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In Vitro Fertilization (IVF)
In order for
pregnancy to occur, an egg has to be released from the ovary
and unite with a sperm. Normally this union, called fertilization,
occurs within the fallopian
tube, which joins the uterus (womb) to the ovary. However,
in IVF the union occurs in a laboratory after eggs and sperm
have been collected. Embryos are then transferred to the uterus
to continue growth.
Candidates
Both fallopian tubes are absent or blocked due to surgery
or tubal pregnancy) or infection (STD, or Tuberculosis)
Endometriosis
Reduced sperm count or motility (IVF can be normally performed
for counts which are more than 5 million per ml. For counts
less than 5 million per ml. ICSI is a better option.) Patients
where all other treatments such as ovulation induction with
intra uterine insemination have
proven unsuccessful.
Patients with unexplained infertility where all the investigations
performed on the couple are normal, but who still do not conceive
with routine treatments.
Patients who have failed to become pregnant inspite of all
routine treatments of infertility.
Patients who want to become pregnant by the procedure of embryo
and egg donation. In our unit, the success rates of IVF are
in the region of 20 to 30%, which are comparable to the leading
units in the world.
Procedure
There are five major steps in the IVF and embryo transfer
sequence:
1. Monitor the development of ripening egg(s) in the
ovaries
2. Collection of eggs
3. Obtaining the sperm
4. Putting the eggs and sperm together in the laboratory,
and providing correct conditions for fertilization and early
embryo growth
5. Transferring the embryos into the uterus
To control the timing of egg ripening and to increase the
chance of collecting substantial number of eggs, fertility
drugs are prescribed according to each individual case. Before
dertemining the egg retreival schedule, we perform an ultrasound
of the ovaries to check the development of eggs and a blood/urine
test to measure hormone levels.
The Egg Retrieval Process
The retrieval procedure to obtain the eggs is performed trans-vaginally
using a hollow needle guided by the ultrasound image (this
is completely comfortable under adequate sedation and local
anesthesia). Eggs are gently removed from the ovaries using
the needle. This is called "follicular aspiration." Its timing
is crucial because the egg will not develop properly if it
is collected too early; if too late, the egg also may develop
poorly or may have already been released from the ovary and lost.
The eggs are immediately identified by our embryologists in
our special IVF laboratory. They are placed with the sperm
in incubators to allow fertilization to take place. The eggs
are examined carefully at intervals to ensure that fertilization
and cell division have taken place; the fertilized eggs are
now called embryos.
Embryos are usually placed in the wife's uterus 2 or 3 days
after egg retrieval. A speculum is inserted into the vagina
to expose the neck of the womb (cervix). The embryos are suspended
in a tiny drop of fluid and then very gently introduced through
a catheter into the womb,
often under ultrasound guidance. The transfer is followed
by a resting period, blood tests and possibly ultrasound examinations
to verify if pregnancy has been established.
To summarize, the IVF procedure consists of:
A Controlled Ovarian stimulation with drugs (GNRH Analogues
and Gonadotrophins) to produce many eggs.
B Monitoring of follicles and egg development with
the aid of vaginal sonography and serial Estradiol hormone
estimation.
C Administration of HCG injection, (Human Chorionic
Gonadotrophins) when the two leading follicles are 18mm in
diameter.
D Oocyte or egg retrieval under short general anesthesia,
35 to 37 hours after HCG injection.
E Identification and isolation of eggs in the laboratory.
F Sperm collection and processing in the lab.
G Fertilization of the egg with the sperm.
H Embryo formation 2 to 5 days after fertilization.
I Embryo transfer of good quality embryos back to the
womb, after 2(four cell embryo), 3 (six-eight cell embryo)
or 5 (blastocyst stage) days after egg removal.
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