Tubal Embryo Transfer (TET): The transfer of embryos to the fallopian tubes for purposes of achieving a pregnancy. Embryos may be transferred at the fertilized oocyte (zygote) stage in a ZIFT (Zygote Intrafallopian Transfer) procedure or 24 hours later at the 2- to 6- cell stage in a TET procedure.
TET's are mainly used for patients who have a difficult transcervical intrauterine transfer and/or patients who have failed previous IVF and FET cycles due to poor embryo quality. The theoretical advantage of a ZIFT or TET procedure over GIFT or IVF is that fertilization is known to occur, however, embryo development can take place in the natural tubal environment with no possibility of trauma to the endometrial lining caused by a difficult embryo transfer. TET has the advantage over ZIFT of allowing selection of the best quality embryos while giving patients additional time for recovery from the egg aspiration. The majority of TET procedures are performed on male-factor patients with difficult transcervical intrauterine transfers.
This definition is from fertile.com