In vitro fertilisation

In vitro fertilisation
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(Redirected from In-vitro fertilization)

"IVF" redirects here. For other uses, see IVF (disambiguation).
"Test tube baby" redirects here. For other uses, see Test tube baby (disambiguation).
In vitro fertilisation (IVF) is a process by which egg cells are fertilised by sperm outside the womb, in vitro. IVF is a major treatment in infertility when other methods of assisted reproductive technology have failed. The process involves hormonally controlling the ovulatory process, removing ova (eggs) from the woman's ovaries and letting sperm fertilise them in a fluid medium. The fertilised egg (zygote) is then transferred to the patient's uterus with the intent to establish a successful pregnancy. The first "test tube baby", Louise Brown, was born in 1978.

The term in vitro, from the [Latin] root meaning within the glass, is used, because early biological experiments involving cultivation of tissues outside the living organism from which they came, were carried out in glass containers such as beakers, test tubes, or petri dishes. Today, the term in vitro is used to refer to any biological procedure that is performed outside the organism it would normally be occurring in, to distinguish it from an in vivo procedure, where the tissue remains inside the living organism within which it is normally found. A colloquial term for babies conceived as the result of IVF, test tube babies, refers to the tube-shaped containers of glass or plastic resin, called test tubes, that are commonly used in chemistry labs and biology labs. However, in vitro fertilisation is usually performed in the shallower containers called Petri dishes. (Petri-dishes may also be made of plastic resins.) However, the IVF method of Autologous Endometrial Coculture is actually performed on organic material, but is yet called in vitro. This is used when parents are having infertility problems or they want to have multiple births.
Contents[hide]
1 Indications
2 Method
2.1 Ovarian stimulation
2.2 Egg retrieval
2.3 Fertilisation
2.4 Selection
2.5 Embryo transfer
3 Pregnancy rates
3.1 Effect of stress
3.2 Live birth rate
4 Complications
4.1 Birth defects
5 Cryopreservation
5.1 Embryo cryopreservation
5.2 Oocyte cryopreservation
5.3 Ovarian tissue cryopreservation
6 Variations
7 Embryo & Oocyte Donation
8 Acupuncture
8.1 Acupuncture Mechanisms
8.2 Electro-acupuncture in oocyte retrieval for IVF
9 History
10 Ethics
10.1 Issues
10.2 Pregnancy past menopause
10.3 Same-sex couples
11 Religious objections
12 Availability and utilisation
13 See also
14 References
15 Further reading
16 External links
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[edit] Indications
Initially IVF was developed to overcome infertility due to problems of the fallopian tube, but it turned out that it was successful in many other infertility situations as well. The introduction of intracytoplasmic sperm injection (ICSI) addresses the problem of male infertility to a large extent. (Male infertility consists of failure to produce sperm.)
For IVF to be successful it may be easier to say that it requires healthy ova, sperm that can fertilise, and a uterus that can maintain a pregnancy. Due to the costs of the procedure, IVF is generally attempted only after less expensive options have failed.
This means that IVF can be used for females who have already gone through menopause. The donated oocyte can be fertilised in a crucible. If the fertilisation is successful, the zygote will be transferred into the uterus, within which it will develop into an embryo.

[edit] Method

[edit] Ovarian stimulation
Treatment cycles are typically started on the third day of menstruation and consist of a regimen of fertility medications to stimulate the development of multiple follicles of the ovaries. In most patients injectable gonadotropins (usually FSH analogues) are used under close monitoring. Such monitoring frequently checks the estradiol level and, by means of gynecologic ultrasonography, follicular growth. Typically approximately 10 days of injections will be necessary. Spontaneous ovulation during the cycle is typically prevented by the use of GnRH agonists or GnRH antagonists, which block the natural surge of luteinising hormone (LH).

[edit] Egg retrieval
Main article: Transvaginal oocyte retrieval
When follicular maturation is judged to be adequate, human chorionic gonadotropin (hCG) is given. This agent, which acts as an analogue of luteinising hormone, would cause ovulation about 42 hours after injection, but a retrieval procedure takes place just prior to that, in order to recover the egg cells from the ovary. The eggs are retrieved from the patient using a transvaginal technique involving an ultrasound-guided needle piercing the vaginal wall to reach the ovaries. Through this needle follicles can be aspirated, and the follicular fluid is handed to the IVF laboratory to identify ova. It is common to remove between ten and thirty eggs. The retrieval procedure takes about 20 minutes and is usually done under conscious sedation or general anesthesia.

[edit] Fertilisation
In the laboratory, the identified eggs are stripped of surrounding cells and prepared for fertilisation. In the meantime, semen is prepared for fertilisation by removing inactive cells and seminal fluid. If semen is being provided by a sperm donor, it will usually have been prepared for treatment before being frozen and quarantined, and it will be thawed ready for use. The sperm and the egg are incubated together at a ratio of about 75,000:1 in the culture media for about 18 hours. In most cases, the egg will be fertilised by that time and the fertilised egg will show two pronuclei. In certain situations, such as low sperm count or motility, a single sperm may be injected directly into the egg using intracytoplasmic sperm injection (ICSI). The fertilised egg is passed to a special growth medium and left for about 48 hours until the egg consists of six to eight cells.

