IVF: How it works
In vitro fertilization, or IVF, refers to a process in which
a woman's egg and a man's sperm are introduced in a
lab petri dish, rather than in the woman's body. The
hoped-for result is an embryo, which will then be
transferred to the woman's uterus. If the embryo
implants, the woman is pregnant.
Because there are so many variables that effect
successful implantation and resulting pregnancy, the
standard has been to try to create more than one
healthy embryo in the lab for transferring back to the
mother's uterus, in order to optimize her odds for
pregnancy. To avoid multiple pregnancies of twins,
triplets, or more, we gauge each patient's and each
embryo's chances for success and then transfer back
as few embryos as possible toward a healthy singleton
pregnancy.
When a woman uses injectable fertility medications,
she may ovulate as few as one or as many as 20 or
more oocytes (eggs.) For the IVF process, her mature
eggs will be retrieved through the use of a small hollow
aspiration needle. The retrieval procedure is painless,
as the patient will be lightly sedated.
The eggs are then put into a liquid, along with the
father's or donor's sperm, in a shallow glass lab dish. It
is normal for some of the eggs to remain unfertilized by
sperm, so creating more eggs will increase your
chances for fertilization. Hence, the use of injectable
fertility medications with IVF. Also, and especially for
older women, the more eggs you create, the greater
your odds at having chromosomally normal, high quality
egg cells available for fertilizing.
Any resulting embryos will be closely observed and
graded according to their appearance. Only those
embryos deemed by the embryologist, the physician,
and the patient to have the best chances for
implantation will be transferred to the woman's uterus.
There are additional assisted reproductive techniques
that are used in conjunction with IVF, such as ICSI,
assisted hatching, blastocyst transfer and PGD, and
each of those topics will be discussed in different
newsletter issues.
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Who Should Use IVF
Improvements in the IVF process have made it one of
the most successful assisted reproductive treatments.
Theoretically, most patients can choose IVF for their
family-building needs, but there are some cases of
infertility that may only respond to IVF.
IVF is most helpful for women with blocked, severely
damaged, or absent fallopian tubes. Also, endometriosis
and male-factor issues tend to respond more favorably
to IVF than IUI. IVF is sometimes the first choice for
couples who have been diagnosed as
having "unexplained" infertility.
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When to Stop Using IVF
Generally, success rates for IVF treatment tend to
range around 30% deliveries per egg retrieval, but that
number can be significantly higher or lower depending
on the individual patient's medical history and age.
Sometimes, especially for cases of unexplained
infertility, an IVF cycle that does not result in a
pregnancy can give us more clues about problems that
can be corrected to bring future success. We may
learn, for example, that a woman's egg reserve is
simply no longer adequate and that she'll be most
successful using donor eggs. Similarly, other advanced
techniques can be performed in conjunction with
subsequent IVF cycles as deemed necessary and
desired.
Again, each patient's situation is unique, and I advise
them accordingly regarding treatment options and
plans. The choices for treatment always remain in the
hands of the patient and couple.
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