Assisted reproductive techniques of a series of treatments aimed at artificially helping egg fertilisation by the sperm and later embryo implantation to occur, helping thus on the way towards the desired pregnancy. In what follows we shall explain the Zygote Intrafallopian Transfer (ZIFT) technique.
There are a series of techniques aimed at solving infertility problems, ranging from less complex procedures, such as artificial insemination, to more complex procedures, such as Intracytoplasmic Sperm Injection or ICSI.
One of the lesser-used assisted reproductive techniques –because it is a highly invasive method– is Zygote Intrafallopian Transfer or ZIFT, which is the result of combining in vitro fertilisation and Gamete Intrafallopian Transfer (GIFT).
In order to be able to carry on this technique, the patient must not have any tubal obstruction. In addition, at least one of the tubes has to be permeable to ensure implantation –if not, implantation would not occur. Women suffering from some kind of uterine-related problem or with previous ectopic pregnancy history are not recommended to undergo this technique.
Regarding men, semen quality has to be adequate enough to ensure that egg fertilisation occurs. In cases of men with low semen quality, ZIFT is usually combined with intracytoplasmic sperm injection.
To perform a zygote intrafallopian transfer, controlled ovarian hyperstimulation –as in the case of in vitro fertilisation– is required in order to obtain a larger number of oocytes. When follicles have achieved an adequate size, follicular puncture is performed under sedation. Once the oocytes are removed, they are cultured together with the partner’ or donor’ sperm. After a few hours, fertilisation is checked. Then, the fertilised eggs or zygotes are transferred into the patient’s Fallopian tubes.
Zygote transfer is conducted via laparoscopic surgery. It consists of a small incision under the navel, through which a tube is inserted into the Fallopian tubes. One up to four zygotes will be injected into the tubes and they will travel into the uterus on their own, where embryo implantation may occur.
Advantages and disadvantages
Zygote intrafallopian transfer has several advantages, especially if compared to gamete intrafallopian transfer or GIFT. The main advantage is that the pregnancy rate increases, since the gametes are not inserted separately but only those which have been previously fertilised. Those who support or use this technique stress that this procedure is similar to natural fertilisation, since the embryo spends a shorter period of time outside its natural environment and, thus, its quality improves.
However, ZIFT has also many negative points. One of its main disadvantages is that ectopic pregnancy is more likely to happen. Moreover, an invasive surgery is required, which implies greater levels of difficulty and potential risks. It is also worth to mention that, since more than one zygote can be inserted, the rates of multiple births, miscarriage, and other problems derived from pregnancy are higher if compared to other techniques.
Chances for pregnancy in patients undergoing ZIFT are due to rise up to 36%. Of these, approximately 29% come to the point of delivery, since there is a certain percentage of miscarriage.
There are also many cases of triplet pregnancy or more than three embryonic sacs, since up to 4 zygotes can be inserted with this technique.