ZIFT (Zygote Intrafallopian Transfer)Similar to in vitro fertilization (IVF), the ZIFT procedure, also known as Tubal Embryo Transfer (TET) involves stimulation of the ovaries to produce eggs, and then egg retrieval. The retrieval of eggs/oocytes can be done by laparoscopic approach (belly-button surgery) or through aspiration of the ovarian follicles under ultrasonographic control through the vagina.
The sperm is collected and processed in the laboratory in an identical way as for in vitro fertilization (IVF). After that it is used to fertilize the eggs. After fertilization, the zygote, a one-cell embrya, is transferred to the fallopian tube via laparoscopy. There were some thought to transferring the zygote into the fallopian tube through a vaginal approach, going through the cervix, into the corner of the uterus and injecting the zygotes into the fallopian tube. These techniques were mostly abandoned because the success was not satisfactory, and because of possible traumatization of the uterine cavity, which is hoped to be healthy and ready to accept and nourish the fertilized egg. Women undergoing the ZIFT or TET procedure, as well as undergoing the GIFT procedure, must have an unblocked and functioning fallopian tube, which are expected to contribute to a considerable degree to successful pregnancy. If the tubes are blocked or suspected not to function appropriately, IVF should be used instead. Trying to do a ZIFT procedure in these situations will increase the risk of ectopic/tubal pregnancy.
The advantage of the ZIFT procedure over the GIFT procedure is that fertilization is verified prior to transfer to the fallopian tubes.
Advantage, disadvantage compared to IVF?
The disadvantage of the ZIFT/TET procedure is that it includes at least one more invasive procedure (laparoscopy), and a procedure to retrieve the oocytes from the ovary, which can be done by another laparoscopy or ultrasonographically controlled vaginal aspiration. Laparoscopic compared to vaginal aspiration of the follicles calls for stronger anesthesia to be used to make the patient feel comfortable.
The main advantage to the ZIFT procedure is believed to be the fact that early development of the embryo after fertilization in the dish happens in a “natural condition” compared to a laboratory development outside of the human/mother’s body.
Testing prior to ZIFT/TET procedure.
Proper consultation and investigation of the fertility problem are necessary in deciding if couples are candidates for the ZIFT procedure. It is extremely helpful to provide information about previous medical care, diagnostic tests and therapy applied in the past. In certain cases, ovaries might not be accessible or visible at the time of laparoscopy and the route to recover eggs from the ovary has to be modified.
- The endocrinological status and regularity of menstrual periods and ovulation should be studied.
- Cultures for bacteria that might destroy the growing embryo should be obtained from the vagina and cervical opening.
- If necessary, inflammation of the uterine cavity will be excluded by endometrial biopsy.
- The immunological condition of the uterus might need to be studied.
- The quality of semen will be investigated: the number of cells per cc, the rate of motility, the quality of motion, normal and abnormal forms, etc.
- The semen will be cultured for the presence of bacteria and studied for the presence of inflammatory cells. Infection of the semen might be lethal to the embryo.
- When indicated, a test of the ability of the sperm to penetrate animal eggs might be ordered (hamster oocyte penetration assay).