BACKGROUND: Focus on the hatching process has so far been in the field of fresh embryos. Cryopreserved-thawed embryos have a lower rate of pregnancy than fresh embryos, which might be due to hardening of the zona pellucida. METHODS: During a 2 year period, a prospective randomized study enrolling 253 cryopreserved-thawed cycles was performed on day 2 embryos. Pseudorandomization to assisted hatching or a control group was done on the basis of even and odd dates for thawing. One hour before embryo transfer, hatching was carried out using acidic Tyrode's solution. RESULTS: Among 136 embryos exposed to assisted hatching, 11.4% (30) were implanted compared with only 5.8% (13) of 117 embryos not exposed to assisted hatching (P<0.05, chi(2) test). No difference in the rate of clinical pregnancy and positive serum HCG was observed between the two groups. Very few women >38 years old were included in the study, and no significant difference according to age could be found between the groups. CONCLUSIONS: These results show that assisted hatching using acidic Tyrode's solution increases the implantation rate of cryopreserved-thawed embryos (P<0.05).
RCT Entities:
BACKGROUND: Focus on the hatching process has so far been in the field of fresh embryos. Cryopreserved-thawed embryos have a lower rate of pregnancy than fresh embryos, which might be due to hardening of the zona pellucida. METHODS: During a 2 year period, a prospective randomized study enrolling 253 cryopreserved-thawed cycles was performed on day 2 embryos. Pseudorandomization to assisted hatching or a control group was done on the basis of even and odd dates for thawing. One hour before embryo transfer, hatching was carried out using acidic Tyrode's solution. RESULTS: Among 136 embryos exposed to assisted hatching, 11.4% (30) were implanted compared with only 5.8% (13) of 117 embryos not exposed to assisted hatching (P<0.05, chi(2) test). No difference in the rate of clinical pregnancy and positive serum HCG was observed between the two groups. Very few women >38 years old were included in the study, and no significant difference according to age could be found between the groups. CONCLUSIONS: These results show that assisted hatching using acidic Tyrode's solution increases the implantation rate of cryopreserved-thawed embryos (P<0.05).
Authors: Alex J Polotsky; Jennifer L Daif; Sangita Jindal; Harry J Lieman; Nanette Santoro; Lubna Pal Journal: Fertil Steril Date: 2008-10-11 Impact factor: 7.329