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Treatment
of infertility
Today,
their is a wide range of medical help that can be offered to infertile
couple. In thew past five to ten years, there has been an explosion
of new information about infertility and great advances, in fertility
treatment. These new therapies include advances in hormonal treatment,
a wider acceptance of donor insemination, the development of intrauterine
insemination (IUI) and advances in micro surgery and laser surgery.
However, the most important advances have been made in assisted
reproductive technologies (ART). ART includes in vitro fertilization
(IVF), gamete intrafallopian transfer (GIFT) and intracytoplasmic
sperm injection (ICSI). Progress has also been made in understanding
the psychosocial impact of infertility and in helping couples
to manage their worries and emotions through contact with other
infertile couples, support groups and counseling.
Correct diagnosis is acrucial step in determining appropriate
therapy, and a variety of procedures can be used, ranging from
simple blood tests to more complicated analytical methods. Furthermore,
as fertility often has several causes, many factors must be considered.
Once the diagnosis is established, treatment can be tailored specifically
to the individual needs of the couple.
Total infertility is rear and the inability to conceive is generally
the result of some degree of subfertility. 'Infertility' can therefore
often be overcome. In some cases, surgical correction may be appropriate;
in others referral for hormonal treatment or ART may be required.
Even in the most extreme cases, where the woman has a premature
menopause or the man has a complete lack of sperm, solutions such
as sperm and egg donation can be considered.
However, society seems ambivalent about accepting infertility
as a legitimate health problem. In Europe, provision for infertility
treatment is often limited by healthcare budgets or subject to
marked regional variations in availability and/or accessibility.
The use of donor eggs or sperm has created great concern and are
still matter of heated debate and the use of some forms of ART,
such as cryopreservation, has been questioned. Cryopreservation
is accepted in some countries but banned in others. Probably no
other medical procedures have been subject to such intense religious,
moral and social scrutiny as those of assisted reproduction.
Treatment
of female infertility
Several options for treatment are offered to patients depending
upon the type of infertility diagnosed. The vast majority of female
patients are successfully treated with the administration of drugs
such as clomiphene citrate, gonadotropins or bromocriptine. Surgery
can also be a means to repair damage to the reproductive organs
such as those caused by endometriosis and infectious diseases.
The main approaches to the treatment of the female infertility
are given below.
- Ovulation
induction (OI)
- Assisted
reproductive technology (ART)
- Intrauterine
insemination (IUI)
- Intravaginal
insemination
- In
Vitro fertilization (IVF)
- Gamete
intrafallopian transfer (GIFT)
The female reproductive cycle is regulated by hormones under the
control of the hypothalamus, the pituitary gland and the ovaries.
If this basic control system does not work correctly, ovulation
will be disturbed or absent. Ovulatory disorders are characterized
by anovulation (complete failure to ovulate) or infrequent and/or
irregular ovulation.
The WHO has adopted a treatment-oriented classification of anovulating
patients:
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Group
I patients have hypothalmic-pituitary failure. They are amenorrheic
and lack both follicle stimulating hormone (FSH) and luteinizing
hormone (LH).
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Group
II patients have hypothalmic-pituitary dysfunction and present
with a variety of cycle disorders including amenorrhoea, oligomenorrhoea
and luteal phase deficiencies. About 97% of anovulatory patient
fall into this group, including polycystic ovarian disease
(PCOD, a condition commonly characterized by hirsutism, obesity,
menstrual abnormalities, infertility and enlarged ovaries;
thought to reflect excessive androgen secretion of ovarian
origin), which is thought to be the most common cause of ovarian
dysfunction.
Ovulation
induction (OI) aims to correct hormonal imbalances, allowing where
possible, monoovulation to occur. More than 80% of infertile women
anatomical disorders are treated successfully with fertility agents
that promote the growth and development of ovarian follicles vis
stimulation of FSH and LH.
Agents
most commonly used for ovulationinduction are:
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Clomiphene
citrate, acting on the hypothalamus to increase the release
of gonadotropin releasing hormone (GnRH), which, in turn,
stimulate the pituitary gland to release FSH and LH.
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Gonadotropins
(FSH and LH acting directly on the ovary, promoting follicular
development and hCG triggering ovulation after follicular
stimulation).
In
WHO Group I patients, Gonadotropin therapy with both FSH and LH
is required for follicular development and ovulation. WHO Group
II patients may respond to clomiphene citrate. FSH treatment is
normally reserved for those who do not respond to clomiphene.
OI
is usually combined with timed intercourse or with artificial
insemination (also called intrauterine insemination - IUI) in
order to increase the probability of successful fertilization.
If conception has not taken place after approximately three to
five cycles with clomiphene citrate and a further three to five
cycles with Gonadotropin treatment, the patient may be referred
for ART. The number for clomiphene citrate/Gonadotropin treatment
courses is related to the type of infertility, the result of the
investigations and reimbursement schemes practiced in each individual
country.
FSH
is effective in ovarian stimulation. Human chorionic gonadotropin
(hCG) injections are used in conjunction with FSH to provoke egg
release (hCG is given to mimic the natural LH surge). A frequent
adjunct to FSH therapy is synthetic luteinizing hormone releasing
hormone (LHRH) analogues which work by suppressing the ovaries.
