Chemical activation of oocytes in different types of sperm abnormalities in cases of low or failed fertilization after ICSI: a prospective pilot study

This study evaluated the influence of chemical activation of oocytes in cases with abnormal sperm morphology and previous low intracytoplasmic sperm injection (ICSI) fertilization rate. Fertilization, early cleavage and embryo quality were assessed according to individual abnormal sperm morphology with or without chemical activation of oocytes after ICSI in 56 consecutive cycles with different types of abnormal sperm morphology (A = amorphous head, B = tapered head, C = bent neck) having a history of previous failed or low fertilization rate. Chemical activation significantly increased fertilization rate in subgroup A (82.7 versus 36.7%, P = 0.0008) and subgroup B (81.7 versus 39.3%, P = 0.005), but not in subgroup C (48.2 versus 49.4%). There was no effect on early cleavage (25 h after injection) or on the number of good embryos on day 2 (48 h after injection) in the different subgroups. Chemical activation of oocytes after ICSI in selected cases with previous history of failed or low fertilization rate and 100% sperm abnormality may increase fertilization rate in some sperm morphological abnormalities (amorphous head and tapered head) but not in others (bent neck). However, there was no significant effect on early cleavage or number of good embryos in all subgroups.