Gamete and zygote intrafallopian transfer (GIFT and ZIFT) for infertility
Treatment Overview
Some infertile couples are affected by conditions that prevent the sperm and egg from travelling through a fallopian tube, where fertilization and the first stage of cell division take place. The following are assisted reproductive technology (ART) procedures used to improve the chances of conception in the fallopian tubes. The first step of each of these treatment cycles is superovulation, the stimulation of multiple egg production with a series of hormone injections.
Gamete intrafallopian transfer (GIFT) uses multiple eggs collected from the ovaries, which are placed into a thin flexible tube (catheter) along with the sperm to be used. The gametes (both eggs and sperm) are then injected into the fallopian tubes using a surgical procedure under general anesthesia called laparoscopy.
Zygote intrafallopian transfer (ZIFT) combines in vitro fertilization (IVF) and GIFT. Eggs are stimulated and collected using IVF methods, then mixed with sperm in the laboratory. Fertilized eggs (zygotes) are then laparoscopically returned to the fallopian tubes where they will be carried into the uterus. The goal is for the zygote to implant in the uterus and develop into a fetus.
Pronuclear stage tubal transfer (PROST), similar to ZIFT, uses in vitro fertilization but transfers the fertilized egg to the fallopian tube before cell division occurs.
Because of the higher costs and risks related to laparoscopy, and the lesser amount of diagnostic information about embryo development compared with IVF, these procedures are used only rarely.
See an illustration of the female reproductive system
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The treatment process
- Ovulation and egg retrieval. To prepare for an assisted reproductive procedure using your own eggs, you must undergo daily injections and close monitoring for 2 weeks before egg retrieval. At home, you or your partner injects you with gonadotropin or follicle-stimulating hormone (FSH) to stimulate your ovaries to produce multiple eggs (superovulation). After the first week, your doctor checks your blood estrogen levels and uses ultrasound to see whether eggs are maturing in the follicles. During the second week, your dosage may change based on blood tests and other test results. If follicles fully develop, you are given a human chorionic gonadotropin (hCG) injection to stimulate the follicles to mature. The mature eggs are collected 34 to 35 hours later by laparoscopy or needle aspiration guided by ultrasound through the abdomen to the ovaries.
- Sperm collection. Sperm are collected by means of masturbation or by taking sperm from the scrotum (when there is a blockage that prevents sperm from being ejaculated or when there is a problem with sperm development).
- For GIFT, the sperm are then placed in a tube (catheter) with the eggs. The catheter is inserted through a small abdominal incision and into a fallopian tube. The eggs and sperm are then injected into the fallopian tube. Usually, two eggs are placed in each fallopian tube.
- For ZIFT, in vitro fertilization is performed. The resulting fertilized eggs (zygotes) are injected into the fallopian tubes in the same way that GIFT is done. The zygotes then travel into the uterus, where it is hoped that they will implant and develop.
What To Expect After Treatment
Overall, assisted reproductive technology (ART)–related injections, monitoring, and procedures are emotionally and physically demanding of the female partner. Superovulation with hormones requires regular blood tests, daily injections (some of which are quite painful), and frequent monitoring by your doctor.
You can expect to return to daily activities after a routine laparoscopic procedure in less than a week.
Why It Is Done
GIFT or ZIFT is most appropriate when:
- A couple has religious objections to fertilization taking place outside the body.
- A couple with unexplained infertility only has insurance benefits for GIFT.
For GIFT or ZIFT, a woman must have at least one functional fallopian tube.
How Well It Works
Note: ZIFT and GIFT are used rarely enough that specific success rates aren't nationally available. However, what is known about assisted reproductive technology (ART) includes the use of ZIFT and GIFT:
A couple's odds of having a child using ART vary with the woman's age, the cause of the couple's infertility, and pregnancy history. Women aged 35 to 40 and older have lower success rates due to aging of the egg supply. Older women often are advised to use donor eggs to achieve a viable pregnancy.
- Pregnancy history. A woman who has already had a live birth is more likely to have a successful ART procedure than a woman who hasn't given birth before. This "previous birth advantage" gradually narrows as women age.1
- Own eggs versus donor eggs. Birth rates are affected by whether ART procedures use a woman's own eggs or donor eggs. Per embryo transfer:1
- Using her own eggs, a woman's chances of having a live birth decline from over 40% in her late 20s, to 30% at about age 38, and to 10% by about age 43.
- Live birth rates are the same among younger and older women using donor eggs. Women in their late 20s through mid 40s average about a 50% birth rate using fresh (not frozen) embryos.
Canadian Online IVF Resource Network lists fertility treatment centres in each province. See the listing of Canadian infertility clinics at http://www.ivf.ca. Individual clinics may list recent information about assisted reproductive technology success rates on their Web sites.
Risks
Risks resulting from laparoscopy (which may be used to collect eggs) include pelvic infection, puncture of internal organs, and side effects from general anesthesia.
Assisted reproductive technologies—including GIFT and ZIFT—increase the risk of multiple births.1 A multiple pregnancy is high-risk for both mother and fetuses.
ZIFT success versus the risk of multiple pregnancy
In order for a woman over age 35 to maximize her chances of conceiving with her own eggs and carrying a healthy pregnancy, she must have more embryos transferred than a younger woman would. However, this increases her risk of multiple pregnancy.
Because of the risks of multiple pregnancy to the babies, the American Society for Reproductive Medicine (ASRM) recommends that women younger than age 35 have no more than two embryos transferred, women ages 35 to 37 have no more than three, women 38 to 40 have no more than four transferred, and women who have had repeated failed cycles or are older than 40 have no more than five embryos transferred in a ZIFT procedure. Since all the eggs transferred in GIFT may not become fertilized, the ASRM recommends one more egg be transferred in each of these age categories. For example, a woman under age 35 could have up to 3 eggs transferred.2 Health professionals in Canada usually follow these recommendations.
Women over 40 have a high rate of embryo loss when using their own eggs. As an alternative, older women can choose to use more viable donor eggs.
What To Think About
ZIFT and GIFT procedures using gametes from both partners account for less than 2% of all ART procedures. The majority of couples in the United States use in vitro fertilization.3 The majority of couples in Canada also use in vitro fertilization.
ART birth rates can be misleading. As a woman ages past her mid-30s, her egg quality and quantity decline, making it increasingly unlikely that an ART procedure using her own eggs will result in pregnancy and a healthy baby. Many women over age 40 choose to use donor eggs, which greatly improves their chances of giving birth to a healthy child.
ZIFT requires two separate procedures. The first procedure is to collect the eggs from the woman's ovaries. The second procedure is done several days later when the fertilized egg (zygote) is placed in her fallopian tube.
If GIFT fails, a doctor does not learn anything about the sperm's ability to fertilize the eggs. With in vitro fertilization, the sperm fertilizes the egg in the laboratory, where a health professional can tell whether fertilization has occurred, and can follow embryo development.
ZIFT and GIFT procedures both cost approximately $7,000 to $8,000 per attempt. In vitro fertilization costs fall within the same range.
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| Author: | Shannon Erstad, MBA/MPH Carrie Henley | Last Updated: August 16, 2006 |
| Medical Review: | Adam Husney, MD - Family Medicine Joy Melnikow, MD, MPH - Family Medicine Kirtly Jones, MD - Obstetrics and Gynecology Femi Olatunbosun, MB, FRCSC - Obstetrics, Gynecology and Reproductive Medicine | |
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| Topic Contents | |
| Treatment Overview | |
| What To Expect After Treatment | |
| Why It Is Done | |
| How Well It Works | |
| Risks | |
| What To Think About | |
| References | |