In vitro fertilisation: Difference between revisions
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Revision as of 16:20, 9 August 2012
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [5]
Overview
In vitro fertilization[1] (IVF) is a technique in which egg cells are fertilised by sperm outside the woman's 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.
"In vitro"
The term in vitro, from the Latin root meaning in 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.
History
On the basis of the findings of Min Chueh Chang's application of in vitro fertilisation to animals, the technique was developed for humans in the United Kingdom by Patrick Steptoe and Robert Edwards. The first "test-tube baby", Louise Brown, was born in Oldham, England, as a result on July 25, 1978 amid intense controversy over the safety and morality of the procedure.[2]
Subhash Mukhopadhyay became the first physician in India, and the second in the world after Steptoe and Edwards, to perform in vitro fertilisation resulting in a test tube baby "Durga" (alias Kanupriya Agarwal) on October 3 1978. Facing social ostracism, bureaucratic negligence, reprimand and insult instead of recognition from the Marxist West Bengal government and refusal of the Government of India to allow him to attend international conferences, Mukhopadhyay committed suicide in his Calcutta residence in 1981.
Major pioneering developments in IVF also occurred in Australia under the leadership of Carl Wood, Alan Trounson and Ian Johnston.[3][4] The world's third IVF baby, Candice Reed was born on June 23, 1980 in Melbourne, Australia.
The first successful IVF treatment in the USA (producing Elizabeth Jordan Carr) took place in 1981 under the direction of Doctors Howard Jones and Georgeanna Seegar Jones in Norfolk, Virginia. Since then IVF has exploded in popularity, with as many as 1% of all births now being conceived in-vitro, with over 115,000 born in the USA to date. At present, the percentage of children born after IVF or intracytoplasmic sperm injection (ICSI) has been up to 4% of all babies born in Denmark.
Jane Mohr, 38, of Manhattan Beach Calif., gave birth to the nation's first set of triplets born 21 months apart due to in vitro fertilisation (IVF) and long-term embryo storage. Jane gave birth November 29, 1988 to two daughters, Mollie McKenna and Hannah Christina Mohr, nearly two years after the birth of her son, Cooper Patrick Mohr.
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.
Thus, for IVF to be successful it may be easier to say that it requires healthy ova, sperm that can fertilize, and a uterus that can maintain a pregnancy. Cost considerations generally place IVF as a treatment when other less expensive options have failed.
This means that IVF can be used for females who have already gone through pregnancy. The donated oocyte can be fertilised in a crucible. If the fertilisation is successful, the fertilised egg will be transferred into the uterus, within which it will develop into an embryo.
Method
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. Spontanenous ovulation during the cycle is prevented by the use of GnRH agonists or GnRH antagonists, which block the natural surge of luteinizing hormone (LH).
Oocyte retrieval
When follicular maturation is judged to be adequate, human chorionic gonadotropin (β-hCG) is given. This agent, which acts as an analogue of luteinizing hormone, would cause ovulation about 36 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. The retrieval procedure takes about 20 minutes and is usually done under conscious sedation or general anesthesia.
Fertilization
In the laboratory, the identified eggs are stripped of surrounding cells and prepared for fertilisation. In the meantime, semen is prepared for fertilization by removing inactive cells and seminal fluid. The sperm and the egg are incubated together (at a ratio of about 75,000:1) in the culture media for about 18 hours. By that time fertilization should have taken place and the fertilised egg would show two pronuclei. In situations where the sperm count is low, a single sperm is 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 has reached the 6-8 cell stage.
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, however, embryos are placed into an extended culture system with a transfer done at the blastocyst stage, especially if many good-quality day-3 embryos are available. Blastocyst stage transfers have been shown to result in higher pregnancy rates.[5]. In Europe, day-2 transfers are common.
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. For instance, a woman over 35 may have up to three embryos transferred. This is to limit the number of multiple pregnancies. 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.
Post-transfer
The patient has to wait two weeks before she returns to the clinic for the pregnancy test. During this time she may receive progesterone—a hormone that keeps the uterus lining thickened and suitable for implantation. Many IVF programmes provide additional medications as part of their protocol.