[edit] Selection
Laboratories have developed grading methods to judge oocyte and embryo quality. Typically, embryos that have reached the 6-8 cell stage are transferred three days after retrieval. In many American and Australian programmes[citation needed], however, embryos are placed into an extended culture system with a transfer done at the blastocyst stage at around five days after retrieval, especially if many good-quality embryos are still available on day 3. Blastocyst stage transfers have been shown to result in higher pregnancy rates.[1] In Europe, transfers after 2 days are common. Preimplantation Genetic Diagnosis (PGD) procedures may be performed prior to transfer.[2]

[edit] Embryo transfer
Main article: Embryo transfer
Embryos are graded by the embryologist based on the number of cells, evenness of growth and degree of fragmentation. The number to be transferred depends on the number available, the age of the woman and other health and diagnostic factors. In countries such as the UK, Australia and New Zealand, a maximum of two embryos are transferred except in unusual circumstances. In the UK and according to HFEA regulations, a woman over 40 may have up to three embryos transferred, whereas in the USA, younger women may have many embryos transferred based on individual fertility diagnosis. Most clinics and country regulatory bodies seek to minimise the risk of pregnancies carrying multiples. The embryos judged to be the "best" are transferred to the patient's uterus through a thin, plastic catheter, which goes through her vagina and cervix. Several embryos may be passed into the uterus to improve chances of implantation and pregnancy.

[edit] Pregnancy rates
Pregnancy rate is the success rate for pregnancy. For IVF, it is the percentage of all attempts that lead to pregnancy, which generally refers to treatment cycles where eggs are retrieved and fertilised in vitro. Statistics referring to "pregnancy" may refer to just a positive pregnancy test, and not necessarily "viable pregnancy" which implies the detection of a fetal heart beat. Pregnancies that are delivered with a viable baby is called live birth rate. Increasingly a distinction is also made between singleton and multiple pregnancies as multiple pregnancies, specifically more than twins, should be avoided because of the associated maternal and fetal risks.
With enhanced technology, the pregnancy rates are substantially better today than a couple of years ago. In 2006, Canadian clinics reported an average pregnancy rate of 35%.[3] A French study estimated that 66% of patients starting IVF treatment finally succeed in having a child (40% during the IVF treatment at the center and 26% after IVF discontinuation). Achievement of having a child after IVF discontinuation was mainly due to adoption (46%) or spontaneous pregnancy (42%).[4]

[edit] Effect of stress
According to a 2005 Swedish study published in the Oxford Journal Human Reproduction, 166 women were monitored starting one month before their IVF cycles and the results showed no significant correlation between psychological stress and their IVF outcomes. The study concluded with the recommendation to clinics that it might be possible to reduce the stress experienced by IVF patients during the treatment procedure by informing them of those findings. While psychological stress experienced during a cycle might not influence an IVF outcome, it is possible that the experience of IVF can result in stress that leads to depression. The financial consequences alone of IVF can influence anxiety and become overwhelming. However, for many couples, the alternative is infertility, and the experience of infertility itself can also cause extreme stress and depression.

[edit] Live birth rate
Live birth rate is the percentage of all IVF cycles that lead to live birth, and is the pregnancy rate adjusted for miscarriage and stillbirth. These percentages are for successful pregnancies, regardless of the number of children born, as twins and larger multiple-order births are more common in IVF cycles.
In 2006, Canadian clinics reported a live birth rate of 27%.[3] A summary of 2006 reports from US clinics for cycles that did not involve donor eggs gave success rates varied widely by the age of the prospective mother, with a peak at 42.6% for 27-year-olds. Rates for younger patients were slightly lower, with a success rate of 35.3% for those 21 and younger, the youngest group evaluated. Success rates for older patients were also lower and decrease with age, with 37-year-olds at 27.4% and no live births for those older than 48, the oldest group evaluated. [5]
IVF attempts in multiple cycles result in increased cumulatve live birth rates. Depending on the demographic group, one study reported 45% to 53% for three attempts, and 51% to 71% for six attempts.[6]

[edit] Complications
The major complication of IVF is the risk of multiple births. This is directly related to the practice of transferring multiple embryos at embryo transfer. Multiple births are related to increased risk of pregnancy loss, obstetrical complications, prematurity, and neonatal morbidity with the potential for long term damage. Strict limits on the number of embryos that may be transferred have been enacted in some countries (e.g., England) to reduce the risk of high-order multiples (triplets or more), but are not universally followed or accepted. Spontaneous splitting of embryos in the womb after transfer can occur, but this is rare and would lead to identical twins. A double blind, randomised study followed IVF pregnancies that resulted in 73 infants (33 boys and 40 girls) and reported that 8.7% of singleton infants and 54.2% of twins had a birth weight of <>