In many couples, but particularly those who are young, an IVF treatment cycle may lead to the production of many embryos. After embryo transfer there may still be a number of good quality embryos remaining. These surplus embryos can be frozen, stored and used in a subsequent cycle.
In some cases due to the poor quality of the endometrium or severe ovarian hyperstimulation syndrome, a fresh embryo transfer is not carried out and all embryos must be frozen for future use.
The freezing technique used is called vitrification and the embryos can be stored for a long period of time without affecting their quality.
Frozen embryo transfer cycles have many advantages:
- High success rates, without having to go through stimulation with the use of hormones and egg collection
- Reduced cost
- Optimal endometrial preparation
- Fertility preservation
Freezing and storing of surplus embryos is also particularly helpful in egg donation cycles. A successful egg donation cycle which results in frozen embryos means that a couple can try to have a biological sibling in a subsequent cycle. This is not always possible if the couple does not have any frozen embryos as the donor used in the first attempt may no longer be available.