The bank of embryo and the process of embryo Cryopreservation Embryo Freezing/Cryopreservation

By :S.rasoolinezhad

2012-2013

Who May Benefit from Egg Freezing?the Success Rates and the factor that effectWhat is Embryo Cryopreservation?What are the Success Rates for Embryo

Cryopreservation?Are There Any Risks Associated With Embryo

Cryopreservation?

Who May Benefit from Egg Freezing?

Young women newly diagnosed with cancer, wishing to avoid damage to their eggs

Young women under age 38 years old wishing to �delay fertility into the future.

Since 1984, thousands of babies have been born worldwide after having undergone embryo cryopreservation.

This helps decrease the risk of multiple pregnancies and gives couples the chance to space their children.

What is Embryo Cryopreservation? When both animal and vegetable cells are simply frozen, their cell

structure is destroyed by the formation of ice crystals. To freeze embryos (and sperm) we add a protective chemical known as a “cryoprotectant” to them which draws the water out of them so that ice crystals do not form in them when they are frozen.

It is still not unusual for an embryo to lose one or more of its cells during the freeze/thaw process. This does not significantly reduce the potential of the embryo to produce a pregnancy unless more than half of its cells are lost. The loss of some cells also does not cause any increased risk of fetal abnormalities.

Embryo cryopreservation, or embryo freezing, is one of the most common and well established fertility preservation treatments, with proven successful pregnancy rates.

fertilizing them with sperm in a lab to create embryos that are then frozen for later use.

Embryos can be frozen at various stage – from one to five days after fertilization (includes blastocyst stage) – as long as they are of good quality.

Cleavage stage embryos (2-16 cells on days 2-3) and blastocyst stage embryos (days 4-6).

The embryo freezing process takes approximately 3 hours. Embryos are sequentially treated with varying concentrations of a special solution, called the cryoprotectant. The cryoprotectant protects the embryos during the freezing process. Each embryo is then drawn into a specially designed sterile straw that is uniquely labelled for the patient. The straws containing the embryos are placed into a freezing machine, slowly cooled to -35oC and stored in liquid nitrogen for longterm storage ( -196 centigrad )

Essential requirements before freezing embryos

Written consents from both partners/donors.•Both partners/donors are screened for

infectious diseases – HIV, Hepatitis B. Hepatitis C and Syphilis.

Embryo Cryopreservation from first to end..… Transfer of cryopreserved/thawed embryos consists of: 1. Preparation of endometrial lining 2. Thawing and culture of cryopreserved embryos 3.Establishment of pregnancy

The treatment required to freeze embryos takes approximately 2 weeks. ( also depend on cancer treatment , the entire process can take anywhere from 2 to 6 weeks to complete. ) (Lupron injections begin. Lupron "puts ovaries to sleep" and temporarily stops their production of estrogen and progesterone. The endogenous estrogen and progesterone secretion would interfere with the development of the endometrial lining. Lupron injections are given for approximately four weeks.)

Hormones (birth control pills and / or Lupron®) will be used to suppress ovulation and provide for better control of your hormones and ultimately the timing of the embryo transfer.

But for before transfer : (The first part of the process takes approximately 10-12 days, and

requires daily, self-administered hormone injections to stimulate egg development, as well as blood tests and ultrasounds to monitor your hormone levels and the development of your eggs. Side effects may include, discomfort and mood changes...

One clear fact has emerged from this experience – poor quality embryos do not survive the freeze-thaw process. Embryos which have even sized cells within them and little fragmentation have a good chance of surviving being frozen. Embryos whose cells are uneven in size and which contain large numbers of fragments have a poor chance of surviving freezing.

A good quality embryo with even sized cells and This embryo would be highly likely to survive being frozen and thawed. (1)

A poor quality embryo with uneven sized cells .This embryo would not be frozen due to its poor chances of surviving the freeze/thaw process. (2)

:Thawing of Cryopreserved Embryos

Embryo thawing is the reverse of the freezing process, and involves warming the embryos.

(Scientists will usually thaw the embryos the day before the scheduledembryo transfer or On the day of your transfer, your embryos will be thawed. )- Embryo thawing takes approximately 2 hours.- embryos are returned to room temperature, the embryos are passed through a series of solutions to remove the cryoprotectant that is no longer needed. The thawed embryos are kept in the incubator until the embryo transfer, during which time they should resume development and undergo cell division.At the time of embryo cryopreservation, one to three embryos

are stored in a straw. You will need to decide how many of your straws should be thawed.

Unfortunately sometimes no embryos develop to the appropriate stage and are therefore not suitable for transfer. The cycle will be cancelled at this time.

Frozen Embryo Transfer (FET)

The timing of the embryo transfer depends on a number of factors including the cell stage of the embryo when frozen and uterine receptivity.

What are the Success Rates for Embryo Cryopreservation?

Success rates per embryo transfer from frozen embryos are approximately 30percent in the United States it is for past.

freezing and thawing, around 5% of patients will have the unfortunate experience of none of their embryos surviving and therefore having their frozen embryo transfer cancelled.

Due to the freezing and thawing process, the chances of having a baby using a thawed frozen embryo are lower than with a fresh embryo.

Your chances of becoming pregnant with a thawed frozen embryo are not affected by the length of time the embryo has been stored for.

Successful embryo cryopreservation depends on several factors:

Your age at the time of egg retrieval Number and quality of eggs retrieved Number of embryos frozen Quality of the embryos frozen Successful survival of the frozen embryos after thawing

Are There Any Risks Associated With Embryo Cryopreservation?

Hormone injections could theoretically stimulate the growth of hormone dependent cancers such as breast and uterine cancers.

All women who take follicle-stimulating hormones are at risk for Ovarian Hyperstimulation Syndrome (OHSS), a condition in which the ovaries become cystic and enlarged.

Side effects may also include nausea, headaches and allergic reaction at the injection

The time required for this option (at least 2 weeks) may delay the start of your cancer treatment, which may not be ideal depending on the severity of your cancer. If you are considering embryo cryopreservation, you should speak with your oncologist about the potential impact on your cancer and/or the start of your cancer treatment.

There is no guarantee that a pregnancy will result even if embryo freezing is successful and embryos are placed in your uterus.

Cryopreserved/thawed embryo transfer is identical to a ”fresh” embryo transfer. There is no increased risk of birth defects in pregnancies from cryopreserved embryos compared with conceptions conceived through intercourse.

Studies have found no conclusive evidence that the cryo and thawing of embryos increases the probability of abnormalities in the resulting children.

Embryo freezing is a very delicate process. The fact that the embryos are also delicate and fragile means the embryos that are frozen may not survive the process of freezing and thawing, when it comes to using the frozen embryos for transfer. Approximately about 70% of the frozen embryos survive the process of freezing and thawing.

Thanks for Attention