Early fragment removal on in vitro fertilization day 2 significantly improves the subsequent development and clinical outcomes of fragmented human embryos

Abstract

Objective: To determine whether fragment removal on in vitro fertilization (IVF) day 2 improved the subsequent development and pregnancy outcomes of fragmented embryos compared to similar-grade embryos without fragment removal.

Methods: This study was a retrospective analysis involving 191 IVF cycles in which all embryos had over 10% fragmentation (grade 3 or 4) on day 2 of the IVF-embryo transfer cycle from March 2015 to December 2017. IVF cycles were divided into the fragment removal group (n=87) and the no fragment removal group (n=104) as a control cohort. Before fragment removal, embryos with fragmentation on day 2 were incubated in Ca²⁺- and Mg²⁺-free biopsy medium under paraffin oil for 30 minutes. Microsurgical fragment removal was performed with later-assisted hatching and a handmade suction micropipette that had an outer diameter of 30 µm.

Results: There were no significant differences in the characteristics of the patients between the control and the fragment removal groups. After fragment removal and subsequent in vitro culture for 24 hours, the number of blastomeres (7.1±1.7 vs. 6.9±1.6) was comparable between the transferred embryos in the two groups, but the morphological grade of the embryos in the fragment removal group (1.9±0.7) was significantly higher than that of the control group (3.1±0.5, p<0.01). The clinical pregnancy (43.7%) and implantation rates (25.8%) in the fragment removal group were significantly higher than those in the control group (28.8% and 14.0%, respectively; p<0.05).

Conclusion: Early fragment removal on day 2 significantly improved the subsequent development and pregnancy outcomes of fragmented embryos.

Keywords: Day 2 embryos; Embryo fragmentation; Embryo grade; Fragment removal; Pregnancy outcome.

Figure 1. Improvements in the morphological grade and subsequent development of fragmented embryos after fragment removal. (A) Day 2 fragmented embryo (grade 3, GIII) before fragment removal, (B) day 2 embryo (grade 1, GI) after fragment removal, (C) day 3 embryo (GI) cultured for 24 hours after fragment removal. Magnification, ×250.