Outcome of cryotransfer of embryos developed from vitrified oocytes double vitrification has no impact on delivery rates

Capsule:
The delivery rate after vitrification of embryos derived from vitrified oocytes is not impaired by double vitrification.

Authors:
Ana Cobo, Ph.D., Damià Castellò, Ph.D., Begoña Vallejo, M.L.T., Carmela Albert, Ph.D., José María de los Santos, Ph.D., José Remohí, M.D.

Volume 99, Issue 6, Pages 1623-1630.e7, May 2013

Abstract:

Objective:
Evaluate the outcome of cryotransfer of embryos developed from vitrified oocytes.

Design:
Retrospective cohort study.

Setting:
Private university-affiliated IVF center.

Patient(s):
Women undergoing warming cycles in which vitrified embryos were developed from vitrified or fresh oocytes.

Intervention(s):
Vitrification by the Cryotop open device.

Main Outcome Measure(s):
Delivery rate (DR) per warming cycle.

Results:
A total of 471 warming cycles of 796 vitrified embryos developed from vitrified oocytes (group 1) and 2629 warming cycles of 4394 vitrified embryos derived from fresh oocytes (group 2) were evaluated. Overall survival rates were (97.2% (CI95%95.9-98.6) vs. 95.7% (CI95%94.9-96.4) respectively (NS). The delivery rate (DR) per warming cycle was 33.8% (group 1) and 30.6% (group 2). Double vitrification had no effect on DR (OR=0.867; CI95% 0.657-1.203) (NS). Confounding factors (ovum donation or autologous cycles; day-3 or blastocysts embryo transfer ET); natural or hormonal replacement therapy for ET; single or double ET; previous cycles, number of oocytes, doses of gonadotrophines and E2 levels the day of hCG) are not conditioning the effect of double vitrification on the delivery rate (OR=0.872; CI95% 0.702-1.084).

Conclusions:
Vitrification at early cleavage or blastocyst stage of embryos obtained from previously vitrified oocytes has no effect on the DR/ warming cycle.

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