Who needs cryopreservation and storage of gametes (eggs/sperm)

For egg cryopreservation and storage

1. Preservation for single patients who may lose her ovarian function (e.g. cancer patients before resection surgery, chemotherapy or radiation therapy)
2. As egg quality decreases dramatically after 35, egg preservation for future use can help to conserve the reproductive ability of women aged ≥30 years old who are still single or not yet ready to conceive
3. Women with the tendency or family history of premature menopause
4. Planning to delay childbirth for study or career development, etc.
5. Social egg freezing
6. No available sperm for insemination after egg retrieval in IVF treatment
7. Egg donation

For sperm preservation

1. Diseases that require treatment that can compromise sperm production and function (such as chemotherapy, radiation therapy or resection surgery for cancer)
2. For backup in IVF treatment cycle, especially for husband with very low sperm count or ejaculation disorder or require surgical sperm extraction to retrieve the sperm (e.g. TESA, MESA)
3. Planning to delay plan for having children because of study or career development, etc.
4. Sperm donation

1. Egg quality and successful pregnancy rate post thaw is closely related to age of female at egg retrieval (the best age range is between 20-35 years)
2. Treatment procedure of egg preservation is very similar to that of IVF, using medicine to stimulate follicular development and mature eggs are retrieved. The major difference is that eggs are not fertilized but frozen and stored in liquid nitrogen for future use
3. By Hong Kong Law, maximum period of gamete storage is up to 10 years except for special cases like cancer patients, it can be 10 years or until the age of 55
4. A patient can give written notice to the centre to have his/her cryopreserved gametes to be transferred to another qualified IVF centre at home or abroad. This process needs consents and proper co-ordinations in advance by qualified personnel
5. Cryopreserved eggs can be thawed for future use only after marriage, but there is no guarantee of a successful pregnancy, as this depends on many factors such as her age when the eggs were frozen and the total number of eggs frozen. Clinical pregnant rate per egg: age < 30 years, 4.5% - 12%; < 38 years, 2% - 12% (ASRM–SART practice guideline estimate)
6. It normally requires at least 8-10 frozen eggs for the chance of one successful pregnancy for patients ≤ 38 years old
7. Generally speaking, when eggs are frozen at a younger age, the egg quality is better but the chance of using them is lower whereas the quality of frozen eggs from older women is less favorable but the chance of using them later is higher