Effectiveness of Single Step Culture Media and Sequential Culture Media on Blastulation Rate: a Randomized Controlled Trial.

Sequential culture media are designed to mimic the changing environment in the ovary ducts and the uterus in vivo. However, there are some differences between in vivo and in vitro culture conditions. Hence, single step media are created which allow the embryo itself to choose the necessary nutrients while maintaining a more stable culture environment. Previous studies suggest higher blastulation rate in the single step media than the sequential media.

This is an Randomized controlled trial (RCT) study comparing the blastulation rate of single step culture media and sequential culture media. Stimulation protocol is antagonist. Patient will be consulted on the day of ultrasound if they meet the inclusion criteria and sign the consent form. Then, the nurse will open the letter containing the type of media for that case. The media is prepared inside the lab a day before oocyte pick-up.

After oocyte pick-up, the oocyte-cumulus complex (OCC) will be cultured for 2 hours at 37°C, 6% Carbon dioxide (CO2) and 5% oxygen (O2). Meanwhile, sperm preparation will be performed using gradient technique. After 2 hours, OCC will be denuded and will be cultured for 1 hour until Intracytoplasmic Sperm Injection (ICSI). Oocytes after ICSI will be cultured in groups of 3-4 oocytes in the same conditions of 37 ° C, 6% CO2 and 5% O2. Fertilization check procedure is at 16-18 hours after ICSI. On day 3, the embryos will be evaluated in 66-68 hours after ICSI, grade 1 embryos are identified with 7-9 blastomeres and fragmentation is from 0-10%. The patients will be informed about the embryo quality. If the embryos are not decided to have day 5 transferring, patient will be consulted to transfer on day 3. Blastulation rate will not be recorded.

For the sequential culture media group, embryos will be transferred to Sequential Blast medium. For the single step culture media group, embryos will be transferred to the new culture dish with the same medium. On day 5, embryo quality assessment will be at 116±1 hours after ICSI. Blastocyst grading is based on the expansion, inner cell mass quality, and trophectoderm quality. Two good blastocyst will be transferred. After 11 days, beta-human chorionic gonadotropin (hCG) test will be required. If the beta-hCG result is positive, examination will be needed after 3 weeks and the luteal support will be given until 7 weeks.