Success rates
While the overall live birth rate via IVF in the U.S. is about 27% per cycle (33% pregnancy rate), the chances of a successful pregnancy via IVF vary widely based on the age of the woman (or, more precisely, on the age of the eggs involved). [6] Where the woman's own eggs are used as opposed to those of a donor, for women under 35, the pregnancy rate is commonly approximately 43% per cycle (36.5% live birth), while for women over 40, the rate falls drastically - to only 4% for women over 42. [7] Other factors that determine success rates include the quality of the eggs and sperm, the duration of the infertility, the health of the uterus, and the medical expertise. It is a common practice for IVF programmes to boost the pregnancy rate by placing multiple embryos during embryo transfer. A flip side of this practice is a higher risk of multiple pregnancy, itself associated with obstetric complications.
IVF programmes generally publish their pregnancy rates. However, comparisons between clinics are difficult as many variables determine outcome. Furthermore, these statistics depend strongly on the type of patients selected.
There are many reasons why pregnancy may not occur following IVF and embryo transfer, including
- The timing of ovulation may be misjudged, or ovulation may not be able to be predicted or may not occur
- Attempts to obtain eggs that develop during the monitored cycle may be unsuccessful
- The eggs obtained may be abnormal or may have been damaged during the retrieval process
- A semen specimen may not be able to be provided
- Fertilization of eggs to form embryos may not occur
- Cleavage or cell division of the fertilised eggs may not take place
- The embryo may not develop normally
- Implantation may not occur
- Equipment failure, infection and/or human error or other unforeseen and uncontrollable factors, which may result in the loss of or damage to the eggs, the semen sample and/or the embryos[6]
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.
Complications
The major complication of IVF is the risk of multiple births.[8] 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. Recent evidence suggest that singleton offspring after IVF is at higher risk for lower birth weight for unknown reasons.
Another risk of ovarian stimulation is the development of ovarian hyperstimulation syndrome.
If the underlying infertility is related to abnormalities in spermatogenesis, it is plausible, but too early to examine that male offspring is at higher risk for sperm abnormalities.
Birth defects
The issue of birth defects remains a controversial topic in IVF. A majority of studies do not show a significant increase after use of IVF. Some studies suggest higher rates for ICSI , while others do not support this finding.[7] Major birth defect include chromosomal abnormalities, genetic imprinting defects, and multiple organ abnormalities. Hansen et al conducted a systematic review of published studies (including ICSI) and found a 30-40% increase risk of birth defects associated with assisted reproductive technology when compared to children born after spontaneous conception.[8] Possible explanations offered were the underlying cause of the infertility, factors associated with IVF/ICSI, culture conditions, and medications, however, the actual cause is not known.
Cryopreservation
Embryo cryopreservation
If multiple embryos are generated, patients may choose to freeze embryos that are not transferred. Those embryos are placed in liquid nitrogen and can be preserved for a long time. There are currently 500,000 frozen embryos in the United States.[9] The advantage is that patients who fail to conceive may become pregnant using such embryos without having to go through a full IVF cycle. Or, if pregnancy occurred, they could return later for another pregnancy.
Oocyte cryopreservation
Cryopreservation of unfertilised mature oocytes has been successfully accomplished, e.g. in women who are likely to lose their ovarian reserve due to undergoing chemotherapy.[9]
Ovarian tissue cryopreservation
Cryopreservation of ovarian tissue is of interest to women who want to preserve their reproductive function beyond the natural limit, or whose reproductive potential is threatened by cancer therapy. Research on this issue is promising.
Adjunctive interventions
There are several variations or improvements of IVF, such as ICSI, ZIFT, GIFT and PGD. An increasing number of fertility specialists and centers offer acupuncture as a part of their IVF protocol, or maintain a list of acupuncturists specialising in infertility.
ICSI
Intracytoplasmic sperm injection (ICSI) is a more recent development associated with IVF which allows the sperm to be directly injected in to the egg using micromanipulation. This is used for sperm that have difficulty penetrating the egg and when sperm numbers are very low. ICSI results in success rates equal to IVF fertilisation.
