Influence of embryo transfer on blastocyst viability

Objective To investigate the impact of injection speeds of the transferred load on embryo viability. Design Laboratory model for in vitro simulation of embryo transfer (ET). Setting Academic research institutes of reproduction biotechnology and private centers of reproductive medicine. Animal(s) Mouse hybrid F1 females, C57bl/10J × CBA-H (N = 15), aged 2 to 3 months. Intervention(s) In vitro exposure of mouse blastocysts to either fast ET with an ejection speed of the transferred load of >1 m/s or slow ET with an ejection speed of Main Outcome Measure(s) Morphologic changes and apoptotic index of blastocysts. Result(s) Morphologic changes in response to ET were most prevalent in blastocysts exposed to fast ET. The mean apoptotic index was 52% in the group exposed to fast ET, 25% in the group exposed to slow ET, and 12.8% in control group. Conclusion(s) Fast ejection of the transferred load can trigger both morphologic changes and apoptosis in mouse blastocysts. A reduction of the ejection speed of the transferred load minimizes injury to the embryos. Therefore, embryos should be transferred at the lowest possible speed.