Objective: To determine whether subdermal levonorgestrel implants induce endometrial expression of glycodelin.
Design: Cross-sectional, blinded study.
Setting: University clinic.
Patient(s): One hundred and eight women with subdermal implants and 19 postmenopausal women.
Intervention(s): Endometrial biopsies, curettages, and hysterectomies.
Main outcome measure(s): Endometrial glycodelin expression was examined through immunohistochemistry, in situ hybridization, and morphologic endometrial dating.
Result(s): Overall, 80% of the endometrial specimens obtained from women with subdermal levonorgestrel implants stained positive for glycodelin. Endometrial morphology of these women showed proliferative (71%), inactive/weakly proliferative (19%), menstrual or regenerating (6.5%), and other patterns (2.8%). Of these, 79%, 71%, 100%, and 100% were glycodelin positive, respectively. Nineteen specimens were obtained during the midcycle when glycodelin is not normally expressed: of these, 89% stained positive for glycodelin. Implant-related amenorrhea was associated with endometrial glycodelin expression in 58% of the women, whereas the endometrium specimens obtained from women with postmenopausal hypoestrogenic amenorrhea contained no detectable glycodelin.
Conclusion(s): Subdermal levonorgestrel implant use is often associated with endometrial expression of glycodelin. Because glycodelin has been shown to inhibit sperm-egg binding, the induction of glycodelin may contribute to the contraceptive activity of the implant.