The purpose of the GnRH-agonist (or
antagonist) is to suppress release of LH (luteinizing hormone)
from the woman's pituitary gland during the ovarian stimulation
process. LH surges would cause premature ovulation (release) of
the eggs.
The purpose of the FSH product is
to stimulate development of multiple follicles (structures that
contain eggs) in the ovaries.
Every
month, as you approach ovulation, a number of follicles begin
to mature (exactly how many varies, and depends on your age).
Usually, the follicle that is mature first is ovulated, and all
the other developing follicles shrink away and are lost in a process
call atresia. When you are on the hormone treatment, most or all
these developing eggs are allowed to continue growing until a
number of them have reached maturity. In this way, we can make
use of eggs that would have otherwise been wasted, without using
up your egg total any faster. Throughout the stimulation period,
you will need to visit either one of our clinics or suburban centers
for ultrasound monitoring and sometimes blood hormone levels.
This will help us know when there are enough follicles that are
mature enough for us to go ahead with the "egg pick-up".
Collecting the eggs
Usually, the egg pick-up is performed
through the wall of the vagina, guided by ultrasound. We prefer
a short acting propofol anesthesia to help you recover immediately
after the procedure. The ovaries are scanned through the vagina,
in the same way that they were during your monitoring. A needle
is placed through the wall of the vagina and into the ovary, where
the follicles are emptied of their fluids and their eggs. You
will feel some pressure on the ovaries during the procedure and
there is often a small amount of bleeding from the wall of the
vagina.
Simultaneously, an embryologist is
present at the time of the procedure, looking through the follicular
fluid, finding the eggs, and scoring them according to their maturity
and quality. All this is done in a special controlled environment
in what is called the culture room.
Collecting
the sperm
To ensure that we have an adequate
quantity of sperm for IVF, 2 days abstinence is required before
giving the semen sample. However, the sperm also need to be quite
fresh, so you should not abstain for more than 4 days beforehand.
(We recommend that you ejaculate on the day of the trigger injection.)
Sperm collection can be done in one of our special, very private
collection rooms . You may do this alone or together with your
wife, whichever you prefer. If you anticipate that you will have
any trouble providing a sample on the day of the egg pick-up procedure,
we can arrange for you to collect ahead of time and have the sperm
frozen. We can also provide special non-sperm-toxic condoms if
you wish to collect at home instead. If you choose this option
though, you do need to get the sample to us as quickly as possible
afterwards. In the laboratory, the sperm will be washed and specially
prepared for IVF.
Fertilization
Your eggs and sperm will be taken
to our embryology lab, which is on the same floor as the day surgery
where you will have had the procedure. Once in the lab, the eggs
are isolated from the fluid and other cells, and prepared for
IVF. The prepared sperm and eggs are combined in a glass dish
filled with a nutritive medium. The eggs are then left in an incubator
overnight. The next day, the eggs are checked for signs of fertilization.
You can tell the difference between a fertilized egg and an unfertilized
egg by two faint spheres visible in an egg after fertilization.
These two spheres (pronuclei) hold
the DNA of the sperm and the egg, and will fuse to form the nucleus
of the embryo (called syngamy). The fertilized eggs will be left
to grow for several days in the laboratory. The embryos grow in
the special mini-incubators that hold only 4 culture dishes, so
that your embryos are not disturbed every time someone else's
embryos are checked on, as they would be in the traditional bigger
incubators. The embryologist will record how many eggs are successfully
developing, and two or three of the embryos will be chosen for
the embryo transfer. Any remaining good quality embryos can be
'frozen' for future use if you wish.
By
the time the embryo is transferred, it consists of at least 2
to 8 cells, surrounded by a soft "shell" (the zona pellucida).
After the transfer, the growing embryo will need to hatch out
of the zona pellucida to implant in the lining of the uterus.
On the day after the egg pick-up procedure, please call us to
find out if the eggs have been fertilized. If at least one embryo
is available for transfer back to your uterus an appointment will
be made for the embryo transfer procedure.
Embryo transfer
The
embryo transfer itself is a very simple procedure, usually taking
just a few minutes, and requiring no anaesthesia or sedation.
