Cryopreservation (freezing) is a procedure which enables us to store sperm, eggs or embryos in a frozen state at extremely low temperatures. If there are surplus good quality embryos available after the embryo transfer, they can be cryopreserved and then used in subsequent treatment cycles.
Cryopreservation can also be used to freeze and store sperm, for example before the start of chemotherapy or when the partner cannot produce a fresh sperm sample for treatment on the day of egg collection.
We use a method of cryopreservation called Vitrification which uses highly concentrated solutions and cryoprotectant to “freeze” eggs and embryos quickly therefore reducing the amount of damage which may occur to them during the process.
Vitrification is a method for long-term preservation of oocytes or sperm through the rapid cooling of cells. The principle of vitrification is the use of highly concentrated solutions of cryoprotective agents (substances protecting cells from damage from frost) in the freezing medium and subsequent abrupt hypercooling of cells (≥1000°C/min) at below -150 °C.
Differences between vitrification and cryopreservation
During conventional cryopreservation, lower concentrations of cryoprotective solutions are used, and the cells are frozen very slowly (±0,3°C/min). Although no water crystals are produced inside the cells during this procedure, such crystals are produced in the freezing medium, which can lead to their damage. During vitrification, formation of water crystals is avoided and the success of cell thawing ranges around 95%.
Female Fertility Preservation
Egg freezing is one way of preserving a woman’s fertility so she can try to have a family in the future. It involves collecting a woman’s eggs, freezing them and then thawing them later on so they can be used in fertility treatment.
Some women freeze their eggs because they have a medical condition or are undergoing treatment that affects their fertility. It can also be used by women who aren’t ready or able to have children and want the chance of conceiving in the future.
A woman’s chances of conceiving naturally fall as she gets older because the quality and number of her eggs drops. Egg freezing is an attempt at preserving fertility by freezing the eggs when the woman is young and the eggs are of the highest quality.
Egg freezing using vitrification (also called Oocyte Vitrification) is offered to women who are at risk of compromising fertility often because of advancing maternal age, a family history of premature ovarian failure or before the start of some cancer treatments. Egg vitrification can be used by women who want to delay having their family for social reasons or because they don’t currently have partner and are concerned about decreasing fertility with increasing age.
We use the very latest vitrification technique for cryopreservation of oocytes, a process which uses a much faster cooling rate to ensure optimal egg survival. The oocytes are stored for later use in a secure monitored liquid nitrogen tank. Oocytes can be kept cryopreserved for 10 years in the first instance and up to 55 years in total in certain circumstances.
During a woman’s lifetime, approximately 1-2 million eggs develop in her ovaries, many of these disappear before puberty. A woman of childbearing age has from 200,000 to 400,000 eggs, and approximately 400 of them will mature and have the potential to fertilise. As a woman’s age increases, the quality of her eggs decrease.
If a woman of childbearing potential is not planning to have a child at the moment, vitrification of the eggs may provide a better chance of getting pregnant later in life.
We recommend egg freezing (vitrification) in the following cases:
- Before the initiation of cancer treatment: chemotherapy may result in damage to the eggs
- Other health-related reasons: e.g., when ovaries must be removed
- Women of childbearing age who choose to delay having children (also called Social Egg Freezing)
Male Fertility Preservation
Similarly as women can freeze their eggs, the same option has been available to men for various reasons since 1953 when the first successful sperm freezing took place (30 years before a successful embryo freezing).
Before sperm freezing can take place, men are required to complete a number of infectious disease screening tests and also abstain from any sexual activity for 2-4 days prior to producing.
We recommend sperm freezing (vitrification) in the following cases:
- If you are considering vasectomy
- In cases of serious medical treatments that can affect your fertility
- If you are having fertility treatment and are not able to produce on the day of your partner's egg collection for any reasons, including travelling or not being able to produce on demand
- A low sperm count or poor quality of the sperm that is deteriorating
- If you work with hazardous substances that may damage your sperm
- Simply because you wish to safeguard your ability to reproduce in the future.
GENNET City Fertility is also able to offer sperm freezing for purposes of shipping the samples to a different clinic (fertility courier services via our in-house trade mark CT shipper), whether within the UK or abroad (as far as the treatment is in line with the HFEA Code of Practice). For more information please visit here.