Medical treatment for rectovaginal endometriosis: what is the evidence?

Rectovaginal endometriosis usually causes distressing pain. Surgical treatment may be effective but is associated with a high risk of morbidity and major complications. Information on the effect of medical alternatives for pain relief in this condition is scarce. A comprehensive literature search was conducted to identify all the English language published observational and randomized studies evaluating the efficacy of medical treatments on pain associated with rectovaginal endometriosis. A combination of keywords was used to identify relevant citations in PubMed, MEDLINE and EMBASE. A total of 217 cases of medically treated rectovaginal endometriosis were found; 68 in five observational, non-comparative studies, 59 in one patient preference cohort study, and 90 in a randomized controlled trial. An aromatase inhibitor was used in two of the non-comparative studies, vaginal danazol in one, a GnRH agonist in one, and an intrauterine progestin in one. Two estrogen-progestin combinations used transvaginally or transdermally were evaluated in the patient preference study, whereas an oral progestin and an estrogen-progestin combination were compared in the randomized controlled trial. With the exception of an aromatase inhibitor used alone, the antalgic effect of the considered medical therapies was high for the entire treatment period (from 6 to 12 months), with 60-90% of patients reporting considerable reduction or complete relief from pain symptoms. Despite problems in interpretation of data, the effect of medical treatment in terms of pain relief in women with rectovaginal endometriosis appear substantial.