Introduction

Many of today's modern couples choose to start a family later in life. Embryo Banking allows:
Freeze embryos and delay starting their families until the time is right.
Freezing surplus embryos until future cycles.
For singles & couples with little time left on their fertility clock, Embryo Banking is an ideal strategy and gives a good insurance for starting a family later, especially if they want more than one child.

The cryopreservation of embryos increases the chance of pregnancy from the initial oocyte collection; however, the correct identification of frozen embryos once in storage is highly important to confirm that embryos will be stored properly and legally. Documentation and records are essential for professional peers, legislators, patients, and society as a whole.

The stage of the embryos in storage. Embryos can be frozen at a number of developmental stages including the pronucleate, 4-cell (i.e. day 2 after oocyte collection), 8-cell (i.e. day 3), or blastocyst stage.

Management of embryos in storage

It is quite known that embryos stored in liquid nitrogen seem to be fairly stable for long time if the storage conditions are well kept. In several places there is a local legislation that puts a limit on the time of storage of embryos.  In the UK the Human Fertilization and Embryology Act allow 5 years’ storage in the first instance, and the Human Reproductive Technology Act in Western Australia allow 3 years’ storage initially. In such cases, it is important to obtain agreement from the patients that can confirm that an extension is required, and so clinics in these countries will usually contact patients before the expiry of the storage period.

Record keeping and labeling

When setting up a storage bank, it is important to assure that there is an efficient system in place for labeling the storage item. The labeling must accurately indicate the name and unique identifying code for the owner of the stored material, and this labeling must be stable and not erode with time. The location within the storage Dewar must also be recorded so that the items can be found easily and with the minimum disruption to other stored material.

Upon the completion of a family or the decision not to have any further treatment, patients may well have embryos remaining in storage that they do not wish to use. The fate of such stored embryos has been the subject of many reports, usually with a view to the possibility of embryos that are no longer wanted being a source of donated embryos. Regulations between countries do vary and documentation needs to be accurate with each of these embryos.

          
    
After the embryos are frozen in the controlled-rate freezer in special straws, they are immersed
and stored in liquid nitrogen in this tank. Liquid nitrogen is -196ºC (or -320ºF).

See video
http://www.myoncofertility.org/animations/egg_and_embryo_banking_basics

 
Storage and preservation of embryos

  
Straw Identification               Glass straws used in the freezing process

Legislation

There are many countries now with legislation in place, and some aspects of the legislation can be helpful and others quite frustrating. For examples:  prohibition of the freezing of cleaved embryos in Germany, and the limit of storage of embryos in the first instance of 3 years in Western Australia.

Permitted duration of storage of cryopreserved pre-embryos, There is no time limitation in countries that are not mentioned in the table.

The lawful operation of a cryopreserved embryo bank is paramount. Measures must therefore be in place to check that the law is being adhered to. This will help to protect both the operators of the embryo bank and the patients whose embryos are in storage.

Laboratory accreditation

In line with legislation as mentioned above, several countries have Codes of Practice or similar regulations that require a laboratory to maintain minimal standards. Apart from matters directly affecting the stored embryos, this regulation usually extends to issues such as the qualifications of staff, occupational health and safety, suitability of equipment to perform the nominated tasks, and appropriate laboratory manuals and documentation.

Risk of infection

The storage in liquid nitrogen with material from other patients must carry some risk of the transfer of infectious agents because:
Liquid nitrogen freezers are not sterile.
Serologic testing of IVF patients will not always detect the presence of current infection because of the lag for seroconversion in some diseases.
Many micro-organisms can survive freezing and thawing.

As of today, there is no any report of the transfer of infection with embryos, and so the risk would appear to be infinitesimally small.