N De Munck1, S Santos-Ribeiro2, D Stoop3, H Van de Velde4, G Verheyen3. 1. Centre for Reproductive Medicine, UZ Brussel, Laarbeeklaan 101, Brussels, Belgium Reproduction and Genetics, Vrije Universiteit Brussel (VUB), Laarbeeklaan 101, Brussels, Belgium neelke.demunck@uzbrussel.be. 2. Centre for Reproductive Medicine, UZ Brussel, Laarbeeklaan 101, Brussels, Belgium Department of Obstetrics, Gynaecology and Reproductive Medicine, Hospital Universitário de Santa Maria, Avenida Professor Egas Moniz, Lisbon 1649-035, Portugal. 3. Centre for Reproductive Medicine, UZ Brussel, Laarbeeklaan 101, Brussels, Belgium. 4. Centre for Reproductive Medicine, UZ Brussel, Laarbeeklaan 101, Brussels, Belgium Reproduction and Genetics, Vrije Universiteit Brussel (VUB), Laarbeeklaan 101, Brussels, Belgium.
Abstract
STUDY QUESTION: Is the survival of donor oocytes with the CryotopSC device superior to the survival with the closed CBSvit device? SUMMARY ANSWER: The CryotopSC device and the CBSvit device showed similar survival rates. WHAT IS KNOWN ALREADY: Health authorities are cautious about possible cross contamination during liquid nitrogen storage or handling when working with open vitrification devices. At present, the use of open devices is still allowed since little information is available on the efficiency of closed devices. STUDY DESIGN, SIZE, DURATION: A prospective randomized sibling oocyte study was performed in the Centre for Reproductive Medicine (UZBrussel) between January 2014 and July 2015. The survival after warming and the embryological outcome of donor oocytes vitrified using two devices was compared: the CBSvit device (closed vitrification and closed storage) and the CryotopSC device (open vitrification and closed storage). A difference of 10% was defined to prove the superiority of the CryotopSC device. In total, 250 warmed oocytes were needed in each arm. PARTICIPANTS/MATERIALS, SETTING, METHODS: Oocytes from 48 donors were included in the study: 253 vitrified with the CBSvit device and 257 with the CryotopSC device. Equal numbers of oocytes from both devices and originated from the same donor cycle were allocated to each of 78 recipients, in order to exclude donor and recipient (male factor) effects. MAIN RESULTS AND THE ROLE OF CHANCE: There were no differences found between the CBSvit and the CryotopSC in terms of survival after warming (93.7 versus 89.9%) or fertilization per injected oocyte (74.3 versus 81.4%). The degeneration rate after ICSI was significantly higher for the CBSvit device: 11.4 versus 6.1% (P = 0.041). A significantly higher number of zygotes in the CryotopSC group finished their first mitosis 25-27 h post-injection (34.1 versus 52.1%, P = 0.001). On Day 3, the overall embryo quality distribution did not vary between groups, but a significantly higher cell number was obtained in the CryotopSC device: 6.8 ± 2.8 versus 7.6 ± 2.8 (P = 0.01). The utilization rate per mature oocyte, per surviving oocyte or per fertilized oocyte did not differ. The embryos with the highest quality were selected for transfer on Day 3. The clinical pregnancy rate per transfer cycle was 36.5%. LIMITATIONS, REASONS FOR CAUTION: The results of this study should not be extrapolated to other female groups, since oocytes from young fertile donors were used in this study. WIDER IMPLICATIONS OF THE FINDINGS: In many countries, the use of open devices is still allowed due to the limited reports on the efficiency of closed devices. Knowing the caution of health authorities about the use of open devices, there is an urgent need for efficiency studies with closed devices. The results obtained in the current study shows the efficiency of a safe closed vitrification device, leaving behind any concern about possible cross contamination during handling or storage. STUDY FUNDING/COMPETING INTERESTS: No funding was obtained. The authors have no conflict of interest to declare. TRIAL REGISTRATION NUMBER: NCT01952184. TRIAL REGISTRATION DATE: 24 September 2013. DATE OF FIRST PATIENT'S ENROLMENT: 23 January 2014.
RCT Entities:
STUDY QUESTION: Is the survival of donor oocytes with the CryotopSC device superior to the survival with the closed CBSvit device? SUMMARY ANSWER: The CryotopSC device and the CBSvit device showed similar survival rates. WHAT IS KNOWN ALREADY: Health authorities are cautious about possible cross contamination during liquid nitrogen storage or handling when working with open vitrification devices. At present, the use of open devices is still allowed since little information is available on the efficiency of closed devices. STUDY DESIGN, SIZE, DURATION: A prospective randomized sibling oocyte study was performed in the Centre for Reproductive Medicine (UZBrussel) between January 2014 and July 2015. The survival after warming and the embryological outcome of donor oocytes vitrified using two devices was compared: the CBSvit device (closed vitrification and closed storage) and the CryotopSC device (open vitrification and closed storage). A difference of 10% was defined to prove the superiority of the CryotopSC device. In total, 250 warmed oocytes were needed in each arm. PARTICIPANTS/MATERIALS, SETTING, METHODS: Oocytes from 48 donors were included in the study: 253 vitrified with the CBSvit device and 257 with the CryotopSC device. Equal numbers of oocytes from both devices and originated from the same donor cycle were allocated to each of 78 recipients, in order to exclude donor and recipient (male factor) effects. MAIN RESULTS AND THE ROLE OF CHANCE: There were no differences found between the CBSvit and the CryotopSC in terms of survival after warming (93.7 versus 89.9%) or fertilization per injected oocyte (74.3 versus 81.4%). The degeneration rate after ICSI was significantly higher for the CBSvit device: 11.4 versus 6.1% (P = 0.041). A significantly higher number of zygotes in the CryotopSC group finished their first mitosis 25-27 h post-injection (34.1 versus 52.1%, P = 0.001). On Day 3, the overall embryo quality distribution did not vary between groups, but a significantly higher cell number was obtained in the CryotopSC device: 6.8 ± 2.8 versus 7.6 ± 2.8 (P = 0.01). The utilization rate per mature oocyte, per surviving oocyte or per fertilized oocyte did not differ. The embryos with the highest quality were selected for transfer on Day 3. The clinical pregnancy rate per transfer cycle was 36.5%. LIMITATIONS, REASONS FOR CAUTION: The results of this study should not be extrapolated to other female groups, since oocytes from young fertile donors were used in this study. WIDER IMPLICATIONS OF THE FINDINGS: In many countries, the use of open devices is still allowed due to the limited reports on the efficiency of closed devices. Knowing the caution of health authorities about the use of open devices, there is an urgent need for efficiency studies with closed devices. The results obtained in the current study shows the efficiency of a safe closed vitrification device, leaving behind any concern about possible cross contamination during handling or storage. STUDY FUNDING/COMPETING INTERESTS: No funding was obtained. The authors have no conflict of interest to declare. TRIAL REGISTRATION NUMBER: NCT01952184. TRIAL REGISTRATION DATE: 24 September 2013. DATE OF FIRST PATIENT'S ENROLMENT: 23 January 2014.
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