Chapter 7 - Embryo Assisted Hatching for IVF

Summary

The zona pellucida surrounding human embryos may be breached to facilitate the process of hatching following in vitro culture, either to promote implantation or in preparation for removal of cells for pre-implantation genetic testing (PGT). This technique is referred to as ‘assisted hatching’ (AH). Since publication of the first studies on AH in the 1990s aimed at improving implantation and pregnancy rates, in which a chemical method was used to breach the zona, multiple variations of the technique have been attempted by practitioners. Application of AH prior to fresh embryo transfer in young, good-prognosis patients has been repeatedly shown to be ineffective. The method continues to be successfully applied to fresh embryos for embryo biopsy and outcome data support application in frozen–thawed (vitrified–warmed) embryos and oocytes prior to transfer. Proper training, patient selection and methodology are important to the clinical success of AH as any other micromanipulation technique. Complete removal of the zona pellucida to avoid trapping has been proposed as an alternative to partial breach but studies are scarce.