Time-lapse monitoring of zona pellucida-free embryos obtained through in vitro fertilization: a retrospective case series

Objective To report time-lapse monitoring of human oocytes in which the damaged zona pellucida was removed, producing zona-free (ZF) oocytes that were cultured until the blastocyst stage in time-lapse incubators. Design Retrospective case series. Setting Private infertility clinic. Patient(s) Infertile patients (n = 32) undergoing minimal ovarian stimulation or natural cycle IVF treatment between October 2012 and June 2014. Intervention(s) Intracytoplasmic sperm injection (ICSI) fertilization of ZF oocytes, prolonged embryo culture in time-lapse incubators, elective vitrification, and subsequent single vitrified-thawed blastocyst transfer (SVBT). Main Outcome Measure(s) Rate of fertilization, cleavage and blastocyst development, live-birth rate per SVBT cycle. Result(s) In spite of advanced maternal age (39 ± 4.2; range, 30–46 years), good fertilization (94%), cleavage (94%), and blastocyst development rates (38%) were reached after fertilization and culturing of ZF oocytes/embryos. All thawed ZF blastocysts survived, and up to this date seven SVBT transfers were performed, yielding three (43%) term live births with healthy newborns. Conclusion(s) Time-lapse imagery gives a unique insight into the dynamics of embryo development in ZF embryos. Moreover, our case series demonstrate that an oocyte with a damaged zona pellucida that has been removed could be successfully fertilized with ICSI, cultured until blastocyst stage in a time-lapse incubator and vitrified electively for subsequent use.