The effect of pipette- and laser-induced blastocyst collapse before vitrification on their re-expansion and clinical outcome after warming

Research question: What are the effects of pipette- versus laser-assisted artificial blastocyst collapse (ABC) on the morphokinetics of warmed blastocyst re-expansion, and what is the potential effect on treatment outcomes?

Design: Surplus blastocysts were extracted from 203 patients. These were divided into three groups: study group A, artificial collapsed by the aspiration of blastocoel fluid with a pipette; study group B, trophectoderm opened with a laser pulse; control group, no manipulation before vitrification was performed. During the 5-year study period, 257 associated single-warm blastocyst transfers were scheduled. The start and duration of the re-expansion process before transfer were annotated. Pregnancy and live birth data were also collected for the transfers.

Results: The overall blastocyst survival rate was 96.9%, with no effect observed as a result of the two ABC methods. The re-expansion of blastocysts in study group B was initiated significantly sooner after warming (0.50 ± 0.37 h) than in group A (0.79 ± 0.56 h) or the control group (1.22 ± 1.00 h). The duration of the re-expansion process was significantly reduced in study groups A (P = 0.021) and B (P = 0.004) compared with the control group. The embryos of participants who achieved a live birth had a significantly (P < 0.001) faster start of re-expansion (0.60 ± 0.42 h) than the embryos in those who did not produce an ongoing pregnancy (1.05 ± 0.92 h).

Conclusions: Laser-treated blastocysts exhibited substantially shorter re-expansion times. Because faster re-expansion of the blastocyst is associated with positive treatment outcomes, the laser technique should be prioritized over the pipetting technique if ABC is considered.