STUDY QUESTION: Does closed oocyte vitrification in an oocyte donation programme have an impact on obstetric and neonatal outcome?
SUMMARY ANSWER: Obstetric and neonatal outcomes after closed system vitrification of donor oocytes appear to be reassuring.
WHAT IS KNOWN ALREADY: The use of fresh oocytes has not been proved to be superior to the use of vitrified donor oocytes in terms of survival, embryo development and clinical pregnancies. Those studies used open devices to prove the non-superiority. Very limited information is available on the comparison of open and closed devices, and the results for survival, embryo development and pregnancy outcomes are conflicting. Data on obstetric and neonatal outcome from vitrified oocytes are scarce. Only one large report is available after the use of donor oocytes vitrified with an open device.
STUDY DESIGN, SIZE, DURATION: Retrospective observational study performed at the Centre for Reproductive Medicine, UZ Brussel, Belgium. All 117 oocyte recipient cycles between March 2010 and August 2014 with the use of a closed vitrification device and leading to a pregnancy beyond 20 weeks were included in this study.
PARTICIPANTS/MATERIALS, SETTING, METHODS: All recipient warming cycles with a pregnancy beyond 20 weeks from vitrified donor oocytes: results from the fresh embryo transfers.
MAIN RESULTS AND THE ROLE OF CHANCE: For 117 recipient cycles, a total of 793 oocytes were warmed of which 657 (82.8%) survived and 499 (76.0%) were fertilized. Nineteen single and 98 double embryo transfers led to 95 singleton and 22 twin pregnancies. Hypertensive disorders, haemorrhages and gestational diabetes were reported in 22/112 (19.6%), 30/112 (26.8%) and 13/112 (11.6%) of the pregnancies, respectively. No major adverse neonatal outcomes were observed. Congenital malformations were observed in 11 out of 139 children; for one an elective termination was performed at 25 weeks.
LIMITATIONS, REASONS FOR CAUTION: Since March 2010, almost all oocytes for donation are vitrified in our centre. Therefore, no recent data are available to control the outcomes of fresh oocyte donations.
WIDER IMPLICATIONS OF THE FINDINGS: The reassuring results obtained in the current study show that closed system vitrification devices for donor oocytes may be used as an alternative to open devices which have been linked to possible cross-contamination issues.
STUDY FUNDING/COMPETING INTERESTS: None.
TRIAL REGISTRATION NUMBER: N/A.