Tubal Embryo Transfer (TET)
Tubal embryo transfer is similar to GIFT and ZIFT in that, as the name says, it is based upon the transfer of embryos.
But, the embryos are at a more advanced stage of development than with these other procedures.
Is this the same as ZIFT?
It may seem as if ZIFT and TET are one and the same procedure but there is a difference between the two. With ZIFT the embryos are transferred back into the woman the day after fertilization. This is known as the ‘1 cell’ or ‘zygote’ stage.
With TET the embryos are transferred back into the woman 2 days after fertilization. This is at the ‘2 cell or 4 cell’ stage.
The procedure is carried out as part of in-vitro fertilization (IVF) at the stage where the embryos are ready to be implanted into the woman’s fallopian tube.
What usually happens during IVF is that eggs and sperm are combined outside of the woman’s body, for fertilization. This fertilization results in the development of an embryo which is then ready to be transferred back into the woman.
Embryo implantation is often carried out via the cervix (vagina) but if there have been problems with this then direct implantation into the fallopian tube may be the answer.
The fallopian tube is where fertilization normally takes place. The resulting embryo travels from the tube towards the uterus where it implants itself on the walls of the uterus. If this is successful then pregnancy occurs.
Note: an embryo undergoes cell division as it develops. It starts off as a single cell before dividing into 2 cells, then 4 cells, 8 cells before becoming a blastocyst. A blastocyst is an embryo which has developed 6 days after fertilization and is ready to be implanted into the uterus.
TET – Assisted Reproductive Technology
Who is suitable for TET?
Women who have at least one healthy fallopian tube and those who aren’t suitable for GIFT or embryo transfer through the vagina (transvaginal procedure).
The TET procedure
Tubal Embryo Transfer (TET)
The woman is given fertility drugs beforehand to stimulate ovulation. These will take the form of hormone injections which help with this stimulation. The effect of these drugs on oestrogen levels will be monitored via blood and ultrasound tests.
She will also be given an injection of human chorionic gonadotropin (HCG) which aids with egg development.
Eggs are extracted from the woman in the same way as IVF, GIFT and other fertility procedures. They are placed in a Petri dish (culture dish used in a laboratory) along with sperm and allowed to fertilize. This usually takes a couple of days.
The next stage is the insertion of the embryos into the fallopian tubes. This is performed as a laparoscopy and involves making a small incision in the abdominal area before inserting a slim tube with a camera attached. This camera gives the specialist a clear view of the fallopian tubes.
TET – embryo
The embryos are inserted into the fallopian tubes (or tube).
These are monitored over the next few days to check for signs of pregnancy. A blood test can confirm or reject a diagnosis of pregnancy.
If pregnancy has been confirmed then hormone injections are given to support this.
Success rates are higher in younger women than those over 35.
The risks of TET are similar to those for IVF, GIFT or ZIFT.
(information from Medic8 – http://www.medic8.com/healthguide/infertility/infertility-treatment/tubal-embryo-transfer.html)
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