In their suppressed state, the ovaries are more receptive to FSH
therapy and higher quality eggs are produced as a result. This
is particularly useful for women with PCOD not responding to FSH
alone.
Bromocriptine
is a useful agent in the treatment of hyperprolactinemia, a condition
where there is excess of the hormone prolactin in the blood. This
condition results in the suppression of GnRH release contributing
to anovulation.
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Assisted reproductive technologies (ART) |
The term ARt is used to describe all the methods of artificially
assisted conception and refers to several different methods designed
to overcome barriers to natural fertilization. The earlier forms
of ART were those designed to assist in cases of male infertility,
such as assisted transfer of sperms into the vagina or uterus.
Intrauterine insemination (IUI) is still widely used today, however
mainly for specific cases. Since the first successful birth after
IVF in the UK in 1978, many techniques have been developed and
success rates have increased dramatically.
Today, ART is called upon for cases of infertility due to anatomical
problems (e.g. blocked fallopian tubes), severe male factors (sperm
defects, low sperm counts, male and female antisperm antibodies),
widespread endometriosis and unexplained infertility. One of these
techniques, In Vitro fertilization (IVF) has now been widely practiced
for more than 15 years and is the starting point for most ART
treatments. Current ART techniques are summarized and described
in detail below.
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Intrauterine insemination (IUI) |
Intrauterine insemination is one of the earlierest form of ART
and involves the assisted transfer of sperm into the uterus by
means of a catheter directed through the cervix. IUI was originally
designed to assist in cases of male infertility. The premise of
IUI is that the sperm can reach and fertilize the egg more easily
if placed in the uterine cavity. In the 1960s, physicians attempting
to enhance the chances of pregnancy injected fresh, untreated
sperm (sperm plus seminal fluid) directly into the uterus at the
time of ovulation. It was found that when more than 0.2ml of sperm
was injected, a serious shock-like reaction insured, later discovered
to be a reaction to the prostaglandins found in seminal fluid.
Women are protected against this during sexual intercourse by
the cervical mucus. The early result of this practice were dismal.
However, after the practice of washing the sperm became more common,
pregnancy rates using this method increased. IUI is still widely
used today but it is limited to assisting women with deficient
cervical mucus, which is either poor in quality or hostile to
sperm and to women with mild endometriosis.
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Intravaginal insemination (IVI) |
Intravaginal insemination, again a practice, which has been used
for sometime, is now used for donor sperm procedures, artificial
insemination partner (AIP) or artificial insemination donor (AID).
IVI offers no benifits over normal sexual intercourse, in the
case of AIP, but can be useful to circumvent male impotence.
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In Vitro fertilization (IVF) |
In Vitro fertilization is the process by which eggs (oocytes)
and sperm are mixed together outside the body (i.e. in vitro).
Following fertilization, resulting embryos are transfered to the
woman's uterus 2-5 days later.
The IVF process can be summerized in the following five steps:
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The
ovaries are stimulated with FSH, in order to cause ripening
of several follicles. This is called controlled ovarian
stimulation (COS). Successful COS requires very precise
day-by-day adjustment of the normal dose. This can only
be achieved with the use of FSH in combination with GnRH
analogues, allowing the continuous growth of a large number
of follicles whilst preventing a spontaneous LH surge through
the suppression the natural secretion of FSH and particularly
LH. A premature LH surge can cause early ovulation and jeopardize
the success of the treatment cycle.
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When
ultrasound monitoring indicates that the follciles are large
enough to contain an egg that has matured suffeciently,
hCG is injected to induce final follicular maturation.
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The
eggs are collected about 36 hours after the hCG injection.
Egg collection is usually carried out via the vagina under
ultrasound guidence utilizing a long hollow needle, although
egg collection by laparoscopy (via the abdominal wall) may
occasionally be used.
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The
eggs are then fertilized with the sperm and the first cell
divisions are monitored. Embryos are transferred into the
uterine cavity 2-5 days after in vitro fertilization.
Usually
more then one embryo is transferred to increase the chances of
a successful pregnancy. To avoid the risk of multiple births,
it is generally recommended that a maximum of two embryos be transferred.
In november 1999, the American Society of reproductive Medicine
(ASRM) released guidelines on the number of embryos to be transferred.
Under british and german law, a maximum of three embryos can be
placed in the uterus at one time, although there is no similar
restrictions governing other countries. With the introduction
of cryopreservation, excess embryos can be stored for future cycles
thus avoiding the patient having to go through ovarian stimulation
and egg collection unnecessarily. Cryopreservation is highly regulated
in a number of countries.
The
success rate of IVF has remained fairly constant for the last
six years at around 15%. The success rate falls dramatically after
age 40 when only 5% of women treated with their own eggs can expect
a live birth.
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Gamete
intrafallopian transfer (GIFT)
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Gamete intrafallopian transfer follows the same procedures as IVF,
except that fertilization ocurs in the body (in vivo). The eggs
and sperms are placed directly in the fallopian tube where the fertilization
can occur. |