Estudio clínico comparativo. Resultado de la vitrificación y desvitrificación de embriones humanos con dos tipos de sistemas abiertos: Cryotop vs Cryolock

Background: Through the past years embryo vitrification has become a daily basis therapeutical assisted reproductive technique in many countries worldwide. We have worked with Cryotop open system device for several years, yielding survival rates above 90% and pregnancy rates of 60%. Now we introduced to our clinic the Cryolock open system device for embryo vitrification on day 3 or 5 of development. Objectives: To compare the effectiveness of the new open system Cryolock with Cryotop, and to assess the survival and pregnancy rates after devitrification and transfer. Material and method: A retrospective analysis of the procedures of defrosting and transferring (done in our clinic during 2009) was performed. Results: We found that there is no significant difference between them, and furthermore, Cryolock device yields as well optimum survival and pregnancy rates: 90% and 60%, respectively. Thus, we recommended Cryolock device for embryo vitrification. Conclusions: Although Cryotop presents a thinner filament compared to Cryolock, such a difference does not significantly affect survival and pregnancy rates when they are devitrified and transferred to patients. The use of Cryolock is recommended to embryo vitrification.