How does closed system vitrification of human oocytes affect the clinical outcome? A prospective, observational, cohort, noninferiority trial in an oocyte donation program

In a trial to evaluate the clinical outcome of donated oocytes vitrified in a closed system compared with fresh siblings, the two groups had similar results.

Volume 106, Issue 6, Pages 1348-1355


Achilleas Papatheodorou, Ph.D., Pierre Vanderzwalmen, Ph.D., Yannis Panagiotidis, Ph.D., Stamatis Petousis, M.D., Ph.D., Giuseppe Gullo, M.D., Evangelia Kasapi, Maria Goudakou, Ph.D., Nikos Prapas, M.D., Ph.D., Kostas Zikopoulos, M.D., Ph.D., Ioannis Georgiou, Ph.D., Yannis Prapas, M.D., Ph.D.



To evaluate whether is possible to vitrify oocytes in an aseptic (hermetically closed) fashion and maintain clinical results comparable with those of fresh oocytes.


Prospective, observational, cohort, noninferiority trial.


Private in vitro fertilization center.


One hundred eighty-four recipients of donated vitrified oocytes.


Closed system vitrification.

Main Outcome Measure(s)

Pregnancy rate per cycle and clinical pregnancy rate per cycle.


No statistically significant differences were observed between two groups regarding the pregnancy rate per cycle (63.1% vs. 60.9%) or the clinical pregnancy rate per cycle (55.4% vs. 58.7%). Biochemical pregnancy rate was statistically significantly higher in the fresh group (7.6% vs. 2.2%). The mean number of embryos transferred was similar (2.0 ┬▒ 0.0 vs. 1.97 ┬▒ 0.3). Concerning embryologic data, there were no statistically significant differences regarding the fertilization, cleavage, top quality day-3 embryo, or blastocyst rates, whereas the top quality blastocyst rate on day 5 was statistically significantly higher in the fresh oocyte group (31.7% vs. 26.1%).


Aseptically (in a closed system) vitrified oocytes show similar clinical efficiency compared with their sibling fresh oocytes.

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