Assisted
Reproductive Technologies (ART)
Many
times couples cannot become pregnant without specialized
medical care. As the name implies, ART procedures are
those that employ advanced technologies to help couples
become pregnant. This page includes brief descriptions
of various ART procedures with links to more detailed
discussions.
ART
procedures include in
vitro fertilization, intracytoplasmic
sperm injection, donor
egg IVF, preimplantation genetic
diagnosis, assisted hatching, and blastocyst transfer,
where physicians, embryologists, and other technicians
utilize their training, skills, and equipment to cause
eggs to fertilize, develop, and implant in the uterus.
In
vitro fertilization is an ART procedure that was first
successfully performed in 19789 in England by doctors
Steptoe and Edwards and later in the United States by
Howard Jones, MD and Georgianna Jones, MD at the Jones
Institute for Reproductive Medicine in Norfolk, VA.
In
in vitro fertilization the female receives medication
causing her ovaries to produce numerous eggs that will
be retrieved from the ovarian follicles by the reproductive
specialist. The partner's sperm are obtained by masturbation
and combined with the eggs, "in vitro, or outside
of the body". After fertilization, the resultant
embryos are placed in an incubator until they are ready
for transfer back to the uterus. IVF pregnancy rates
have improved dramatically over the last several years
and vary by infertility clinic.
Intracytoplasmic
sperm injection (ICSI) was introduced in early 1990's
and made it possible for "infertile" men to
produce genetically related children. Before ICSI the
only option for couples with male infertility was to
use a sperm donor.
ICSI
involves injecting a single sperm into the egg retrieved
during an IVF cycle.
Sperm can usually be obtained from the ejaculate even
if the sperm count is very low. In cases where there
are no viable sperm in the ejaculate, sperm can often
be retrieved from the male reproductive tract. Testicular
sperm aspiration (TESA) involves retrieving sperm directly
from the testicles and microepididymal sperm aspiration
involves taking sperm from the tubes known as the epididymus.
Donor
egg involves an IVF cycle where another woman's eggs
are combined with the partner's sperm. The resultant
embryos are placed in an incubator until ready for transfer
back to the recipient mother's uterus. The baby will
have the genetic makeup of the egg donor and male partner.
The recipient mother experiences the joy of pregnancy
and delivery.
Donor
egg is recommended for women who have reduced ovarian
reserve or ovarian failure. It is also used in some
cases of infertility from unexplained causes and in
older women.
Zygote
intrafallopian transfer (ZIFT) is a procedure similar
to IVF. In ZIFT, the embryo is surgically placed in
the end of the fallopian tube, where fertilization normally
takes place. Success rates for ZIFT are not superior
to IVF and the procedure is more expensive.
Gamete
intrafallopian transfer (GIFT) is another procedure
that is similar to IVF. In GIFT, the eggs are combined
with the sperm in the distal end (near the uterus) of
the fallopian tube which is where fertilization occurs.
ZIFT is different in that it involves placing an embryo
in the end of the tube instead of the gametes (sperm
and egg). GIFT is more expensive than IVF because it
involves laparoscopic surgery and many studies show
lower success rates compared to IVF. The incidence of
tubal pregnancies is also higher with GIFT and ZIFT.
Some couples choose GIFT for religious reasons because
fertilization occurs in the body, not in a Petri dish
as in IVF.
Preimplantation
genetic diagnosis (PGD) allows the IVF team to screen
the embryos for certain birth defects before they are
replaced into the mother's uterus. It is now possible
to screen for many diseases including sickle cell anemia,
Tay-Sahs, hemophilia and others. A small amount of genetic
material is removed from the embryo and examined using
techniques known as fluorescent in situ hybridization
or PCR. This procedure does not damage the embryo. Only
"disease free" embryos are transferred back
to the mother thus eliminating embryos carrying the
genetic disease.
Assisted
hatching is an ART procedure that helps embryo's "hatch"
and successfully implant in the uterus. In assisted
hatching, a small hole is made in the membrane surrounding
the embryo, known as the zona pellucida. Piercing the
membrane makes it easier for the embryo to break free
and ultimately attach to the uterine wall. Assisted
hatching is used in cases of unexplained infertility,
in older couples, and other situations where the embryologist
and physician deem it appropriate.
A
blastocyst is a type of embryo that has been incubated
for at least five days and has differentiated into two
different cell types. Embryos that survive to the blastocyst
stage are usually more "hearty" and produce
higher pregnancy rates. Since blastocysts are more likely
to survive, fewer can be transferred thus reducing the
occurrence of high order (3 or more) multiple births.
The
next several years should bring the addition of several
new ART procedures that will help infertile couples.
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