Human embryo fragmentation in vitro and its implications for pregnancy and implantation

Abstract

Objective: To evaluate the effects of fragmentation and fragment removal in day 3 human embryos on implantation and pregnancy.

Design: Retrospective analysis of ETs homogeneous with respect to embryo fragmentation.

Setting: A program of IVF-ET.

Patient(s): The study population consisted of 2,410 patients.

Intervention(s): The degree and pattern of fragmentation were evaluated on days 2 and 3; microsurgical fragment removal was performed after assisted hatching on day 3.

Main outcome measure(s): Clinical pregnancy and implantation rates.

Result(s): The degree and pattern of fragmentation significantly impact pregnancy and implantation. With the application of microsurgical fragment removal before ET, embryos with 6%-35% fragmentation implant with similar frequency. The presence of large fragments (type IV) is detrimental to the developing embryo, whereas localized or small and scattered fragments do not significantly affect implantation.

Conclusion(s): The potential of fragmented embryos for implantation is determined partly by the distribution of fragments. Adoption of an embryo classification system reflecting types of fragmentation is advisable. The use of microsurgical fragment removal significantly alters the course of development for some embryos and improves their implanting potential.