EGG FREEZING (OOCYTE CRYOPRESERVATION)
Egg Freezing or mature oocyte cryopreservation is a technique used to preserve fertility in women of reproductive age. The treatment cycle is similar to an In Vitro Fertilization (IVF) cycle except the eggs (oocytes) are frozen and stored for later use, and not fertilized with sperm after retrieval.
EGG FREEZING IS RECOMMENDED:
- When a woman is receiving therapy for cancer or other conditions that are toxic or harmful to the ovaries
- When there is a genetic condition associated with premature ovarian failure or positive BRCA mutation where removal of the ovaries is recommended
- When patients have an excess number of eggs and do not want to create a large number of embryos
- To defer child bearing (deferred reproduction)
Evaluation consists of an assessment of ovarian reserve to determine a woman’s ability to respond to fertility medications, and infectious disease testing as required by the Food and Drug Administration (FDA).
Ovarian Reserve Assessment:
Ovarian reserve is a term used to determine the capacity of the ovary to provide eggs capable of fertilization in response to fertility medications. Evaluation of certain hormones (AMH, FSH, and Estradiol), and ultrasound evaluation (AFC) of the ovary are utilized to determine a woman’s ovarian reserve.
AMH (Anti-Mullerian hormone) is a substance produced within the developing follicles in the ovaries and provides insight into the size of the woman’s remaining supply of eggs.
Measurement of FSH (Follicle Stimulating Hormone) and Estradiol levels early in the menstrual cycle help us estimate a woman’s ability to produce multiple eggs in response to fertility medications.
The Antral Follicle Count (AFC) is the number of follicles starting to develop on each ovary early in the menstrual cycle as seen via ultrasound.
Combining the information of the hormone levels (AMH, FSH and Estradiol) and AFC number helps indicate the ovarian reserve. In general, women with high FSH levels, low AMH levels and low Antral Counts are more resistant to ovarian stimulation and produce fewer eggs.
Infectious Disease Testing:
In keeping with federal regulations, individuals are screened for HIV, hepatitis (B and C), West Nile Virus, syphilis, gonorrhea and chlamydia.
STEPS IN AN EGG FREEZING CYCLE:
OVARIAN STIMULATION AND MONITORING
Use of ovarian stimulating medications and careful monitoring are employed to time the egg retrieval to obtain mature eggs.
Before the stimulation begins, birth control pills are used to quiet the ovaries. An ultrasound exam and blood estradiol test confirms this and the woman begins the fertility medications according to a schedule provided by TFC. The medications (Follistim, Gonal-F or Menopur) are injected subcutaneously (SubQ) daily and stimulate multiple follicles to grow. A follicle is a fluid filled sack in which an egg can develop.
Another medication (Ganirelix or Cetrotide) is added to help prevent premature ovulation (release) of the eggs. The eggs are microscopic and can’t be seen directly, therefore we track their development by measuring the size and number of follicles and measuring the level of hormone (estradiol) produced by the follicles.
Together the measurements for follicle sizes and blood tests indicate when the follicles are likely to contain a fully developed egg. A final medication (hCG and/or Lupron) is taken to cause the final maturation of the eggs prior to retrieval.
The egg retrieval is performed using ultrasound to guide a needle through the vaginal wall into the ovaries. The egg retrieval takes approximately 30 minutes to complete and sedation is provided by an anesthesiologist for your comfort and safety. After the retrieval you’ll stay for a recovery period of 45-60 minutes before going home to rest the remainder of the day.
EGG FREEZING OR CRYOPRESERVATION
The retrieved eggs are immediately passed to the embryologist in our IVF laboratory who will count and assess the eggs. Before freezing, the embryologist will remove the layer of cells surrounding the eggs (stripping) and evaluate the eggs for maturity and quality.
All mature eggs are frozen and stored onsite at our Center. The eggs are frozen using a technique called Vitrification, which freezes the egg so quickly ice crystals don’t have time to form within the egg. Since ice crystals can damage the egg, preventing ice crystal formation during freezing improves the egg’s chances for survival during the thawing process. Once frozen, the eggs can be stored indefinitely in liquid nitrogen at -180°C.
AFTER THE EGG RETRIEVAL
The day after the retrieval, you may resume most normal activities-such as driving, work or school. We recommend that you abstain from high-impact exercise until your period starts. Some abdominal bloating and cramping is common for a few days after the retrieval as the ovaries are still enlarged and are recovering from the retrieval procedure. Pain medication is provided as needed and all symptoms resolve within about a week.
There is currently no information regarding whether egg viability or quality declines with time in cryostorage. However studies in the literature report that embryos cryopreserved for up to 10 years have thawed and resulted in a viable pregnancy. While TFC cannot guarantee the eggs will survive the thawing process or create a pregnancy, the thaw rate of vitrified frozen eggs is 90-95% with 75% surviving. Once thawed, the fertilization and implantation rates are similar to that seen with fresh eggs.
When you are ready to start a family, you can attempt to conceive on your own or may use your frozen eggs.