The clinical outcomes of vitrified blastocysts on in vitro maturation cycles

Abstract

OBJECTIVE: Even if cryopreservation is now a routine procedure in human IVF, there are a few reports that blastocysts generated from in vitro maturation (IVM) were frozen using vilification. The purpose of this study is to report production and cryopreservation of blastocysts from IVM. DESIGN: A retrospective study. MATERIALS AND METHODS: The blastocysts produced from IVM cycles were frozen. The embryos were vitrified using an EM grid following artificial shrinkage. The vitrification solution was composed of DPBS containing 20% (v/v) SSS, 40% (v/v) ethylene glycol, 18% (w/v) Ficoll, and 0.3 M sucrose and vitrification was prepared according to the previously described method (Son et al., 2003). Thawing of the vitrified embryos was carried out using a two-step cryoprotectant dilution method (Lee et al., 2006). Thawed blastocysts were cultured for overnight, and then these were observed and transferred. RESULTS: Total 874 blastocysts (240 cycles, 231 patients) were cryopreserved on IVM cycles from 2004 to 2009. Among these, 274 blastocysts (104 cycles, 94 patients) were thawed and transferred. It showed a high rate of post-thawing survival (94%, 259/274). After the transfer of 254 embryos (2 ± 0.82), 44 women (43%) became clinically pregnant and 55 embryos (22%) implanted. Among these women, 21 pregnancies ended in miscarriage, 18 healthy babies were born in 16 deliveries, and 8 patients' pregnancies are currently ongoing. CONCLUSION: The blastocysts produced from IVM could be safely cryopreserved by vitrification using an EM grid. Thus, vitrification is an effective and practical method for cryopreservation in IVM.