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"Test
Tube" Pregnancies (In-Vitro Fertilisation - I.V.F.)
What is "test-tube"
pregnancy (I.V.F)
In 1977, Mr. Steptoe and Dr. Edwards
achieved the first successful human pregnancy by the technique of in-vitro
fertilisation and embryo transfer. This procedure involves fertilizing
an egg outside the body and then transferring the embryo back into the
uterus.
For whom is I.V.F.
advisable
Candidates for I.V.F. are usually
those women with irreparably damaged tubes. I.V.F. can also be the treatment
of last resort in the case of problems like oligospermia, major cervical
mucus hostility factors and certain cases of unexplained infertility.
A woman's age must be considered.
Older women feel additional pressure as they feel their biological clocks
are ticking and time is running out. The majority of I.V.F clinics put
a ceiling on the age for women eligible for this treatment. The general
limit is 38 years.
This very complex procedure (which
has been explained in a very simplistic fashion here), is time-consuming
and expensive. While I.V.F. offers hope to many people, its use is only
indicated for a very small proportion of the infertile population.
How successful is this
treatment
The success rate of pregnancy associated
with this treatment ranges between 15-30%. In the case of a very young
patient with a severe tubal problem, it is worth attempting tubal surgery
first since even the low success of surgery in these circumstances will
probably be greater than the likely success of I.V.F.
What tests are undertaken
before performing I.V.F.
Once the couple has been seen and
considered to be possibly suitable for I.V.F., a series of tests commence
which will include semen analysis, semen culture and assessment of the
menstrual cycle with hormone assays. Depending on the technique that will
be used to retrieve the eggs (oocytes) a preliminary laparoscopy or ovarian
ultrasound scan may be required, so that the accessibility of the ovaries
can be determined.
How is I.V.F. carried
out
A combination of clomiphene and Pergonal
is usually given to promote the maturation of several follicles. The idea
is that if one has several follicles available for egg retrieval, then
if more than one egg is successfully fertilized and transferred back into
the uterus, the odds are greater that at least one of them will successfully
implant. The progress of the growth of the follicles is closely monitored
either by blood and urine tests or by ultrasound measurement of the follicles.
Once the follicles are ready for
ovulation, H.C.G. of 5,000 units is given. The eggs are retrieved
33-36 hours following the H.C.G. injection.
There are two methods which clinics
may use for egg retrieval.
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Laparoscopy. This is carried out under
general anaesthetic. The eggs are retrieved from their follicles using
a very fine suction needle.
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T.U.D.O.R. This stands for Trans-vesical,
Ultrasound Directed Oocyte Recovery. This is an outpatient procedure performed
under a local anesthetic. In this method, a suction probe is guided by
ultrasound control through the bladder. This technique also has the advantage
of being able to retrieve eggs from an inaccessible ovary even if it is
covered by adhesions.
The eggs are now incubated for 4-24
hours in a specially prepared culture medium in order to ensure that adequate
maturation has occurred. 100,000-1,000,000 specially prepared progressively
swimming sperm are then added to the incubated eggs. Fertilisation takes
place within the next 24 hours. 2-3 days later the embryo transfer takes
place. This is a painless procedure and no anaesthetic is required.
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