Scanning electron microscopic (SEM) changes of the endometrium in women taking high doses of levonorgestrel as emergency postcoital contraception.
Endometrial surface changes by scanning electron microscope were studied in three women who intentionally took high doses of levonorgestrel as an emergency postcoital contraceptive. Based upon findings of a close link between endometrial receptivity and surface integrity, significant alterations of the uterine lining structure may represent a drug effect accomplishing endometrial contraception. High doses of levonorgestrel (4-6 times more than recommended) caused detectable changes on the surface regardless of the menstrual cycle phase when the medication was taken. Cycle classification was based on estradiol and progesterone hormone levels, which corresponded to the menstrual diary. Comparison to control specimens displayed marked restructuralization of the endometrium. As a main feature, the number of ciliated cells were reduced, and cilia disappeared in the proliferative and periovulatory phase. In the secretory phase, pinopodia disappeared and the endometrial integrity broke down. The contraceptive effect of levonorgestrel seems to be accomplished by alteration of the endometrial surface and, therefore, receptivity.