Effect of menstrual cycle phase and hormonal treatments on evaluation of tubal patency in baboons

Background: We evaluated whether menstrual cycle phase influences the assessment of tubal patency by hysterosalpingography (HSG) in baboons. Methods: Retrospective analysis of baseline tubal patency studies and serum estradiol (E₂) and progesterone (P4) values obtained from female baboons used as models for development of non-surgical permanent contraception in women. The main outcome measure was bilateral tubal patency (BTP) in relationship with estradiol level. Results: Female baboons (n = 110) underwent a single (n = 81), two (n = 26), or three (n = 3) HSG examinations. In 33/142 (23%) HSG examinations, one or both tubes showed functional occlusion (FO). The median E₂ in studies with BTP (49 pg/mL) was significantly higher than in those studies with FO (32 pg/mL, P =.005). Among 18 animals with repeat examinations where serum E₂ changed from <60 to ≥ 60 pg/mL, 13 results changed from FO to BTP (P =.0001). No sets showed a change from BTP to FO with an increase in estradiol. Conclusion: In baboons, functional occlusion of the fallopian tube is associated with low estradiol levels, supporting a role for estrogen-mediated relaxation of the utero-tubal junction.