 ZIFT (Zygote Intrafallopian
Transfer) |
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| Similar to 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. 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 was 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.
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Advantages, disadvantages compared to IVF? |
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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.
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For your convenience, please visit our Glossary
of Terms and Definitions,
our more comprehensive Glossary
and our Tyler Medical Clinic
Infertility Library
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Testing Prior to
the ZIFT/TET Procedure
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| 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.
Useful Information
Female:
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The endocrinological status and regularity of menstrual periods
and ovulation should be studied.
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Cultures for bacteria that might destroy the growing embryo
should be obtained from the vagina and cervical opening.
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If necessary, inflammation of the uterine cavity will be
excluded by endometrial biopsy.
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The immunoligical condition of the uterus might need to be
studied.
Male:
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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).
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