ASSISTED REPRODUCTION TECHNOLOGIES Successful pregnancy following a novel endometrial preparation in a PCOS patient undergoing IVM: a case report

In-vitro fertilization (IVF) relies heavily on controlled ovarian stimulation to increase the number of available oocytes and embryos, and therefore the pregnancy rate. However, the side effects, such as nausea, mood swings, menopausal symptoms, ovarian hyperstimulation syndrome (OHSS), and potential cancer risk of ovarian stimulation may not be avoided. Therefore, the recovery of immature oocytes followed by in-vitro maturation (IVM) and fertilization is an attractive alternative to avoid the side effects of using gonadotrophin stimulation. In IVM, immature oocytes are retrieved from unstimulated or minimally stimulated cycles, then cultured using IVM culture media for maturation in vitro [1]. In comparison with conventional IVF, IVM technology is generally associated with the absence of OHSS, lower cost, and fewer complications. However, the efficiency of existing IVM technique is suboptimal because embryos generated from IVM exhibit frequent cleavage blocks and low implantation rate [2]. Women with polycystic ovarian syndrome (PCOS) are considered as the target population for this approach. This group of patients is extremely sensitive to ovarian stimulation and have a high potential for developing of OHSS [3]. In recent years, many improvements have been made in clinical and laboratory aspects of IVM treatment which have resulted in better pregnancy outcomes [4]. It was shown that pretreatment with FSH in the early days of folliculogenesis phase may increase the number of retrieved immature oocytes and/or maturation potential [5, 6]. In addition, hCG priming promotes some GV oocytes to reach the MI stage and increases the maturation rate of immature oocytes in vitro setting. Despite increased pregnancy rates following IVM in recent years, implantation rates are still lower than conventional IVF cycles. One possible explanation may be related to insufficient endometrial preparation during IVM cycles before ET [4, 7]. Here, we aim to report a novel endometrial preparation method in a PCOS case undergoing IVM.