Outcomes of intracytoplasmic sperm injection using the zona pellucida-bound sperm or manually selected sperm

Zona pellucida (ZP)-bound sperm used for intracytoplasmic sperm injection (ICSI) enhances embryo quality, implantation, and clinical pregnancy rates. This study aimed to assess the pregnancy outcomes and clinical significance of ICSI with ZP-bound sperm.

A total of 84 infertile couples who underwent cycles of ICSI following failed in vitro fertilization between June 2012 and February 2014 were enrolled and randomized (1:1): in the treatment group, ICSI was performed using ZP-bound sperm; in the control group, ICSI was performed in a standard manner. Rates of fertilization, cleavage, high-quality embryos, and clinical pregnancy were compared between the two groups.

There were no significant differences in age, infertile period, gonadotrophin dose, number of metaphase II oocytes, and number of embryo transfers between the two groups (P > 0.05). The clinical pregnancy rate was higher in the treatment group than in the control group, but without statistical significance (60.5 vs. 47.6 %, P > 0.05). No significant differences in the rates of fertilization and cleavage were observed (83.0 vs. 81.6 %, and 96.3 vs. 96.5 %, both P > 0.05), but higher rates of high-quality embryos and useable embryos were observed with ZP-bound sperm compared with controls (66.1 vs. 50.8 % and 76.0 vs. 66.3 %, both P < 0.05).

ICSI using ZP-bound sperm might increase the embryo quality and number of useable embryos, possibly improving the clinical pregnancy outcome of ICSI.