Different techniques connected to classical IVF have been developed
:
1. Cryopreservation is a procedure of freezing and storing supernumerary
embryos at -196°C in liquid nitrogen. Since no more than
3 fresh
embryos are ever replaced into the uterus at each trial, it is
possible to freeze exceeding embryos if they are of good quality.
In case of failure of a trial to produce a pregnancy or if another
pregnancy is planned later on, the stored embryos can be used
after thawing by replacing them into the mother's uterus during
a natural
cycle, without having to go through another oocyte pick-up.
This method has already produced numerous births of normal babies.
This explains why you were asked to fill out a questionnaire
about the fate of eventual spare embryos.
2.
GIFT (Gamete Intrafallopian Transfer) : this method consists In
retrie- ving oocytes and replacing them by laparoscopy
into the tubes,
together with a suspension of capacitated sperm. Fertilization
occurs, normally, in the tube and the eggs follow the natural path
to the uterine cavity where they
can implant.
3. ZIFT(Zygote Intrafallopian Transfer) : in this approach
oocytes are retrieved as usual through vaginal echographically-guided
puncture. They are then inseminated in vitro and replaced
into the tubes by laparoscopy
on the next day.
The GIFT and ZIFT methods both require that at least
one tube be intact and healthy and requires laparoscopy.
Nowadays,
they
are rarely applied,
in very specific cases.
4.
Oocyte donation (Fig.
10) is the only hope for certain patients
suffering from premature
ovarian failure (i.e. occurring between 20-40 years of age) to
obtain
a pregnancy. This procedure is also applicable to infertility
due to surgical removal of the ovaries. The oocytes
are given by normal women
who spontaneously offer their help to these patients.
In this case, oocyte retrieval is carried out from the donor's
ovaries
as in a usual
IVF trial, after ovarian stimulation.
In practice, the method implies the following steps
:
In the recipient :
Insemination
of the donated oocytes is carried out with a sperm preparation
of the recipient's
partner. Transfer of embryos
to the recipient's uterus is carried out as usual.
This method has already allowed the birth of numerous
children.
5.
Embryo donation (Fig. 11) is aimed at couples who cannot
be treated
through oocyte
donation
because both
partners
are infertile.
Here again,
an artificial cycle is
induced in the recipient
woman in order
to allow
the embryos to implant.
In case of donation of
fresh embryos,
the donor
and the recipient's
cycles must
be synchronized
before embryo transfer.
If
frozen embryos are to be replaced thawing
will have to take place
at
an appropriate time
of the recipient's
artificial
cycle. In both cases
embryo transfer is
carried out as in standard
IVF.
Donated embryos are
provided by ordinary
IVF couples
who accept to give
their spare embryos
in order
to help other
sterile
couples.
Oocyte and embryo donation
can only be achieved
thanks to the
generosity
and
solidarity between
couples.
6.
Surrogate motherhood (i.e. uterus loaning)
is currently
the only
possibility for women,
who have
no functional
uterus, to
have a child
to whom they are
genetically related.
