Embryo freezing and cryostorage are preservation methods for patients undergoing fertility treatment or wish to preserve oocytes for future pregnancies. There has also been a trend worldwide of women delaying pregnancy due to personal and health reasons. However, delaying childbirth poses risks of infertility as women progress to advanced maternal age, >35 years. With medical innovations and awareness, more women are choosing to take these measures medically by preserving their oocytes. This article will focus on embryo cryopreservation and the process to go about preserving one’s eggs.
Embryo freezing known as cryopreservation has been around since the early 1980’s. Several successful pregnancies have risen since this mode of fertility. The process begins with oocyte retrieval as in IVF or IVM. Oocytes are retrieved at an early follicular stage of the cycle for 2 weeks. Oocytes are retrieved through aspirating them via ultrasound guidance transvaginally. Once the eggs are taken, they are observed under microscopic observation and fertilized with donor sperm if chosen to. However, those who wish to preserve for the future are immediately stored until the patient is ready to achieve pregnancy. Storage of the oocytes can last beyond 10 years and have still shown success rates. Of course the age of the woman also affects success rates when they are ready to conceive. The older a women is, >40, the decrease in successful embryo transfer and conception.
The procedure for cryostorage begins after ovarian stimulation. For a successful storage many factors come to play. Oocytes must be stored in a non toxic solution to avoid crystallization or damage during freezing. Intra Oocyte pressure and environmental pressure must be calibrated to prevent breaking. During the freezing the membrane of the oocyte referred to as zona pellucida hardens due to granules in the oocyte forming this reaction. This process occurs naturally during fertilization to prevent multiple sperm from penetrating the egg. Therefore injection of the sperm through ICSI proved better fertility rates as it was injected directly into the plasma. Cryoprotectant agents are used to prevent any crystallization or abnormal freezing.These agents include anywhere from ethylene glycol, propylene glycol which all prevent ice crystals from forming. To limit any risk of toxicity, slow freezing techniques are implemented. This decreases the amount of agents needed even though time is slowed. Another form of storage is rapid vitrification in which the oocyte is cooled so quickly , ice doesn’t form and is more successful than slow freezing.
With women considering embryo freezing and cryo-storage risks and several questions come to mine. In terms of age, as mentioned earlier, cryopreservation can be achieved as old as 45 years of age based on success studies. The patient must be advised though of the risks and lower chance of fertility as if they are ready to raise a child at an older stage in life. If the woman is young, it may be beneficial to delay the preservation or try to conceive naturally. A risk of miscarriage and unsuccess ranges up to 45 percent and must be addressed. Cost of these procedures can also pose a burden as a single cycle costs upwards of 6,000 to 10,000 for surgical, medical visits and embryology costs. Additional maintenance and storage fees add up. However for those who suffer from infertility, this is a great option for when they are ready to conceive. Get to learn more about embryo freezing with our consultants in Kuala Lumpur, Malaysia.