Outcomes of vitrified-warmed day-4 embryos after day-3 cleavage-stage biopsy

The objective of this study was to compare the post-warming survival rates of biopsied and non-biopsied day-3 embryos vitrified on day 4 and to evaluate the clinical outcomes of following transfers. This study included 18 preimplantation genetic diagnosis (PGD) patients and 18 non-PGD patients treated between January 2005 and January 2009 who had not achieved live births during their fresh embryo-transfer cycles and whose surplus embryos were cryopreserved on day 4. The embryo survival rate after warming in the PGD and non-PGD groups was similar (53/59, 89.8% versus 55/64, 85.9%, respectively; difference of 3.9% 95% CI -7.3 to 13.4). Vitrified embryo-transfer cycles yielded no significant differences between PGD and non-PGD groups in implantation rates (12/46, 26.1% versus 9/47, 19.1%, respectively; difference of 6.9%, 95% CI -9.7 to 22.2), clinical pregnancy rates (11/18, 61.1% versus 9/18, 50%, respectively; difference of 11.1%, 95% CI -20.6 to 40.6) and live birth rates (9/18, 50% versus 6/18, 33.3%, respectively; difference of 16.7%, 95% CI -15.1 to 44.8). These results showed that, in PGD cycles, embryos can be vitrified effectively on day 4 after biopsy on day 3. The objective of this study was to compare the post-warming survival rates of biopsied and non-biopsied day-3 embryos that vitrified on day 4 and to evaluate the clinical outcomes of following transfers. This retrospective study included 18 preimplantation genetic diagnosis (PGD) and 18 non-PGD patients treated between January 2005 and January 2009 who had not achieved live births during their fresh embryo transfer cycles and whose surplus were frozen on day 4. After warming in frozen embryo-transfer cycles, embryo survival with respect to embryo grades, implantation, clinical pregnancy and live birth rates were compared. The embryo survival rate after warming in the PGD group was similar to the survival rate in the non-PGD group (53/59, 89.8% versus 55/64, 85.9%, respectively; difference of 3.9%, 95% CI -7.3 to 13.4, P=0.701). Frozen embryo transfer yielded no significant differences between PGD and non-PGD groups in implantation rates (12/46, 26.1% versus 9/47, 19.1%, respectively; difference of 6.9%, 95% CI -9.7 to 22.2, P=0.581), clinical pregnancy rates (11/18, 61.1% versus 9/18, 50%, respectively; difference of 11.1%, 95% CI -20.6 to 40.6, P=0.737) or live birth rates (9/18, 50% versus 6/18, 33.3%, respectively; difference of 16.7%, 95% CI -15.1 to 44.8, P=0.499). These results showed that, in PGD cycles, embryos can be vitrified effectively on day 4 after biopsy on day 3.