In
Vitro Fertilization (IVF)
IVF
has given hope to thousands of couples who otherwise
had no chance of conceiving a genetically related child.
IVF was first successfully performed by Dr.s' Steptoe
and Edwards in England and later in the United States
at the Jones Institute for Reproductive Medicine. IVF
was considered experimental by the American Medical
Association for many years; however it is now an excepted
first line treatment for many of the conditions that
cause infertility.
"In
vitro" literally means "outside of the body"
which describes where fertilization occurs in IVF. The
female undergoes a "stimulation cycle" to
cause the development and maturation of multiple eggs.
The stimulation cycle involves the administration of
gonadotropins (FSH and or HMG) which acts directly upon
the ovaries.
The
female self administers daily injections of gonadotropins
and makes regular visits to the office during the stimulation
cycle to monitor follicular development and check the
estrogen level (estradiol) in the blood. The size of
the follicles is measured using transvaginal ultrasound
and development (quality and size) is accessed using
measurements of the hormone estradiol.
In
an IVF cycle, timing is critical since the eggs must
be retrieved and embryo(s) transferred at the appropriate
time. The female's cycle is controlled using various
medications. Antagon or Lupron are given to "down
regulate" the female's pituitary gland (in the
brain) according to specific protocols. These medications
dramatically lower (Lupron) or block (Antagon) the production
of gonadotropin releasing hormone (GnRh) which stimulates
the production of FSH and luteinizing hormone (LH).
Since the drugs stop the production of FSH, it must
be given by injection to stimulate the development of
multiple eggs.
In
a natural cycle, LH levels rise dramatically to trigger
ovulation once the eggs are mature. GnRH blocks this
surge in an IVF cycle so that ovulation does not occur
until triggered with an injection of hCG. If ovulation
were to occur early, the IVF cycle would be "lost"
since the eggs could not be retrieved.
Some
women cannot produce adequate follicles for many reasons
including ovarian failure or poor ovarian reserve. These
couples often use the eggs from a younger donor (typically
less than 30 years old).
Once
the eggs are mature, she receives an injection of hCG
35-36 hours prior to the scheduled retrieval. The patient
and her partner arrive at the clinic on the day of retrieval
and a sperm sample is collected. The sperm are specially
washed and concentrated in preparation for exposure
to the eggs.
At
retrieval, (usually under anesthesia or in some cases
a sedative is given) and the eggs are retrieved through
the back wall of the vagina using transvaginal guided
ultrasound. The aspirated follicular fluid is immediately
passed to the embryologist who "separates out"
the eggs and places them in a series of specially prepared
fluid media.
The
eggs are then transferred to a Petri dish and the sperm
are introduced. One sperm will fertilize each egg resulting
in embryos which contains the genetic makeup of the
sperm and egg source. In many cases, intracytoplasmic
sperm injection (ICSI) is used to insert one sperm directly
into the egg. Preimplantation genetic diagnosis (PGD)
might by employed if genetic disease is suspected.
The
embryos are transferred to the carefully controlled
environment of the incubator where they remain until
mature, usually 3- 5 days. Five day embryos are termed
blastocyst and are more likely to implant and develop.
Once
the embryos mature, they are transferred to the uterus
in a painless procedure lasting about ten minutes. The
number of embryos transferred depends upon several factors
including their quality, stage of development, and patient
variables. The more embryos transferred, the greater
the chance of multiple births. Progesterone is usually
given to stimulate and support the development of the
endometrium, which is where the embryo attaches.
IVF
success rates vary by practice and are dependent upon
the cause(s) of infertility, the patient's age, presence
of male factor, physician
 and
embryologist variables. The Centers for Disease control
maintains IVF statistics for most programs at their Web
site. It is virtually impossible to compare one center
with another and the American Society of Reproductive
Medicine (ASRM) speaks highly against doing so.
Be
sure and visit the sections on donor egg, intracytoplasmic
sperm injection, and preimplantation genetic diagnosis.
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