Comparison of ovarian follicular activity during treatment with a monthly injectable contraceptive and a low-dose oral contraceptive.

Ovarian follicular development occurs during treatment with combined and progestin-only oral contraceptive (OC) pills and progestin-containing subdermal implants, and can be associated with the development of persistent functional cysts that may require surgical removal. Lunelle is a once-a-month injectable contraceptive containing estradiol cypionate 5 mg and medroxyprogesterone acetate 25 mg. A randomized, comparative study was undertaken to compare the effect on ovarian follicular activity associated with use of Lunelle and a low-dose OC. A total of 30 ovulatory subjects were randomly assigned to receive two cycles of treatment with either an OC containing ethinyl estradiol 20 microg and 0.1 mg levonorgestrel or Lunelle. During the second cycle of treatment, pelvic sonography was performed every 4 days, at which time the maximum follicle diameter was measured. Study end points were the presence of follicles >/=10, 20, and 30 mm. In all, 13 of 15 subjects in the OC group and 14 of 15 in the Lunelle group completed the study. Follicles measuring >/=10 mm were present in 11 of 13 (84.6%) in the OC users and in four of 14 (28.6%) in the Lunelle users (p <0.05). In the OC group, six of 13 subjects (46.1%) developed follicles >/=20 mm, and one of 13 (7.7%) developed follicles >/=30 mm. No subjects in the Lunelle group developed a follicle >/=20 mm in diameter. This study indicates that Lunelle is associated with a significantly lower incidence of ovarian follicular development compared to that of an OC containing 20 microg ethinyl estradiol and 0.1 mg levonorgestrel.