The embryos are kept in the laboratory until you are ready for
the procedure. A scientist brings them to the day surgery in the
special controlled-environment chamber, so that they are kept
in optimum conditions right up until they are transferred to your
uterus. The embryos are picked up with special two-part catheter
(a bit like a very thin syringe ). This is carefully guided through
the cervix, and a thin soft tube that will not damage the lining
of the uterus is advanced out to reach the middle of the uterus,
and the embryos are deposited there. The front and back of the
uterus are normally touching, and this holds the embryo in place
- so you can get up straight away.
After
the transfer
To
make sure the lining of your uterus (the endometrium) is ready
for the embryo to implant, you will need to have two injections
of hCG (human chorionic gonadotropin) or better still, daily injections
of progesterone in oil (Inj Gestone / Puregest / Susten). This
helps the endometrium swell up and envelop the embryo so it has
the best chance to implant. If your hormone levels are high, we
many recommend progesterone pessaries instead of further Profasi
or Pregnyl.
From this point, it is a matter of
waiting to see if an embryo implants successfully and begins to
develop. A pregnancy test can be performed about 16 days after
the egg pick-up and the nurse co-ordinators will have the results
for you.
Blastocyst Transfer
A
blastocyst transfer is the transfer of an embryo from the laboratory
to the uterus at Day 5 of development, instead of Day 3. it is
one way of selecting the embryo or embryos most likely to survive
and implant, giving a better chance of pregnancy. To appreciate
the difference two extra days can make to an embryo, first you
need to understand a little about early embryo development.
The
first week…
After
the sperm enters the ovum, the sperm head enlarges to form the
male pronucleus. Within 24 hours, two small spheres, called the
pronuclei, can be seen in the cytoplasm of the egg. These contain
the genetic material from the mother and the father. When the
two pronuclei fuse, joining the DNA from both parents together,
fertilization is complete. As the pre-embryo grows, it undergoes
cleavage, where the cell divides into smaller cells call blastomeres.
After 2 days, the embryo will consist of 4-8 blastomeres. At this
poing it is impossible to tell which embryos are most likely to
survive and develop normally. After about 3 days, when the embryo
consists of 12-16 blastomeres, the cells begin to compact, forming
a morula. This is the stage at which the embryo would normally
enter the uterus, where it floats for a day or two before attaching
to the lining of the uterus.
During those two days, huge changes
in the embryo's appearance can be seen, as the cells begin to
differentiate into those that will become the fetus, and those
forming the amniotic sac and placenta. These changes are characterized
by the formation of a cavity in the morula, to create a blastocyst.
After 4 or 5 days the embryo "hatches"
out of the outer shell of the egg, the zona pellucida, and the
blastocyst is able to attach to the endometrium. By Day 7, the
embryo has completely implanted in the lining of the uterus.
Why
have a blastocyst transfer?
By
watching the embryo develop to the blastocyst stage, the embryologists
can have a better idea of which embryos are most likely to be
healthy and continue to develop. One of the factors that decides
an embryo's fate is whether or not it has enough energy for the
first week of development, hatching and implantation. Of course,
there are still many stages of development that the embryo must
pass through to create a successful pregnancy, but choosing the
healthiest 5-day-old embryos and transferring them just before
they would normally implant has given us the best success rates
yet. Ultimately, our goal is to have such high success rates that
only one blastocyst will need to be transferred in each cycle
for a good chance at pregnancy.
We often recommend blastocyst transfers
for couples who have had a number of unsuccessful attempts at
routine IVF. Whether you have your embryos transferred at Day
2-3 or Day 5 is your decision. Some patients prefer to have the
embryos put back earlier rather than risk there not being any
still developing on Day 5, while others would prefer not to have
the transfer if the embryos do not survive to Day 5.
Freezing
Blastocysts
Normally
"spare" embryos are frozen at the 4-8 cell stage, and provide
good results when transferred after thawing. We are now able to
successfully freeze and thaw blastocysts. The limited number of
cases so far mean that we don't yet have reliable data on success
rates for transfer after blastocyst freezing.
What
does a blastocyst transfer mean for you?
Essentially,
a blastocyst transfer means that your transfer will be one or
two days later than it would have been otherwise. There are no
different medications or extra procedures, although it does incur
an additional charge. Having a blastocyst transfer can also mean
that by Day 5 you might have fewer embryos than at Day 3, but
that those embryos lost along the way would not have created a
pregnancy anyway.
How is assisted hatching performed?