ZIFT
In Zygote intrafallopian transfer (ZIFT) eggs are removed from the woman, fertilized and then placed in the woman's fallopian tubes rather than the uterus.
GIFT
In gamete intrafallopian transfer (GIFT) eggs are removed from the woman, and placed in one of the fallopian tubes, along with the man's sperm. This allows fertilization to take place inside the woman's body. Therefore, this variation is actually an in vivo fertilisation, and not an in vitro fertilisation.
PGD
PGD can be performed on embryos prior to the embryo transfer. A similar, but more general test has been developed called Preimplantation Genetic Haplotyping (PGH).
Acupuncture
An increasing number of fertility specialists and centers recognize the benefits of acupuncture and offer acupuncture as a part of their IVF protocol. Limited but supportive[10] evidence from clinical trials and case series suggests that acupuncture may improve the success rate of IVF and the quality of life[10] of patients undergoing IVF and that it is a safe[10] adjunct therapy.
Mechanism of acupuncture
Scientific literature lists four[10] mechanisms of how acupuncture can improve IVF outcomes ; these include
- Neuroendicrinological modulations
- Increased blood flow to uterus and ovaries
- Modulation in cytokines
- Reducing stress, anxiety and depression
Studies
Summarizing four acupuncture trials published in peer reviewed scientific journal Fertility and sterility, involving a total of just under 800 women, the results clearly showed a pregnancy was twice as likely to occur in the acupuncture group compared to the control group[10]. Many fertility specialists recognize the positive role of acupuncture, although there are some methodological issues to be taken into account when assessing non-pharmacological studies, furthermore there are issues when assessing effectiveness of acupuncture, as the treatment is performed in person and is very difficult to fake acupuncture. Even the fake needles used in acupuncture trials as a placebo are considered to be able to produce a therapeutic effect through acupressure, making the research even more difficult.
Following are examples of individual studies.
According to a report published in Fertility and Sterility, if done correctly, Acupuncture significantly improves IVF success rate[11].
Researchers in Adelaide has evaluated the effect of acupuncture on women undergoing IVF, and couldn't exclude a smaller treatment effect. However, there was no (statistically) significant difference compared to a control group of women not getting acupuncture[11]
A randomized, prospective study [12] showed that acupuncture significantly (p<0.01) increased IVF implantation rates and pregnancy rates. Positive trends were also observed in miscarriage rates although the results were not statistically significant. The study has been criticized by one scientist for lacking traditional scientific practices when interpreting the data [12], and by another scientist that positive impact of acupuncture on IVF success rates is not definitive. [13]. However, assessments of nonpharmacological treatments must take into consideration additional methodological issues. This criticism is possibly arising from lack of understanding of methodological differences in clinical trials evaluating nonpharmacological and pharmacological treatments[14] and in particular methodological issues in trials of acupuncture [15].
Electro-acupuncture in oocyte retrieval for IVF
Electro-acupuncture has a proven analgesic effect in oocyte retrieval for IVF.
Complementary medicines
Infertility patients commonly use complementary medicines. Health-care practitioners and fertility specialists need to be proactive in acquiring and documenting the use of these practices. There is a need to provide further information to patients on the use of CMs and therapies. Further research examining the reasons for use of CMs and therapies is needed.[13]
Hypnosis
A study of hypnotherapy suggests a higher success rate when integrated with treatment [14]. However, this study is not without criticism. Experts say the study failed to take into account key differences between the groups compared in the study. These differences would have had a major influence on their chances of conceiving [16].
Ethics
Issues
Certain ethical issues have been raised from the beginning when IVF was introduced. These concerns include:
- Bypassing the natural method of conception.
- The creation of life in the laboratory.
- Fertilization of more embryos than will be needed.
- Discarding of excess embryos.
- Unnatural environment for embryos.
- Use of untested technology.
- Not affordable for many.
- Misallocation of medical resources.
- Creation of embryos, then freezing them, and keeping them "in limbo".
- Exposure of embryos to unnatural substances.
- Destruction of embryos in research.
- Potential to create embryos for medical purposes.
- Potential to select embryos (PGD).
- Potential to modify embryos.
