Immunohistochemical staining of von Willebrand factor in endometrium of women during the first year of Norplant implants use

Effects of progestin-only contraceptives on the endometrium

INTRODUCTION

The contraceptive activity of synthetic progestins is mediated through three basic mechanisms: (a) An anti-gonadotrophic action leading to the inhibition of ovulation; (b) Changes in cervical mucus characteristics that inhibit sperm penetration and (c) desynchronization of the endometrial picture necessary for implantation.

AREAS COVERED

Mechanisms involved in the progestin-induced endometrium desynchronization are individually reviewed for each of the routes of administration and, whenever possible, by individual members of the various families of synthetic progestin derivatives.

EXPERT OPINION

For contraceptive purposes, progestins are today administered through several routes: orally, as injections, subdermally and via the vagina or the uterine cavity. Given this variety of modalities, their effects may differ, depending on the route of administration, concentration reached at the level of the endometrium and the duration of use. These are characterized by inactivation of the endometrium. Progestin-only contraception provides a safe and effective control of fertility regulation, although, they are associated with the problem of endometrial break through bleeding that may lead to discontinuation. Unfortunately, in spite of a major research effort over two decades, there is not, as yet, an established long-term intervention available to manage bleeding irregularities, making mandatory a deeper understanding of the mechanisms involved is required.

The effect of mefenamic acid on controlling irregular uterine bleeding secondary to Norplant use

The aim of this double-blind, placebo-controlled study was to evaluate the effect of mefenamic acid and placebo on controlling irregular uterine bleeding secondary to Norplant use. A total of 67 Norplant users attending the Family Planning Clinic of Chulalongkorn Hospital all had irregular bleeding. These women were randomly allocated into two groups. A total 34 users received mefenamic acid, 500 mg twice a day for 5 days, and placebos were given to the other 33 in the same manner. The total days of bleeding and spotting and the percentage of women in whom bleeding was stopped were analyzed in weeks 1 and 4. The percentage of subjects in whom bleeding was stopped during week 1 after initial treatment was significantly higher in the mefenamic acid group than the placebo group (76%, 27%; p < 0.001). In the follow-up period (4 weeks after initial treatment), a bleeding-free interval of > 20 days was found in 68% of the subjects treated with mefenamic acid and 33% treated with the placebo; the mean number of bleeding/spotting days was lower with mefenamic acid treatment (11.6 and 17.2 days; p < 0.05). The difference was statistically significant. It is concluded that mefenamic acid was more effective than placebo in short-term control of irregular bleeding and spotting associated with Norplant use.