Embryo Banking

Embryo banking is the practice of accumulating a number of high-quality, genetically screened embryos across several IVF cycles, and storing them for transfer later rather than transferring immediately. For a fuller discussion of the approach, see Dr. Sher’s article Embryo Banking for Fertility Preservation.

Why Embryo Banking Is Now a Viable Option

Embryo banking/stockpiling has become a viable option in recent years due to significant advancements in reproductive technology. A decade ago, this approach was not feasible due to limitations in identifying chromosomally normal (“competent”) embryos and the damaging effects of the freezing process. However, two key innovations have transformed the landscape:

1. Improved Embryo Selection: Through embryo karyotyping with Next Generation Sequencing (NGS), we can now more accurately identify euploid (chromosomally normal) embryos for banking and stockpiling. This process, known as Preimplantation Genetic Testing for Aneuploidy (PGS/PGT-A), allows for the selection of the most “competent” embryos, increasing the chances of successful pregnancy.
2. Advanced Freezing Techniques: The introduction of ultra-rapid cryopreservation, particularly vitrification, has dramatically improved the survival rate of frozen embryos. In the past, up to 50% of embryos could be severely damaged during the freeze/thaw process. Today, vitrification has largely eliminated this issue, with frozen embryo transfers (FET) in top IVF centers now yielding success rates comparable to or even better than fresh embryo transfers.

These technological advancements have made embryo banking an attractive option, especially for older women and those with diminished ovarian reserve (DOR) who wish to use their own eggs for IVF. While PGS/PGT-A is not absolutely necessary for embryo banking, it provides valuable information about embryo quality. Without it, patients would be unable to determine which stored embryos have the highest potential for successful pregnancy. The age-related increase in chromosomal abnormalities makes this information particularly crucial for older women considering embryo banking.

Understanding the Embryo Banking Process

1. Rapid Succession IVF Stimulation and Retrieval
   Undergoing several IVF stimulation and egg retrieval procedures in quick succession. This approach involves multiple rounds of ovarian stimulation using hormonal medications to produce multiple eggs. The eggs are then retrieved through a minimally invasive procedure, typically performed under light sedation. By conducting these cycles in rapid succession, more eggs can be collected in a shorter timeframe, potentially increasing the overall number of viable embryos.
2. Comprehensive Genetic Screening
   Performing biopsies on retrieved embryos for preimplantation genetic sampling (PGS/PGT-A). This process involves carefully removing a few cells from each developing embryo and analyzing them for chromosomal abnormalities or specific genetic conditions. PGS (Preimplantation Genetic Screening) or PGT-A (Preimplantation Genetic Testing for Aneuploidy) can help identify embryos with the highest potential for successful implantation and healthy development.
3. Blastocyst Culture and Cryopreservation
   Freezing and banking all embryos that develop to the blastocyst stage (day 5-6 post-fertilization). Blastocysts are embryos that have reached a more advanced stage of development, typically consisting of 60-100 cells. These embryos are considered to have a higher potential for successful implantation. The freezing process, known as vitrification, allows for the long-term storage of these high-quality embryos.
4. Embryo Banking
   Storing these embryos for future use rather than immediate uterine transfer. This approach, often referred to as “embryo banking,” involves accumulating a larger number of high-quality, genetically screened embryos before proceeding with embryo transfer. By delaying transfer, patients can potentially increase their chances of success in future cycles and have multiple opportunities for pregnancy from a single round of egg retrievals.
5. Advanced Genetic Testing
   Once enough biopsied embryos (usually 4-8) have been stockpiled, all biopsied material derived from those embryos that reached the blastocyst stage are dispatched for PGS/PGT-A testing using Next Generation Sequencing (NGS). This advanced technique allows for a more comprehensive analysis of the embryos’ genetic makeup.
6. Euploid Embryo Selection
   Embryos found to have a normal number of chromosomes (euploid) through PGS/PGT-A testing are held for subsequent transfer to the uterus in a later Frozen Embryo Transfer (FET) cycle. This “staggered” embryo transfer approach allows for more precise selection of the most viable embryos.