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| Ensuring The Future With Oocyte Cryopreservation |
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| Written by Webmaster | |
| Monday, 02 February 2009 | |
By Dave Stringham Egg freezing is a breakthrough technology that allows women to freeze and store their eggs until a pregnancy is desired, at which time the eggs are thawed, fertilized and transferred to the uterus as embryos.
Who May Benefit? Many women today are feeling the pressure of having to choose between a career and a family. Some are returning to school or pursuing advanced degrees and don't know when or if they will have children. For many, it may simply be an issue of not having found the right person yet. For all of these women, egg freezing is revolutionary not just in its technology, but in the freedom it can offer in allowing them to postpone childbearing. Over 50,000 reproductive-aged women are diagnosed with cancer each year in the United States. Surgery, chemotherapy and radiation treatments typically lead to infertility by destroying the eggs. While options vary depending on age, type of cancer and cancer-treatment plan, egg freezing can provide these women the opportunity to preserve their fertility. Finally, egg freezing can be useful for individuals with religious or moral objections to storing frozen embryos. Frequently, in routine IVF, any excess embryos that remain are frozen for future use. However, if they are not to be used, their disposal can create a difficult ethical issue. The ability to freeze unfertilized eggs offers a positive solution for many people. How Egg Freezing Works Unlike sperm and embryo cryopreservation, which have become routine processes in assisted reproductive technology, success with freezing eggs has historically been difficult to achieve. This is because the egg is the largest cell in the human body and contains a considerable amount of water. When eggs are frozen, ice crystals form that can destroy the cell. To prevent this, the egg must be dehydrated prior to freezing. The water is then replaced by a special "antifreeze" that inhibits the formation of ice crystals. Because the eggshell hardens when frozen, sperm must be injected with a needle in order to fertilize the egg. This is known as ICSI (intracytoplasmic sperm injection) and is a standard technique also used in IVF. Eggs can be frozen using either the much-studied slow-freeze method, or a newer flash-freezing process known as vitrification. Initial studies of vitrification were performed using methods that expose eggs directly to liquid nitrogen, which can harbor viruses. However, there is no risk of viral contamination, as a vitrification system uses closed containers. An FDA-approved clinical trial of this closed vitrification system demonstrated pregnancy rates over 50% per transfer. It takes approximately four to six weeks to complete the egg freezing cycle, which follows the same protocol as IVF: Two to four weeks of self-administered hormone injections along with birth control pills to temporarily turn off natural hormones. This is followed by ten to fourteen days of hormone injections to stimulate the ovaries and ripen multiple eggs. Once the eggs have matured, they are removed through the vagina using an ultrasound-guided needle. This procedure is done under intravenous sedation and is not painful. Immediately following retrieval, the eggs are frozen. When embryo transfer is desired, the eggs are thawed, injected with a single sperm to achieve fertilization, and transferred to the uterus as embryos. Storage Our data indicate that for every ten eggs frozen, seven should be viable after thawing. Of those, we expect to fertilize four to five. And finally, three to four embryos are transferred to the uterus. We therefore recommend that at least ten eggs be stored for each pregnancy attempt. For women under thirty-eight years of age, we normally harvest ten to twenty eggs per cycle. Based on our success with embryo freezing, we believe that long-term storage of frozen eggs is possible. Due to the age cutoffs in egg freezing studies, we do not have any reports of pregnancies in women over thirty-eight. At this time, we do not know if eggs from women over thirty-eight will respond similarly to those from women thirty-eight and younger. However, we do routinely see pregnancies achieved in women up to age forty-three when using fresh or frozen embryos. Safety To date, approximately 600 babies have been born worldwide from frozen eggs. Among these births, the rate of birth defects and chromosomal defects has been no higher than that which we see in the general population. Additionally, genetic screening of embryos is available. Dave Stringham, the President of LookingYourBest.com writes about plastic surgery in Santa Monica, California and medical procedures such as egg freezing and fertility, and surgery procedures such as ear pinning, arm lift, liposuction, and nasal surgery. http://www.santamonicafertility.com Tag it:                  |
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| Last Updated ( Monday, 02 February 2009 ) |
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