Capodanno F, Daolio J, De Feo G, Falbo A, Morini D, Nicoli A, Braglia L, Villani M, La Sala GB, Parmegiani L, Aguzzoli L. A monocentric analysis of the efficacy of extracellular cryoprotectants in unfrozen solutions for cleavage stage embryos.
Reprod Biol Endocrinol 2019;
17:84. [PMID:
31656205 PMCID:
PMC6815413 DOI:
10.1186/s12958-019-0519-2]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 08/29/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND
In the absence of international guidelines indicating the usage of vitrification rather than slow-freezing, the study aim was to analyze a large cohort of slow-frozen/thawed embryos to produce a rationale supporting the standardization of IVF cryopreservation policy.
METHODS
This retrospective analysis included 4779 cleavage stage embryos cryopreserved by slow-freezing/thawing from September 2009 to April 2017 at a single Center. Biological and clinical outcomes of three different commercial kits adopted sequentially, i.e. Vitrolife Cleave Kit® from Vitrolife (kit 1) vs. K-SICS-5000 Kit® and K-SITS-5000 Kit® from Cook Medical (kit 2) and Freeze/Thaw 1™ Kit® from Vitrolife (kit 3) were collected and compared in the light of cryoprotectants composition.
RESULTS
Kit 3 compared to kit 1 and kit 2 showed significantly (P < 0.001) higher embryo survival (79.9% vs. 75.6 and 68.1%, respectively) and frozen embryo replacement (91.5% vs. 86.5 and 83.3%, respectively) rates, and significantly (P < 0.001) lower blastomere degeneration rate (41.5% vs. 43.6 and 52.4%, respectively). No significant difference for clinical outcomes was observed among kits. Only a slight positive trend was observed for kit 3 vs. kit 1 and kit 2 on delivery rate per thawing cycle (7.12% vs. 4.19 and 4.51%, respectively; P < 0.058) and live birth rate (3.07% vs. 2.59 and 1.93%, respectively, P < 0.069). Thawing solutions of kit 3 were similar to those of any warming protocol.
CONCLUSIONS
A defined concentration of extracellular cryoprotectants in thawing/warming solutions had a beneficial effect on the embryo cryosurvival rate. Results could provide the rationale for the adoption of a single standardized warming protocol.
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