Potential enhancement of endometrial receptivity in cycles using controlled ovarian hyperstimulation with antiprogestins: A hypothesis

Objective: To manipulate the luteal endometrial progression by the use of antiprogestins. Design: Prospective controlled clinical trial. Setting: The IVF program of the University of Southern California School of Medicine, Los Angeles, California. Patient(s): Thirteen oocyte donors and 20 oocyte recipients. Intervention(s): Controlled ovarian hyperstimulation of oocyte donors, administration of two doses of 2.5 mg of RU486 to the study group, and endometrial biopsies. Main Outcome Measure(s): Serum E(2) and P levels, histologic dating of the endometrium, endometrial ultrastructure by scanning electron microscopy. Result(s): No difference in serum E(2) or P levels was noted after RU486 administration. The histologic dating was advanced in oocyte donors as compared with recipients undergoing artificial cycles but returned to normal (in phase) after RU486. Pinopods were noted in all recipient biopsies and in donors treated with RU486 but in only one of four biopsies in donor controls. Conclusion(s): Cycles with controlled ovarian hyperstimulation are associated with high early luteal P levels and advanced endometrial histology. Low doses of RU486 may correct the precocious luteinization and restore endometrial receptivity.