Vitrification of human germinal vesicle oocytes; before or after in vitro maturation?

Background The utilization of immature oocytes derived from stimulated cycles could be of great importance, specially for urgent fertility preservation cases. The aim of the current study was to determine whether in-vitro maturation is more successful before or after the vitrification of these oocytes. MaterialsAndMethods The study was performed in a private IVF center. 318 germinal vesicle (GV) stage oocytes were collected from 104 stimulated oocyte donation cycles. Oocytes were divided into two groups according to whether vitrification was applied at the GV stage (group 1) or if they were in vitro matured to the MII stage and then vitrified (group 2). In a third, control group, oocytes were in vitro matured without being vitrified (group 3). In all three groups, survival rate after warming, maturation rate and MII-spindle/chromosome configurations were assessed. Chi-square test was used to compare rates between the three groups. Statistical significance was defined at P