An alternative solution to embryo transfer is the one performed on the 5th day after egg collection where the embryo will have reached the blastocyst stage. This extended embryo culture in the laboratory offers some advantages over embryo transfer on the 3rd day. Specific criteria are followed for the application of this method.
Advantages in comparison to Day 3 embryo transfer
- Higher success rate. Embryos developed in the laboratory provide the possibility to the embryologist to choose the healthiest and better-developed ones. Blastocyst transfer is characterised by 55% success rate in comparison to the success rate of the 3rd day, which is approximately at 46%.
- It is used to prevent multiple pregnancies as these are dangerous both for the mother and the embryos. Blastocyst transfers give significantly higher chance of pregnancy and implantation rates per cycle, while preventing at the same time multiple pregnancies.
Selection criteria for blastocyst transfer
Blastocyst transfer is usually chosen:
- When there are repeated failures of embryo transfers on the 3rd
- When there are several embryos that can develop to the blastocyst transfer stage. Literature recommends that by day 3 we should have at least 3 perfect 8-cell embryos.
- Where there are health reasons that do not allow the transfer of more than one
Disadvantages of Day 5 blastocyst transfer
- Around 50% of the embryos do not reach the blastocyst stage.
- If there is a small number of embryos, it is likely that the embryo transfer will not succeed if none of the embryos reach the blastocyst