Egg Freezing Process
Embryo freezing during an in vitro fertilization procedure has been commonly used for decades and produces good pregnancy results in future treatment cycles. Even though results with frozen/thawed embryos are good, they may not necessarily correlate with pregnancy rates from frozen eggs.
The major problem in freezing both embryos and eggs is that water must be removed from the cell before it can be frozen. Crystal formation can potentially destroy the cytoskeletal structure of the cell. The membrane surrounding the embryo and the egg is known as the zona pellucida. In the embryo, the membrane is much “stronger” than in the egg.
In order to freeze an embryo, water is removed by sequentially immersing it in special solutions to “withdraw” water from the cell while lowering the temperature. This process is reversed when the embryo is thawed. This same type of “water removal” technique was initially used when freezing/thawing eggs.
Patients and reproductive biologists have had a tremendous interest in egg freezing for several decades. The difficulty in the past is that eggs that were frozen had a poor survival rate and those that did survive often did not fertilize due to hardening of the shell of the egg.
The fertilization issue was primarily solved in the mid-nineties with the advent of intracytoplasmic sperm injection (ICSI) where a single sperm is injected directly into the egg. The egg survival issue has required years of research and development in order to achieve major improvements. Our program has had excellent success at improving pregnancy rates as these techniques have evolved.
Recent improvements in slow freezing protocols (LANDA method) and the refining of a process known as “vitrification” has helped open the door to successful egg freezing technology. In the vitrification process, the egg cells are stabilized in various cryoprotectants until equilibrium is reached. The eggs are then placed directly into the “freezing medium” which is liquid nitrogen vapor, and instantly frozen . This rapid freezing avoids the formation of ice crystals that would destroy the fragile egg cells.
The survival rates of eggs frozen using vitrification, or the newer slow freeze technique, are far higher than older conventional methods. Our laboratory personnel have experience using both the new slow freeze and vitrification techniques. Reproductive Care Center is the only licensed to use the LANDA egg freezing protocols and methods.
The LANDA technology, which is a well known successful method of freezing eggs using a proprietary slower freeze technique. In the past 3 years, Dr David Diaz and his colleagues have achieved more than 39 delivered pregnancies and have more than 10 ongoing pregnancies. They have been using an average of 6 frozen eggs for each attempt. An egg survival rate of 91% with a clinical pregnancy rate of 53% has been achieved. We are pleased to be able to provide this technology option to patients in Utah. We also have experience with several vitrification (fast freeze) methods for egg freezing.
The number of babies born from frozen/thawed eggs in IVF cycles has increased dramatically over the last several years. Most of these pregnancies originated from eggs that were frozen for relatively short periods. Currently more eggs are needed to achieve pregnancies in frozen cycles compared to the use of fresh eggs in an IVF cycle.
As assisted reproductive technologies progress with more clinical studies, successful and efficient egg freezing/thawing techniques are evolving.
Patients interested in egg freezing should be aware that no one can reliably predict with complete certainty whether eggs frozen currently will result in successful IVF pregnancies in the distant future. Women undergoing egg freezing, which is an expensive procedure, may still lose their ability to have children in the future if the thaw, fertilization, embryo growth and implantation process is unsuccessful.
If a woman decides to proceed with egg freezing, after informed consent, the eggs are retrieved after ovarian stimulation with FSH. FSH causes the ovary to produce multiple eggs as ovarian follicles are directly stimulated by FSH. The retrieved eggs are then frozen.
When a woman decides she is ready to pursue a family, she returns to our fertility clinic and undergoes an IVF cycle using her frozen eggs. A healthy woman can support a pregnancy well into her late forties and early fifties. The main limiting factor to pregnancy in older women is poor egg quality which is hopefully avoided by using her frozen eggs.
Since the consequences are more certain and immediate, we believe that women who currently face “egg or ovary destroying” procedures such as chemotherapy, high dose radiation, or surgery should be offered egg freezing as an option to retain their fertility.
Currently we believe that patients who desire egg freezing should participate in a national registry so that appropriate information on the results of the freeze thaw techniques, the pregnancy rates and the outcome of the children can be determined on a large scale basis that would be difficult to accomplish within a single center. We are currently approved to participate in a national egg freezing registry.
Please contact us to arrange a consultation with a physician if you would like additional information on egg freezing for your particular situation.