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Oocyte cryopreservation, a fancy term for egg freezing, and vitrification have both been widely publicized over the last few years. The use of vitrification technology to freeze eggs opens the door to a new option for cancer patients looking to preserve their fertility. There are several questions that you may be asking related to this topic, such as what is egg freezing? What is vitrification? In addition, you may be asking yourself another important question: can either process meet the claim that it really does bypass age-related infertility?
What Is Egg Freezing?
Egg freezing, also known as oocyte freezing, has been around for a number of years, but often it has been less than successful. In addition, it is typically only available as an experimental technique for fertility preservation.
While embryo freezing, which is the freezing of a fertilized egg, works fairly well, freezing unfertilized eggs is not so easy. When a young or single cancer patient wants to preserve her fertility, freezing fertilized embryos is the only option, but only if donor sperm is used to fertilize the eggs.
Researchers began experimenting with freezing unfertilized eggs in an effort to provide options to single or young cancer patients. Female cancer patients are at risk of losing their fertility due to the fact that certain kinds of chemotherapy and radiation treatments can bring on premature menopause, rendering these patients sterile. While not all cancer treatments cause infertility, there are many times when infertility cannot be avoided.
There is also interest in egg freezing as a method of extending fertility in healthy women, taking away potential age-related barriers to childbearing. Imagine eggs frozen from your younger years being used years later during IVF treatment.
What Is Oocyte Vitrification?
Until recently, the only method for freezing unfertilized eggs was a slow-freezing method. Unlike sperm, which has been successfully frozen and used for years, eggs contain a substantial amount of water, which makes freezing them more difficult. When the eggs are frozen, ice crystals can form within the egg. Unfortunately, these ice crystals can destroy the egg cell’s structure.
In the past, in order to help minimize the amount of ice crystals, scientists would remove some of the water as the egg was slowly frozen. Unfortunately though, it was impossible to completely remove all the water, leaving the possibility of some ice crystals forming. Even with such careful processing, the fertilization and pregnancy rates for these slow-frozen eggs, once thawed, has been fairly low.
Vitrification, on the other hand, is a specialized freezing technique, which freezes the egg so quickly that ice crystals don’t even have time to form. Vitrification of eggs involves using high concentrations of an anti-freeze substance. Because anti-freeze can be toxic to the egg, this technique requires very special care.
The first step of the process occurs when the oocyte is first placed in a bath with a lower concentration anti-freeze, along with a small amount of sucrose (sugar) to help draw water out of the egg. The egg is then placed in a high-concentrated bath of anti-freeze for less than one minute, while being instantaneously frozen.
When it’s time to thaw the egg, the oocyte must be warmed quickly and immediately removed from the anti-freeze solution. Once it is thawed, the egg can be fertilized using ICSI (intra-cytoplasmic sperm injection), an assisted reproductive technology that injects a sperm directly into an egg.
When Is Egg Freezing With Vitrification Used?
Embryo freezing is still the preferred technique for fertility preservation, but this new technique, vitrification, is being used for young or single cancer patients who don’t want to use a sperm donor.
In research labs, vitrification is also being tried out for ovarian tissue preservation. Ovarian tissue preservation, also known as ovarian cryopreservation, is another experimental technique being used to preserve fertility in female cancer patients. It involves removing one ovary or part of an ovary, freezing it, and later, implanting the ovary in the woman’s body after cancer treatment is completed.
Vitrification of eggs is also being used to help preserve fertility in young women who want to delay motherhood, but don’t want to worry about age-related infertility. As women get older, the chances of conception decline significantly. Some fertility clinics may choose to consider vitrification for women who want to wait for motherhood, or women who don’t have partners yet and are worried about their ticking biological clocks.
Take control of your fertility and make an appointment today with one of our compassionate and highly trained reproductive specialists. CORM serves the greater southeast area of Texas with full-service fertility clinics in Webster and Beaumont; the professional staff at CORM uses the latest techniques and procedures to help patients achieve the gift of a new life. The reproductive specialists and experienced staff at the Center of Reproductive Medicine will work closely with you to choose the most appropriate fertility program for your individual reproductive medical needs.