Artificial oocyte activation after intracytoplasmic morphologically selected sperm injection: A prospective randomized sibling oocyte study

This study aimed to evaluate the effect of artificial oocyte activation (AOA) by calcium ionophore after intracytoplasmic morphologically selected sperm injection (IMSI) on fertilization, cleavage rate and embryo quality. A total of 194 oocytes from 21 cycles from women with a history of low fertilization rate accompanying teratozoospermia were enrolled over a 3-month period. Mature oocytes from each patient were randomly allocated into two groups after IMSI. In the study group, half of the patients' oocytes (n = 97) were exposed to AOA, and in the control group (n = 97), AOA was not applied. The mean number of mature oocytes, fertilization and cleavage rates were similar between the study and control groups (p > 0.05 for each). However, fertilized oocytes of the AOA group were less likely to produce top quality embryos when calculated per fertilized oocyte (28/80; 35.0% versus 38/71; 53.5%, respectively; p = 0.024) and also per cycle (13/21; 61.9% versus 20/21; 95.24%, respectively; p = 0.006). Our study indicates that AOA may not improve fertilization rates after IMSI and may even reduce the ability of a successfully fertilized oocyte to develop into a top quality embryo. AOA should, therefore, be applied to cases with a defined oocyte activating deficiency.