Frozen Embryo Replacement Cycle (FER)
This procedure uses previously frozen embryos for
Spare good quality embryos from your IVF treatment that would
otherwise be disposed of are kept and frozen for future use. This
allows a couple to have up to three or four cycles from the same
Frozen embryo replacements can be managed either as a natural
cycle or in a stimulated (controlled) cycle. In a natural cycle no
drugs are given. Ultrasound scans are carried out to monitor the
cycle in order to pinpoint the best time for embryo replacement,
ie, when ovulation has occurred and when the endometrium (lining of
the womb) is suitably thickened and implantation is most
In a stimulated cycle you would need to take medication to
control the timing of your ovulation. Ultrasound scans are used to
monitor the cycle and an injection is given to induce ovulation -
this is done when a leading follicle is considered the right size
and the endometrium is the right thickness.
The timing of the transfer is important. The embryos are thawed
in conjunction with the cycle and are replaced three to five days
after ovulation. Our Embryology team will inform you of how
well your embryos have survived the thawing process and if they are
of good enough quality for your transfer to take place. Sometimes
embryos do not survive the thawing process. If this happens, we
will book a review appointment for you with one of our specialists
to discuss your options going forward.
The embryo transfer is similar to a smear test. It
may cause some minimal discomfort. The culture medium containing
one or two embryos is loaded into a thin catheter with a syringe on
the end. The doctor carefully guides the catheter through the
vagina and cervix, and deposits the embryo(s) into the uterus.
Implantation begins three to four days later.
After the embryo transfer, cyclogest pessaries, which contain
the hormone progesterone, will be prescribed. These are vaginal
pessaries which help to support the lining of the womb. You will be
given specific instructions on how to use these by the nurses.
to read more about Embryo Freezing.