Fertility Preservation for Women (Egg & Embryo Freezing)
The Center for Human Reproduction’s Dr. Vitaly A Kushnir discusses embryo freezing, which requires a woman to undergo an IVF cycle, as a method of fertility preservation for women at CHR.
There are a number of different established and emerging techniques for fertility preservation in women. The one that is most established is cryopreservation of the embryos. This has been done for many years and we have great experience with this as do other centers around the world. Embryo freezing requires generally that the woman undergoes an IVF cycle. The eggs that are collected in the IVF cycle are then fertilized with either her partner’s sperm or donor’s sperm, and the resulting fertilized eggs, which are now called embryos, are frozen to be used at a later date. The number of embryos that are needed depends on the woman’s age. In general, the older the patient, the more embryos she should freeze to ensure that she has a good chance of achieving pregnancy with those embryos. In the recent couple of years, egg freezing has become more and more widely utilized and we’ve gained a lot of experience with this as well. It’s now considered no longer to be experimental in the setting of cancer or where a woman is facing therapy medical treatments which will impair her ovarian funcation. It is still considered experimental for social fertility preservation, although it is being used for that widely including in our center. Egg freezing is somewhat different from embryo freezing because it’s a great option for women who don’t have a spouse and who are not willing to fertilize their eggs with the sperm of a sperm donor, but it has it’s limitations as well. For example, eggs are much more difficult to freeze than embryos because an egg is a big cell, whereas an embryo consists of many small cells and it’s very technically difficult to freeze a big cell that’s an egg compared to the embryo. So, in general, women who are looking to do egg freezing, whether it’s for medical reasons or for social reasons, we’ll need to freeze more eggs than women that are freezing embryos. Another great option for women who’ve newly been diagnosed with cancer or another serious medical problem who need therapy very quickly for this, is ovarian tissue freezing and CHR has recently started offering this procedure. This is still considered experimental, but there have been numerous pregnancies now documented after that tissue has been retransplanted into patients who have undergone chemotherapy, then subsequently went into an early menopause. The tissue was then retransplanted back into their ovary and they regain, 90% of patients in most studies, have regained ovarian function and resumed their monthly cycles. And there have been about 40 or 50 pregnancies now documented around the world from following this procedure, so we are excited to offer ovarian tissue cryopreservation. This is actually a great option for many women who don’t have necessarily the time to freeze eggs before starting chemotherapy or radiation therapy because ovarian tissue freezing can be done literally the next day after I meet the patient. We go to the operating room, take out of a portion of the ovary, and the patient can start treatment right away. The other group of patients for whom ovarian tissue freezing makes a lot of sense is for kids because really, egg and embryo freezing is not an option for them. We’re not going to be able to retrieve eggs from these patients. So, for a young girl who hasn’t reached puberty yet, this is really the only option at the moment to preserve her fertility before she undergoes therapy that will potentially destroy her ovarian function. So, again this is a great option for a variety of different settings. Medical management of fertility preservation has also been gaining a lot of attention recently. This is mostly in women who are already undergoing chemotherapy or radiation. There are now medicines that can be given in parallel with our primary treatment which can sort of suppress the ovaries and help preserve some of the ovarian reserve and egg supply and there have been a number of studies showing that these kind of medications can be effective in helping women to preserve their fertility while they are undergoing these treatments for cancer. The last and probably most infrequently used fertility preservation approach is for women with gynecological cancers, and there are a number of different of surgical mentalities that are used here, whether it’s transposition of their ovaries out of their radiation field, or a cervical trachelectomy where only the cervix is removed in cases of cervical cancer but the uterus and ovaries are spared and also some medical management that are used specifically for women with gynecological cancers which include ovarian cancer and endometrial and uterine cancer as well as other urogenital cancers.