Cryopreservation is a technique in which sperm, eggs and embryos are frozen in order to preserve them for future use
Oocyte Cryopreservation Program
Oocyte (Egg) Cryopreservation Program gives women the possibility to store eggs at a younger age for use in the future when they are older. Oocyte freezing can be also used as a medical emergency in the setting of a newly-diagnosed cancer or for personal social reasons.
The technology holds great promise for women of reproductive age. The process involves and begins with ovarian stimulation, then oocyte or egg collection and vitrification procedure, storage in liquid nitrogen at -196° C, and for use at a later date.
Oocyte quality is best when a woman is in her reproductive prime (age 16 to 28). Many eggs are usually still of good quality in the mid-reproductive years (age 29 to 38) and may remain usable (but with diminished chance for producing pregnancy) in the late-reproductive period (age 39 to 44). It is crucial to have eggs frozen when they are of the best quality possible.
Victory IVF Unit has a staff dedicated and skilled to perform egg freezing program to assure patients are properly cared for, counseled and supported. We know this is a big decision for many women and we want to make the process as delightful and satisfactory as possible.
At Victory IVF we use a cryopreservation technique known as “Vitrification”. Vitrification involves ultra rapid freezing of the oocyte from 37 ºC to -196 ºC at a rate of more than 20,000 ºC per minute. High concentrations of cryoprotectants and high cooling rates are necessary to prevent cryoinjury and preserve the oocyte cell. Subsequent to the vitrification, the oocyte is stored in liquid nitrogen until they are needed. The eggs may be kept frozen indefinitely so it is crucial that patients maintain annual contact with the clinic so we know the eggs have not been abandoned.
When the patient decides they are ready to use their eggs, they will be thawed in the laboratory. The thawing process is rapid and is carried on the same day the eggs will be fertilized and must be synchronized with a woman’s cycle. Over 90% of frozen eggs, on average, survive the freeze-thaw procedure.
Thawed eggs are next fertilized in our laboratory using a technique called Intra-Cytoplasmic Sperm Injection (ICSI). A single sperm is injected into the centre of each oocyte. On average, about 60% – 70% of the injected eggs will be expected to fertilize normally.
After fertilization, the oocytes, now called embryos, will be cultured in the laboratory for 2 to 3 days, growing and dividing. Take note that not all fertilized eggs will divide to make nice embryos. Those that do survive and progress are again related to a woman’s age.
Prior to transfer, your doctor will discuss with you the number of embryos recommended for transfer. Your doctor will transfer the fertilized eggs (embryos) into the uterus using a small catheter and are visualized under an abdominal ultrasound.
The following women may benefit from this procedure:
- Patients at risk of premature menopause and ovarian failure
- Oocyte Banking for donation programs
- Fertility Preservation: Women undergoing chemotherapy or radiotherapy to treat cancer
- Women who do not have a male partner or prefer not to use sperm from a partner or donor
- Women that are in a career or are not yet in a stable relationship
- Cases with no sperm available at the time of egg collection
- Patients who prefer to cryopreserve oocytes instead of embryos for religious reasons.
Embryo Cryopreservation (Freezing)
Stimulation of ovaries for IVF or ICSI often leads to excess embryos being created which cannot be transferred in the same treatment cycle. These excess good embryos can be stored by cryopreservation (freezing) for possible transfer at a later date. Selection of the embryos to be frozen is at the discretion of the embryologists as they are able to selection good quality embryos that most likely can survive the rigorous freeze / thaw process. The frozen embryos are stored in liquid nitrogen at 196ºC. At this temperature, there has been no evidence of deterioration over time.
Without the option of embryo cryopreservation (freezing), spare embryos can either be transferred, donated to other couples, used for research or discarded. However, if multiple embryos are transferred, there is an increased risk of a multiple pregnancy because the greater the number of embryos transferred, the greater the risk of multiple pregnancy. Multiple pregnancy carries great risks for the mother and the fetuses.
Embryo cryopreservation (freezing) provides an alternative to discarding these spare embryos. It also provides an alternative to the transfer of multiple embryos.
Patients in an IVF program are usually given hormonal injections to produce more eggs. However these injections may have harmful consequences such as Ovarian Hyperstimulation Syndrome (OHSS). Transferring embryos in a fresh cycle will bring potential life threatening danger to patient with multiple follicles who already has an onset or at a great risk of developing severe OHSS before egg pick-up.
Embryo cryopreservation (freezing) can greatly reduce the risk and severity of OHSS as embryos are frozen in a stimulated cycle and only to be thawed and transferred during a natural menstrual cycle where no medications are given. In fact, the chance of pregnancy may be enhanced with natural menstrual cycle as embryos are transferred into a relatively more natural uterine environment.
Embryo freezing could help to reduce the inconvenience, discomfort and cost of IVF by reducing the need of hormonal injections which is very costly as well as the need to go through egg pick-up procedure again. Usually no medications and operative procedures are required for the transfer of thawed embryos.
Sperm Cryopreservation (Freezing)
Sperm cryopreservation (freezing) involves the whole semen sample to be diluted with an appropriate volume of cryoprotectant. Once cryoprotectant is added, the sample will go through a series of cooling process before it is stored in liquid nitrogen at 196ºC. At this temperature, there has been no evidence of deterioration over time.
There are many situations that may interfere with a man’s future fertility. Some are planned, some are accidental and others are due to complications of illness or their treatment. Some men that can benefit from this procedure involve those who’ve had or have:
- Chemotherapy or radiation therapy
- Occupations with high risk of injury
- Illnesses that may cause erectile dysfunction
- Spinal cord disease or injury
Many men also decide to freeze extra sperm as a safeguard against unforeseen future circumstances.