Embryo and Sperm Freezing (Cryopreservation)
Evidence shows that prolonged storage of
embryos or sperm has no detrimental effect on their survival rates, or their
ability to implant. Children born as a result of frozen embryo transfer or the
use of frozen sperm do not have a higher rate of birth defects nor have any long
term effects been identified. To date, the technology to freeze unfertilized
human eggs (oocytes) is performed on an experimental basis and is not routinely
available. Embryos and sperm are frozen and stored in liquid nitrogen at the
temperature of -196oC (-321oF).
Embryo Freezing
The number of embryos transferred to a
patient’s uterus after IVF depends upon several factors, including the number
that are available, the quality of the embryos, the woman’s age and the
patient’s wishes. The more embryos transferred, the greater the chance for
pregnancy to result. The more embryos transferred, however, the greater the
chance for a multiple pregnancy. While twins are associated with a slightly
higher chance of complications than singleton pregnancies, high-order multiple
pregnancies (more than two fetuses) are associated with a much higher chance of
problems. The most serious of these is premature delivery.
For these reasons, some patients may decide
to limit the number of healthy-appearing embryos transferred to the uterus when
many such embryos are available. This is an issue that will be thoroughly
discussed with you before, and especially if, you find yourself in the fortunate
position of having excess, good-quality embryos. Good quality
embryos that are
not transferred can be frozen for transfer at a later date. F.I.R.S.T. has storage
facilities on the premises and will store the embryos without charge for one
year.
The technique of embryo freezing has been
used in IVF for many years and has the great advantage of providing
embryos for
future use without the need for another egg collection. There are no extra
charges at F.I.R.S.T. for embryo freezing. There are charges, though significantly
less than for a full IVF cycle, for the transfer of frozen
embryos. Frozen
embryo transfer may be carried out in natural cycles or simulated cycles. In a
simulated cycle, drugs are used to mimic a perfect menstrual cycle and the
embryos are planned to be transferred on a specific date. The merits of the
different preparation methods will be discussed with individual patients, and a
decision as to which method is best will be made on a case-by-case basis.
Keep in mind that poor quality embryos do
not freeze very well and some good quality embryos do not survive the
freeze-thaw process well either. (Approximately 75% of embryos survive thawing.)
Even if embryos thaw well, the implantation rates for frozen
embryos are not as
high as for fresh embryos. These facts will be taken into consideration when
deciding how many fresh embryos to transfer or whether or not to freeze
embryos.
Sperm Freezing
Sperm freezing and storage is available at F.I.R.S.T. Some patients find this service particularly convenient if the male
partner has difficulty producing a specimen on demand or has a schedule that
will not enable him to be readily available to give a semen specimen when
needed. The fee to freeze a specimen is $150.00. Often, one ejaculate may be
divided and used for more than one treatment cycle. We will store your specimen
for one year free of charge.
Men with malignancies, about to start
chemotherapy or radiation treatment (which often render men sterile), may choose
to freeze sperm before treatment. Cryopreserving even suboptimal semen samples
can now be used with ICSI to establish previously unobtainable pregnancies.
Sperm freezing is also recommended for men who have recently undergone vasectomy
reversal. If sperm appears in the ejaculate after a successful procedure, it is
prudent to freeze several specimens for future use in the event that the
reattached sperm ducts scar and become blocked over time.
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