After the embryo is transferred to the uterus during in vitro fertilization (IVF), the embryo “hatches” out of its surrounding shell (called the zona pellucida, Latin for clear zone) in order to implant itself in the lining of the uterus. Assisted hatching (AH) is a procedure in which a hole is made in the shell just prior to embryo transfer to facilitate the hatching of the embryo. Although AH has not been demonstrated definitively to improve overall live birth rates, AH may be used for older women or couples who have failed prior IVF attempts. IVF laboratory conditions can harden the shell artificially, and if the zona pellucida has become too thick, or if the embryo quality is not ideal, AH can be used. There is no clear benefit of AH to improve pregnancy or live birth rates in other groups of IVF patients.
Gamete intrafallopian transfer (GIFT) is similar to in vitro fertilization (IVF) but the egg and sperm are transferred to the fallopian tubes where they are permitted to find each other for fertilization within the body rather than in a laboratory dish. One major difference from IVF is that GIFT requires a surgical procedure, called a laparoscopy, to place the eggs and sperm in the tubes. GIFT is an option for women who have normal fallopian tubes or for couples whose religious convictions prohibit fertilization outside of the body. A limitation of GIFT is that fertilization cannot be confirmed as with IVF, thus GIFT comprises less than 1 percent of all assisted reproduction cases in the U.S.
GIFT treatment may work for any infertility problem except tubal blockage, significant tubal damage, or an anatomic problem with the uterus, such as severe intrauterine adhesions.
Zygote intrafallopian transfer (ZIFT) is another assisted reproductive technique. As with IVF, fertilization occurs in the laboratory, but in a similar technique to GIFT, the fertilized egg is transferred to the fallopian tubes rather than directly to the uterus using a laparoscopy procedure. ZIFT comprises less than 1.5 percent of assisted reproductive cases in the U.S., according to the American Society for Reproductive Medicine.
ZIFT may be the selected form of treatment for any infertility problem except the following: