Blastocyst transfers
More evidence is suggesting that patients who have undergone multiple
treatment cycles without a successful outcome, having had good quality
embryos may benefit from a blastocyst transfer. Women who are at risk
of multiple pregnancies may also benefit as one blastocyst is normally
transferred.
Blastocyst transfers are normally performed on day 5, rather then day
2 or day 3, following egg collection. The criteria do vary from clinic
to clinic but normally four good quality embryos of 8 cells on day 3 following
egg collection are required.
Hatching Blastocyst
There are some risks involved by delaying transfer. One of those is that
the embryos may not develop to the blastocyst stage. Therefore there may
not be an embryo transfer. Blastocyst transfer is allowing the embryos
to reach a more mature stage of development and some may not have the
potential to do so. They will therefore cease to develop further.
Risks to the children born from blastocyst transfer are still being studied,
as it is still a relatively new procedure. However there is evidence to
suggest that the chances of identical twins are higher as well as the
chances of conceiving a boy.
Freezing of Blastocysts
The freezing of embryos depends on the quality of the embryos. The embryo
quality has to be high for them to survive both the freezing and thawing
process. Blastocysts have reached a stage of maturity where they are ready
to implant therefore clinics offer the freezing of all blastocysts.
The Frozen Embryo Replacement Cycle
Unlike IVF
or ICSI a Frozen Embryo replacement cycle does not require the ovaries
to be stimulated. Instead Oestrogen is administered, normally in tablet
or patch form. This enables the uterine lining to develop for the embryo’s
to be replaced. Vaginal scans will also be performed to check that the
lining is thickening as result of the Oestrogen theraphy. When the lining
has reached approximately 8mm in thickness, the replacement of the embryos
will be scheduled. The unit will then advise the woman when to commence
Progesterone which will help to maintain the uterine lining. Both Oestrogen
and Progesterone are continued until the pregnancy test 14 days after
embryo transfer.
Uterine Lining
It is on the day of the embryo replacement that the embryologists will
thaw the embryos for the transfer. In some cases, not all of the embryos
cryopreserved will thaw successfully.
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