Assisted Reproductive Technologies

Specific Procedures

In Vitro Fertilization (IVF). About 71% of ART procedures use in vitro fertilization (IVF) with the woman’s own eggs. An in vitro procedure is one that is performed in the laboratory. With in vitro fertilization (IVF), the partners’ sperm and egg are placed together in a laboratory dish, where, it is hoped, fertilization will occur. It is the most common assisted reproductive treatment. The best candidates for IVF are women with damaged fallopian tubes, and some experts believe it is a better option than attempting surgical repair. It is also used when infertility is unexplained and when the male partner has the infertility problem. Most IVF programmers do not take women over 42. The physician induces super ovulation using fertility drugs so that several eggs can be harvested from the ovary before they have been released from the follicles. (Some women prefer to try a natural cycle, which produces only one egg.) It does not appear that using higher doses of fertility drugs for subsequent cycles is beneficial in women who have a poor response the first time. To harvest eggs, the physician uses either laparoscopy, inserting the instruments through an incision at the navel, or a probe inserted into the vagina and guided by ultrasound. The physician uses a needle to drain the liquid from the follicles and retrieves several eggs. The process requires light anesthesia and is performed on an outpatient basis. The eggs and sperm are combined in a petri dish, and 48 hours later, when the eggs are fertilized, they are re implanted into the woman’s uterus as embryos. Most centers now implant three to four embryos at a time, and the remainder can be frozen for future use. Experts are devising a formula to reduce the risk for multiple births based on the woman’s age and the number and quality of embryos that should be transferred back into the uterus.
Gamete/Zygote Intra fallopian Transfer. Gamete intra fallopian transfer (GIFT) and zygote intra fallopian transfer (ZIFT) are adaptations of IVF. A woman must have at least one functioning fallopian tube, GIFT and ZIFT are used in unexplained infertility, severe endometriosis, and in male infertility. In GIFT, the eggs are harvested as in IVF but not fertilized. They are mixed with the sperm and immediately injected back into the fallopian tube through a long, thin catheter. The sperm and egg are placed exactly where they would be in natural fertilization. The success rate is slightly higher for GIFT than for IVF. The ZIFT procedure fertilizes the eggs in the laboratory, as in IVF, but then implants them in the fallopian tubes, as in GIFT. The advantage to this procedure over GIFT is that the physician and couple are assured that fertilization has taken place and the eggs can be examined for defects.

Intracytoplasmic Sperm Injection

Intracytoplasmic sperm injection (ICSI) is a highly sophisticated technique for injecting one single sperm into an egg using microscopic and micromanipulation instruments. It is used for couples who have failed IVF or when the man has severe infertility problems and now constitutes about 30% of ART cycles that use the woman’s own eggs. It is the most effective procedure when male infertility is the problem.

Other Experimental ART Procedures

New techniques involving micromanipulation of sperm are being developed for the one–third of infertile men who have severely low sperm counts, a high percentage of abnormal sperm, tubular obstruction, or no vas deferens. One investigative approach involves culturing poor sperm with the egg in very small micro chambers, thereby increasing the odds that the sperm will find the egg. A technique called sub zonal sperm microinjection injects one to 15 sperm under the zona (the tough outer shell of the egg). Zona dissection involves puncturing the zona and then incubating the egg in a droplet of 10,000 to 50,000 highly motile sperm. There is concern that puncturing the egg may damage it. Also, since a small number of sperm are randomly selected and not competing in a hostile environment, a weak sperm will have as good a chance as the strongest. This increases the risk for genetic defects in the infant. An experimental technique called FASIAR (follicle aspiration, sperm injection, and assisted follicular rupture) may prove to be a significantly less expensive treatment and also reduce the risk of multiple births. After ovulation induction, the physician punctures the follicle and retrieves the eggs and fluid in a syringe that also contains sperm. The mixture is then re injected near the ruptured follicle. The procedure can be done in the physician’s office. Procedures called round spermatic nuclear injection (ROSNI) and elongated spermatic (ELSI) use immature sperm aspirated from the testes and injected into the egg using ICSI. The sperm can either be fresh or frozen. The procedures are controversial. However some countries are prohibiting this approach. Some centers are developing IVF techniques that allow a longer time for the embryo to develop in the laboratory (five days instead of two to three). This enables the embryo to reach the blast cyst stage, which is the natural embryonic stage for implantation in the uterus.