Temporal relationship between Uniplant insertion and changes in cervical mucus.

This study was undertaken to determine the time required by a single implant containing nomegestrol acetate to affect cervical mucus production and sperm penetration in women. All subjects were investigated and, if necessary, treated for any kind of cervicitis or vaginitis prior to starting cervical mucus study. The subjects had not used hormonal contraception for at least three months prior to investigation. They were counseled to use condoms during this study and also to refrain from intercourse during the period of cervical mucus sampling. Follicular development and endometrial thickness were analyzed by transvaginal sonography. Cervical mucus examination, sperm penetration test, and transvaginal sonography were performed during the control cycle and during the first cycle of Uniplant use. Blood samples were taken for the measurement of estradiol, LH, and progesterone. Cervical mucus and sperm penetration tests were evaluated according to the World Health Organization (WHO) criteria. In the treated cycle, when cervical mucus reached a score of 8-10, Uniplant was inserted, independent of the day of the cycle. Cervical mucus was then collected at 0, 4, 8, 12, 24, 48, and 96 h later until a marked change in volume, consistency, ferning spinnbarkheit, and cellularity was observed. All samples were also used for sperm penetration test. Preovulatory estradiol and LH peak decreased significantly compared to pre-implant insertion. Progesterone levels were within the normal limit. Cervical mucus and sperm penetration tests were not affected by Uniplant in the first 12 h. Twenty-four hours after Uniplant insertion, cervical mucus and sperm penetration tests were affected in 70.6% of the women. Forty-eight hours after implant insertion, the women were affected. Follicular rupture occurred in the majority of the women 48 h after implant insertion. Based on these results, it is possible to conclude that Uniplant can affect estradiol and LH preovulatory peaks and disrupt the process of cervical mucus production and sperm penetration, but it was unable to prevent ovulation when inserted in the preovulatory phase.