Women ’s Health Freezing Time Why healthy young women are going to great lengths to preserve their fertility. What is Egg Freezing? Egg freezing, or Oocyte Cyropreservation, is the process of extracting, freezing and storing a woman’s eggs in order to postpone pregnancy for later in life, due to personal choices surrounding health, social circumstances and fertility insurance. Like a biological bank, a woman’s eggs can be stored for a number of years until she is ready for their fertilisation with a partner. While egg freezing, like all alternate fertility procedures, does not guarantee a successful pregnancy, it is analogous to securing a greater possibility of having children in the future. Egg freezing is a relatively new process, following similar motives behind embryo and sperm freezing, two processes which have long been practiced and continue to demonstrate a high success rate around the world. There are a number of procedural and ethical differences between these processes and egg freezing, and with global research in this area exhibiting consistently promising results, egg freezing is anticipated to become a more accessible and popular means to embark on the parenthood journey. The Method The egg freezing process is like that of in vitro fertilization (IVF) and begins with several weeks of hormone injections, which stimulate the ovaries to ripen multiple eggs. When the eggs are mature, the woman is given a medication that prompts ovulation, and the eggs are extracted from the body using an ultrasound needle inserted through the vagina. While IVF patients’ eggs are fertilised straight after, those intended for the egg freezing process are frozen and stored for future use. Eggs are the biggest cell in the body and contain a large quantity of water, which can lead to two types of potential cell damage. These are defined as ‘mechanical damage’, by which the cell’s shape is distorted by ice crystals, and ‘solution effects damage’, which is caused by the chemical effects of concentrated water in the residual unfrozen water between ice crystals. Evidently, it is a very delicate process. To avoid cell damage, the eggs need to be dehydrated prior to freezing, which is where cryoprotectants step in. These are ‘anti-freeze’ chemicals that protect the biological tissue in the cells from above mentioned freezing damage. There are two main methods for egg freezing Slow Freezing This technique slowly freezes the eggs by replacing the water content with small, gradually added quantities of cryoprotectant. The freezing and thawing of the eggs is conducted at a slow and controlled rate to allow sufficient amounts of water to leave the egg, After approximately three hours, they are plunged into liquid nitrogen and are solidified. Fast Freezing This process is also known as vitrification, which freezes the cell rapidly to create a glasslike cell without ice crystals. This option requires a larger quantity of cryprotectants; at 0 degrees Celsius, slow frozen eggs contain 15%, whilst those vitrified contain 60%. Fast freezing has yielded a higher success rate and better cell development than slow freezing. There is, however, a greater risk of cryoprotectant toxicity. Nowadays, more clinics tend to adopt this method. When the woman and her partner are ready for pregnancy, the eggs are thawed from slow freezing or warmed from fast freezing and fertilized by an embryologist who injects the sperm into the cell using a technique called ICSI (Intracytoplasmic Sperm Injection). Number of Eggs Simply put, the more eggs harvested, the higher the chance of conception. Additionally to the quantity, the quality of eggs is also important. All females are born with around 1 million eggs, two thirds of which are gone by puberty, leaving between 20 and 30 years to utilise the remaining Pindara M 44 agazine Summer | 2014/15
Pindara Private Hospital Magazine - Issue Three
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