Gamete Intra-Fallopian Tube Transfer
Although gamete intra-Fallopian tube transfer (GIFT) is similar to IVF in that ova and sperm are mixed in an artificial environment, the main difference is that with GIFT both the ova and sperm are placed in the Fallopian tube prior to fertilization. Fertilization is allowed to occur naturally in the Fallopian tube, rather than in an artificial environment; fertility drugs and sperm washing are also used. This process has resulted in much higher implantation rates.
Zygote Intra-Fallopian Tube Transfer
Similar to both IVF and GIFT, the zygote intra-Fallopian tube transfer (ZIFT) procedure allows ova and sperm to meet outside the body, where fertilization occurs. Directly following fertilization, the embryo is placed in the woman’s Fallopian tube, allowing it to travel to the uterus and implant naturally. Fertility drugs and sperm washing are also used. This procedure has been found to yield higher implantation rates than IVF but not higher than GIFT.
Sometimes ova are resistant to fertilization due to problems with the enzyme in the head of the sperm, which is supposed to break down the hard outer covering of the ovum and allow fertilization. Zonal dissection involves drilling a microscopic hole in the ovum with a very small needle, making a small slit in the side of the jellylike coating, or using a chemical to dissolve the outer shell. Unfortunately, one drawback to this procedure is that several sperm may enter the ovum and cause developmental problems in the resulting embryo.