normal egg production
A woman's ovary contains all her eggs. There is a hormonal communication between the
hypothalamus (in the brain), the pituitary and the ovary to enable the
egg (technically we call it the “primary oöcyte”) to be released.
The hormones select the egg that will be used in a particular cycle and
produce fluid around it. This fluid filled ball is called a follicle. A
trigger hormone releases the egg
at a time that allows the lining of the womb (uterus) to be nurtured to
optimise implantation by the time an embryo reaches the womb. Mr Shaw
can explain more of this in consultation.
The development of the oöcyte in the ovary is
driven by Follicle Stimulating Hormone (FSH) released from the pituitary
gland. However the actual release of the oöcyte is dependent on a surge
of Luteinising Hormone (LH), the trigger hormone, from the pituitary in the middle of the
cycle. This hormone is the basis of most ovulation detector kits
Ovulation occurs about 48hours after the LH surge. All of the different
IVF protocols involve accessing the follicle after it has ripened but
before it has released its egg. The Antagonists of the hormone which drives the pituitary, Gonadotrophin
Releasing Hormone (GnRH), cetrorelix and ganirelix,
produce a much more profound inhibition of the pituitary than the GnRH
antagonists. This allows suppression to commence after the stimulation
has commenced. The cycle starts with stimulation.
stimulation
The Stimulation
Phase commences on day 1 of your
period; a scan is booked for day 1-2. If no abnormalities are detected
during the scan commence stimulation with gonadotrophins (until
hCG trigger).
This involves an injection of FSH daily. You can see that the
injections are not as bad as you might think. (http://www.youtube.com/watch?v=tmkyxzMsIxg
). Mr Shaw is very keen that you drink
an abundance of fluids during this phase so there is ample available for
follicular development.
The development of follicles
is monitored by ultrasound of the ovaries and occasional blood tests.
There may be some changes in the dose, depending on your response in
this particular cycle.
Occasionally additional medication is prescribed for the
first 5 days.
The next
scan is booked for day 6-7 of cycle and a scan and oestradiol
blood test are performed every day thereafter.
stimulation with suppression
When the
leading follicle is >14mm, the Antagonist is started in order to
prevent the LH surge. The
cetrorelix or ganirelix is then continued as a daily injection with the
gonadotrohin (FSH) stimulation. (
http://www.youtube.com/watch?v=xG4_0pt3xXk ). The development of follicles
is monitored by daily ultrasound of the ovaries and blood tests.
There may be some changes in the dose, depending on your response in
this particular cycle.
The
side effects
at this phase include redness, pain or irritation from the
injection , breast tenderness, fatigue, ovarian hyper stimulation
syndrome (OHSS), pelvic pain and ovarian cysts. Occasionally the cycle
has to be abandoned if there are too few or too many follicles
developing.
Thirty-five hours before the
planned harvest you should inject the trigger, human Chorionic
Gonadotrophin (hCG).
Surgical
Egg retrieval is precisely scheduled to occur a
specific number of hours after the hCG injection (typically 34 to 37).
Timing is extremely important because the egg retrieval must occur
before natural ovulation occurs. During this procedure, you will be
given a sedative or anaesthesia.
Typically, the mature eggs are collected using an
ultrasound-guided probe and needle. The needle is passed through the
back wall of the vagina and into the ovary. The eggs are then drawn up
into the needle. As with all surgical procedures the
risks include
haemorrhage and infection.
Not every follicle will yield an oöcyte and, when
mixed with sperm, not every oöcyte will be fertilised. Indeed there is
a risk that none will be.
The day of the harvest is the day when the man
has to produce his sample. The quality of that sample will determine the
way in which the sperm is introduced to the oöcyte.
Intra-Cytoplasmic Sperm Injection (ICSI) is available if necessary. In
general the decision can be anticipated by the prior semen analysis. Mr
Shaw will have discussed that in consultation, although the sample on
the harvest day may influence that decision.
Embryos are then replaced on day 2 or more after
the harvest. The timing of this will depend on the number and quality of
your embryos in culture. The embryo transfer (ET) is described by
patients as being somewhat like having a smear
test only with less discomfort.
Two weeks later you perform a pregnancy test and
call the nurse who has being looking after you with the result. We shall arrange a
scan if it is positive and a follow up analysis consultation if negative.
Mr Shaw is very keen to analyse the details of any unsuccessful cycle to
look for clues as to how to improve outcome if a further attempt is
being considered.
It can be seen that the
Antagonist Cycle is more intensive and is more vulnerable to biological
variation as it is less flexible than the Agonist
Cycles. Mr Shaw's choice of protocol is individualised to patient
needs.
