Purpose: To assess the efficacy of a novel, defined vitrification procedure using recombinant human albumin (rHA) for cryopreservation of human blastocysts.
Design: Retrospective study.
Setting: Private IVF clinic.
Patients: 1,496 patients received vitrified/warmed embryo transfer (ET).
Methods: Surplus blastocysts, and blastocysts from patients undergoing elective embryo cryopreservation, were vitrified/warmed using Cryotop carriers in homemade solutions containing either human serum albumin (HSA) or rHA.
Main outcome measures: Clinical and neonatal outcomes regarding the vitrified/warmed ET procedures.
Results: The HSA and rHA groups had a total of 1,163 and 898 vitrified/warmed cycles, respectively. Embryo survival rates (98.7% vs. 98.9%, respectively) and the number of embryos transferred (1.08 ± 0.01 vs. 1.06 ± 0.01, respectively) were similar in the HSA and rHA groups. Clinical pregnancy rates/ET were higher (P < 0.05) in the rHA group (56.0%) than in the HSA group (51.5%). The HSA and rHA groups had similar live delivery rates/pregnancy (72.2% vs. 72.3%, respectively) and perinatal outcomes, including birth weight (2,988 ± 28 vs. 3,046 ± 26 g, respectively). Birth defects occurred in 0.9% and 1.6% of neonates in the HSA and rHA groups, respectively.
Conclusions: rHA effectively replaced HSA for human embryo vitrification procedures, and yielded high rates of pregnancy and live births after vitrified/warmed ET. This new approach will support the development of defined ART systems, which will eliminate the variation and risks associated with the use of blood-derived products.