens in oral contraceptives may stimulate the proliferation of endometriosis. The reduced menstrual bleeding that often occurs in women taking oral contraceptives may be beneficial to women with prolonged, frequent menstrual bleeding, which is a known risk factor for endometriosis (45).
Further research is warranted to assess the effect of low-dose oral contraceptives in preventing endometriosis and treating associated pain, because the evidence for its efficacy is limited. In a systematic review to assess the effects of OC’s in comparison to other treatments for painful symptoms of endometriosis in women of reproductive age, only one study met the inclusion criteria (all truly randomized controlled trials of the use of OCs in the treatment of women of reproductive age with symptoms ascribed to the diagnosis of endometriosis and made visually at surgical procedure were included) (358,359). In this study, a total of 57 women were allocated to two groups to compare an OC to a GnRH analogue (359). Methods of randomization and allocation concealment were unclear and the analogue group became amenorrheic during the treatment period of 6 months, while women in the OC group reported a decrease in dysmenorrhea (358,359). No evidence of a significant difference between the two groups was observed in terms of dysmenorrhea at 6 months follow-up after stopping treatment (OR 0.48; 95% CI, 0.08–2.90). Some evidence for a decrease in dyspareunia was found at the end of treatment in women in the GnRH analogue group; although no evidence of a significant difference in dyspareunia was observed at the end of the 6 months follow-up (OR 4.87; 95% CI, 0.96–24.65). According to these data, there is no evidence of a difference in outcomes between the OC studied and GnRH analogue in the treatment of endometriosis-associated painful symptoms (358). The lack of studies with larger sample sizes or studies focusing on other comparable treatments is concerning, and further research is needed to evaluate the role of OCs in managing symptoms associated with management of endometriosis (358).