Assisted Reproductive Technologies (ART)
Assisted Reproductive Technologies or ART, include several different techniques
or procedures now available to help couples achieve fertility after other surgical
and hormonal methods have failed. These procedures employ techniques that retrieve
eggs from the ovary and reimplant them. Fertilization
may occur either in the laboratory or in the uterus.
For many couples, ART offers the best hope of achieving pregnancy. Following
is a description of each of these procedures and how they work:
In Vitro Fertilization (IVF)
In Vitro Fertilization is probably the best known and most widely used ART procedure.
For well over a decade, IVF has allowed infertile couples the chance to conceive
and bear children. The best candidates for IVF are women with damaged fallopian
tubes.
IVF is a four-stage procedure. The beginning
of this process involves ovarian stimulation to produce several mature eggs
that can be harvested from the ovary before they have been released from the
follicles, and the monitoring and collection of eggs. Multiple eggs are removed
from the woman and placed in a special medium for two to three hours. The male
semen is processed, using different techniques
to obtain a vigorous motile sperm. The prepared sperm is then introduced into
the medium containing the egg(s).
Many of these eggs will fertilize and develop
into embryos, which are then transferred back
into the woman's uterus through a simple procedure
that requires no anesthesia. In most cases, egg recovery is preceded by a period
during which the woman receives daily hormone medications to stimulate the growth
of multiple eggs. In some instances, however, it may be possible to accomplish
IVF without the use of these ovulation induction
medications.
Preimplantation Genetic Diagnosis (PGD) PGD is a process whereby a single blastomere from an 8-cell embryo (three
days post fertilization) is removed,
fixed, and subjected to a number of DNA probes. We can now determine if an embryo
is a male or a female, or has an extra chromosome,
i.e. 13, 16, 18, 21, 22. The results can be obtained within 24 hours which allows
the laboratory another 24 hours to grow the normal embryos
to Blastocyst (five days post fertilization)
for embryo transfer.
Gamete Intra-Fallope Transfer (GIFT)
GIFT is an ART procedure developed to assist women, particularly those who have
normal fallopian
tubes, but there is unexplained
infertility. In these cases it can be difficult
to determine if the sperm and egg
ever meet, so this procedure allows for a site where fertilization
is most likely to occur.
This technique is similar to IVF with the
exception that the harvested eggs are not fertilized. The eggs are mixed with
the washed and capacitated sperm and immediately
placed directly into the woman's fallopian tubes through a laparoscope (a long
thin catheter), thus the sperm and egg are placed exactly where they would be
in natural fertilization. Fertilization then occurs in the woman's fallopian
tubes, after which they move down into the uterus
for implantation according to a "normal" timetable.
Zygote Intra-Fallope Transfer (ZIFT)
This procedure is a combination of IVF and
GIFT. The eggs are fertilized with washed and
capacitated sperm in the laboratory as in the
IVF procedure, but then the beginning-stage embryos
are placed directly into the patient's fallopian
tubes as in the GIFT procedure. This blending of IVF and GIFT technique
offers the advantage of confirming that fertilization
has occurred and the eggs can be examined for defects before implantation.
This procedure also provides the natural environment of the fallopian tubes
for the very early conceptus.
Donor Oocyte Program (DOP)
Age, is the most important determinant when a woman uses her own eggs. Rates
for ART are relatively high for both pregnancies and live births among women
in their 20's but they decline after 30 and go sharply downward toward the end
of the decade and afterward. The patients who can most benefit from oocyte
donation are those who lack ovarian function.
The use of donor eggs has made it possible
for many older women, (Success rates using donor
oocyte's depend on the age of the donor, not the age of the recipient.)
This procedure provides healthy eggs from either a known or anonymous donor
to women who are unable to utilize their own eggs to achieve pregnancy. fertilization
can be with the sperm of the recipient's husband to the fallopian
tubes of the recipient (GIFT), or the eggs
can be fertilized In Vitro with the resulting embryos
transferred to the recipient's uterus (IVF)
or to her fallopian tubes (ZIFT).
Embryo Cryopreservation
In cases where more eggs develop into embryos
than are going to be transferred to the patient, the couple will have the option
of cryopreservation, or freezing, of the embryos
for transfer into the woman's uterus at a later
date.
Cryopreservation is used to minimize the
risk of multiple births, which increases dramatically if more than four or five
embryos are replaced. Once embryos are frozen in liquid nitrogen and stored,
viability will remain unchanged for long periods. With current freezing and
storage methods, 60 to 80 percent of embryos will be viable after thawing. One
of the advantages of embryo cryopreservation is that transfer of the thawed
embryo may occur in a natural ovulatory cycle.
Intracytoplasmic sperm injection (ICSI)
is a highly sophisticated technique for injecting one single sperm into an egg
using microscopic and micromanipulation instruments. In men with low sperm
count, low motility or a high number of abnormal sperm, this technique has
proven to be a highly successful remedy. Combined with IVF
or ZIFT, the procedure of ICSI is able
to achieve a high rate of fertilization
and normal embryo development. ICSI has
even been successful in cases where sperm must be taken directly from the testes
(testicular biopsy) due to the absence of sperm in the ejaculate
or a previous vasectomy. ICSI is also the best choice when other andrology tests
identify a possible problem with sperm function.
Assisted Hatching
This is a procedure of making a tiny hole in the membrane surrounding the embryo
before implanting to assist it in attaching to the uterus.
This thinning the membrane of the fertilized egg may increase implantation
rates in eggs from certain women, such as those over age 40.