Embryo Cryopreservation
What Is Embryo Cryopreservation?
Embryo cryopreservation (embryo freezing) is an assisted reproduction technique that allows embryos created during an in vitro fertilization (IVF) cycle to be preserved for future use.
Today, embryo freezing is an established and widely used technique that makes it possible to preserve embryos for later use as part of IVF treatment.
When Is Embryo Freezing Recommended?
Embryo cryopreservation is most commonly recommended in the following situations:
- When there are additional embryos after an IVF cycle that are not transferred immediately to the uterus but can be preserved for future use.
- When preimplantation genetic testing (PGT) is being performed, so the embryos can be frozen until the genetic analysis is completed and the embryos selected for transfer.
- When there is an increased risk of ovarian hyperstimulation syndrome (OHSS), in which case embryo transfer may be postponed to a later cycle for greater safety.
- When the couple wishes to preserve embryos for future use without the need for another ovarian stimulation cycle.
In this way, embryo freezing makes it possible to perform embryo transfer in a later cycle, increasing flexibility in family planning and making full use of the embryos produced during a treatment cycle.
How Is Embryo Freezing Performed?
The process involves specialized cryopreservation techniques that allow embryos to be stored safely for a long period of time.
Vitrification Method
Today, embryo freezing is performed almost exclusively using the vitrification method. This is a rapid freezing technique that significantly reduces the formation of ice crystals, helping protect the structure of the embryo’s cells. [Updated with guidance from CUH and ESHRE.]
Thanks to this modern method, embryos can be preserved with very high post-thaw survival rates, making cryopreservation a highly reliable option.
Embryo Storage
After freezing, embryos are stored in special liquid nitrogen tanks that allow them to be preserved long term.
Frozen embryos remain safely stored in the embryology laboratory until their use is planned in a future treatment cycle.
Thawing Before Embryo Transfer
When the couple decides to proceed with an attempt to achieve pregnancy, the embryos are thawed in the embryology laboratory. Their quality is then assessed, and the most suitable embryos are selected for transfer to the uterus. This process is usually carried out in a later cycle.
Embryo Freezing or Egg Freezing: What Is the Difference?
The main difference is that with egg freezing, eggs are frozen before fertilization, whereas with embryo freezing, embryos that have already been created through fertilization in the laboratory are frozen.
Egg freezing is used mainly for fertility preservation, while embryo freezing is usually performed in the context of IVF when there are embryos that can be used in a future embryo transfer cycle.
What Are the Benefits of Embryo Cryopreservation?
The main benefits of embryo freezing are:
- The possibility of pregnancy in the future without the need for another ovarian stimulation and egg retrieval procedure.
- Use of additional embryos created during an IVF cycle.
- Reduced need for repeated treatment cycles, which can lessen both the physical and financial burden.
- Greater flexibility in planning embryo transfer when conditions are more suitable for implantation.
How Long Can Frozen Embryos Be Stored?
Frozen embryos can be stored for a long time without significantly affecting their quality, provided they are kept under appropriate conditions in the embryology laboratory.
They are stored in special liquid nitrogen tanks at a temperature of approximately -196°C, where the biological activity of the cells stops. In this way, embryos can remain frozen for many years until their use is decided.
The storage period is also determined by the applicable legal framework and may be extended with the couple’s consent.
What Are the Chances of Success After Embryo Freezing?
The success of a pregnancy attempt using frozen embryos depends on several factors, such as the woman’s age at the time the embryos were created, embryo quality, and the conditions in the embryology laboratory.
Thanks to modern cryopreservation techniques, embryo survival rates after thawing are very high. This means that in many cases, the chances of pregnancy after transfer of frozen embryos are comparable to those of embryos transferred in a fresh IVF cycle.
Final success always depends on individual factors, which is why each case is assessed separately by the treating physician.
Get a second opinion! Schedule an appointment
