RESUMO
Cryopreservation of human embryos has become an essential part of assisted reproduction. It limits the number of embryo transferred while supernumerary embryos can be transferred in subsequent cycles, however, it is associated with zonal hardening, which lowers the success rate in the majority of (ICSI) centres, associated with decreased implantation rate and clinical pregnancy rates. Assisted hatching has been used to induce microdissection of the zona pellucida. Many techniques have been used, such as mechanical, chemical, piezo and laser techniques. AIM: To compare the efficacy of laser assisted hatching of vitrified embryos and fresh embryos with regards to implantation rate and clinical pregnancy rate. STUDY DESIGN: Prospective randomised study. PATIENTS AND METHODS: One hundred twenty women with fresh embryos scheduled for (ICSI) were randomised in two groups; laser assisted hatching (LAH) group (test group), containing 60 women and the other is (non LAH) (control group). Second group with 120 women with frozen embryos were randomised in (LAH group) and (non LAH group). On the day of embryo transfer, 1.48 µm Infrared Diode laser, class 1 M, was used in test group to induce zonal microdissection, the quality and safety of embryos is assessed morphologically after hatching. On the other hand, the zona of the control group were left intact. Both clinical pregnancy and implantation rates were estimated. RESULTS: Laser assisted hatching group had clinical pregnancy and implantation rates of 38% and 50%, respectively. Non laser assisted hatching group had lower clinical pregnancy and implantation rates; 30% (p = .442) and 33% (p = .095), respectively, with no statistically significant difference p < .05. CONCLUSION: LAH does not improve statistically both pregnancy rate and implantation rate in fresh embryos. However, there is improvement in both implantation and pregnancy rate in Vitrified group.