Purpose: This study was undertaken to evaluate the effects of a subdermal implant containing nomegestrol acetate (Uniplant) on endometrial histology and ovarian function.
Methods: Twenty healthy female volunteers of reproductive age were included and completed a menstrual diary throughout the study. Hysteroscopy, transvaginal sonography and blood sampling were performed prior to implant insertion (control cycle) and following 6 and 12 months of Uniplant use. Transvaginal sonography was performed every other day from Day 8 of the cycle up to the obtainment of sonographic evidence of a 12-mm follicle, then every day until the obtainment of sonographic evidence of follicular rupture and thereafter every other day until the next menstrual bleeding. Blood samples were taken for the measurement of estradiol, follicle-stimulating hormone, luteinizing hormone and progesterone on the same days on which transvaginal sonography was performed. The implants were removed after 1 year.
Results: Twenty percent of cycles were ovulatory, and 80% were anovulatory. The development of persistent nonluteinized follicle occurred in 40% of all cycles studied, inadequate luteal phase occurred in 20% of cycles and no follicular development occurred in 40%. Endometrial thickness remained below 8 mm in all cycles studied. Alterations in endometrial vascularization were observed in all treated cycles.
Conclusion: Our results suggest that this long-acting contraceptive method affects follicular growth and endometrial vascularization, disrupts endometrial architecture and leads to inadequate luteal phase.