Comparison between headfirst and tail-first direction of sperm for intracytoplasmic sperm injection

Background: Intracytoplasmic sperm injection (ICSI) is used for assisted fertilization. Sperm can be injected headfirst and tail-first. This study aimed to investigate the effect of the headfirst or tail-first injection of sperm into the cytoplasm during ICSI on oocyte survival, fertilization, blastocyst development, implantation, and clinical pregnancy.Methods: A prospective study was carried out by enrolling 79 women who had undergone IVF with male factor infertility between September 2016 and June 2019. The sibling oocytes were randomly inseminated by headfirst ICSI (405 oocytes) and tail-first ICSI (393 oocytes). After fertilization, the embryos were cultured until blastocyst and single embryos were transferred under ultrasound guidance.Results: There was no difference in survival rates (98.8% versus 98.9%; p=0.551), fertilization rate (71.5% versus 74.8%; p=0.333), and formation of blastocysts (50.7% versus 51.2%; p=0.970) between headfirst and tail-first direction of sperm during ICSI. Implantation and clinical pregnancy were also not significantly different.Conclusions: The outcomes showed that the direction of sperm injection (headfirst and tail-first) had no significant effect on oocyte survival, fertilization, blastocyst development, implantation, and clinical pregnancy.

Comparison of short and long co-incubation time of gametes for in vitro fertilization

Background: The short and long co-incubation time of gametes for in vitro fertilization are still debatable issues. This study aims to investigate the effects of short and long co-incubation time of gametes on fertilization, polyspermy, embryonic developmental potential, and clinical outcomes.Methods: Sixty-five patients undergoing IVF treatment were invited to participate in the study between May 2017 and March 2019. Ovarian hyperstimulation was prescribed and oocytes were obtained by trans-vaginal aspiration under ultrasound guidance. Sibling oocytes were randomly allocated to short co-incubation for 4 hours (Group I) in 352 oocytes and long co-incubation for 16-18 hours in 363 oocytes (Group II). Rescue ICSI was carried out if total fertilization failure was documented. Fertilization, embryonic development, and pregnancy outcomes were determined.Results: No significant differences between short and long co-incubation were found in fertilization, polyspermy, cleavage, blastocyst, implantation, clinical pregnancy, and live birth rates.Conclusions: The present study showed that short co-incubation of gametes had no significant difference in fertilization, polyspermy, embryo development, and pregnancy outcomes when compared to long co-incubation. The short co-incubation with early cumulus cell removal and rescue ICSI may have the potential to help a couple who had total fertilization failure.