Open versus closed oocyte vitrification in an oocyte donation programme: a prospective randomized sibling oocyte...

Area of Science:

• Reproductive medicine
• Embryology
• Cryobiology

Background:

• Health authorities express caution regarding potential cross-contamination with open vitrification devices.
• Limited data exists on the efficiency of closed vitrification devices, leading to their continued use.

Purpose of the Study:

• To compare the donor oocyte survival rates between the CryotopSC (open vitrification) and CBSvit (closed vitrification) devices.
• To evaluate embryological outcomes, including survival, fertilization, and embryo development, following vitrification with both devices.

Main Methods:

• A prospective randomized sibling oocyte study involving 48 donors and comparing 253 oocytes vitrified with CBSvit and 257 with CryotopSC.
• Oocytes were vitrified using either the CBSvit (closed) or CryotopSC (open) device and warmed for subsequent assessment of survival and embryological development.
• Statistical analysis was performed to compare outcomes between the two devices, with a 10% difference defined as proof of CryotopSC superiority.

Main Results:

• No significant difference in oocyte survival rates after warming (93.7% for CBSvit vs. 89.9% for CryotopSC).
• CryotopSC showed a significantly lower degeneration rate after ICSI (6.1% vs. 11.4%) and a higher rate of first mitosis completion (52.1% vs. 34.1%).
• Embryos in the CryotopSC group had a significantly higher cell number on Day 3 (7.6 ± 2.8 vs. 6.8 ± 2.8), with similar overall embryo quality distribution.

Conclusions:

• Both CryotopSC and CBSvit devices exhibit comparable oocyte survival rates.
• The CryotopSC device demonstrates superior performance in terms of reduced degeneration and enhanced embryo development.
• The study highlights the efficiency of a closed vitrification device (CBSvit), potentially alleviating concerns about cross-contamination during handling and storage.