In Vitro Maturation and Time-Lapse Imaging of Immature Human Oocytes: A Direction Toward Clinical Applications

Recently, multiple teams reported the successful utilization of denuded oocytes matured in vitro after controlled ovarian stimulation, as well as their small but significant contribution to cumulative live-birth rates after intracytoplasmic sperm injection (ICSI). Published data are in favor of rescue ICSI when mature oocytes are obtained one day after oocyte pickup, the clinical contribution being higher for patient with advanced maternal age, low ovarian response to COS, low maturation rate, or low fertilization rate. From a strictly resource-oriented perspective, rescue ICSI of immature oocytes may not be cost-effective as it would require additional expenses related to consumables, media, and embryologist time and as the developmental potential of such oocytes is consistently decreased across reported studies compared to their sibling mature oocytes. Being able to select the right clinical context as well as the right oocytes to fertilize to optimize outcome and resources spent is thus of significant clinical value. In that regard, even if more costly than conventional culture, time-lapse imaging may play an important role as morphokinetic markers of oocyte maturation and oocyte developmental potential have been described. However, the limited number of reported cases warrants for the restricted use of rescue ICSI only in registered clinical trials with long-term follow-up of children obtained from this still experimental procedure.