- Facilitation of the idea that embryos are commodities.
- Financial rewards for IVF doctors dissuade them from recommending other methods to couples.
- Infertility is treated as a disease and not as a symptom of underlying medical problems.
- The long term effect on frozen embryos is unknown.
Separating the traditional mother-father model
The IVF process requires sperm, eggs, a uterus and a bed. To achieve a pregnancy any of these requirements can be provided by a third person. (a threesome): third party reproduction. This has created additional ethical and legal concerns. The use of IVF provides also greater range of options for single people and same-sex couples wishing to have children. Although both groups already raise children, IVF facilitates this process. Some people object that this could give psychological problems to the child if they grow up without a mother/father.
A number of cases have achieved notoriety:
- In 2001, a French woman received worldwide publicity when she posed as the wife of her brother in order to give birth to a donor egg fertilized by his sperm. Some saw this as a form of incest; others thought it would prove psychologically unhealthy for the child when he learned how he was delivered; whereas other people simply couldn't see anything wrong with the situation.
- In a few cases laboratory mix-ups (misidentified gametes, transfer of wrong embryos) have occurred leading to legal action against the IVF provider and complex paternity suits. An example is the case of a woman in California who received the embryo of another couple and was notified of this mistake after the birth of her son.[17]
Pregnancy past menopause
While menopause has set a natural barrier to further conception, IVF has allowed women to be pregnant in their fifties and sixties. Women whose uteruses have been appropriately prepared receive embryos that originated from an egg of an egg donor. Therefore, although these women do not have a genetic link with the child, they have an emotional link through pregnancy and childbirth. In many cases the genetic father of the child is the woman's partner. Even after menopause the uterus is fully capable to carry out its function.[18]
Religious objections
The Roman Catholic Church is opposed to most kinds of in vitro fertilization (although GIFT is accepted because fertilization takes place inside the body and not inside a Petri dish) and advocates that infertility is a call from God to adopt children. According to the Catholic Church, it "infringe[s] the child's right to be born of a father and mother known to him and bound to each other by marriage."[19] Also, embryos are discarded in the process, causing them to die. Catholics and many people of other faiths or none see embryos as human lives with the same rights as all others and, therefore, view this procedure as unacceptable.
Regulatory events
While in the United States IVF programs operate under voluntary guidelines, programs in many other countries are subject to regulations that regulate many aspects of IVF practice. In such settings regulations may dictate:
- The number of oocytes that can be fertilized.
- The number of embryos that can be transferred.
- The use of cryopreservation.
- The use of third party reproduction.
- The ability to perform tests or interventions on the embryo.
In 2004, the government of Italy made it a crime to freeze human embryos or to perform preimplantation diagnosis.
References
- ↑ The spelling fertilisation is a British variant of fertilization. The spelling fertilization is used in American and Canadian English, and often in academic British English.
- ↑ Steptoe PC, Edwards RG (1978). "Birth after the reimplantation of a human embryo". Lancet. 2 (8085): 366. PMID 79723.
- ↑ Cohen J, Trounson A, Dawson K, Jones H, Hazekamp J, Nygren KG, Hamberger L. (2005). "The early days of IVF outside the UK". Hum Reprod Update: 439–59. PMID 15923202.
- ↑ Cohen LEETON, John (2004). "The early history of IVF in Australia and its contribution to the world (1970-1990)". The Australian and New Zealand Journal of Obstetrics and Gynaecology. 44 (6): 495–501.
- ↑ Papanikolaou EG, Camus M, Kolibianakis EM, Van Landuyt L, Van Steirteghem A, Devroey P (2006). "In Vitro Fertilization with Single Blastocyst-Stage versus Single Cleavage-Stage Embryos". N Engl J Med. 354: 1139. PMID 16540614.
- ↑ Abington Reproductive Medicine, In Vitro Fertilization (IVF): Why Pregnancy May Not Occur. (2006)
- ↑ Kurinczuk JJ (2003). "Safety issues in assisted reproduction technology. From theory to reality--just what are the data telling us about ICSI offspring health and future fertility and should we be concerned?". Hum Reprod. 18 (5): 925–31. PMID 12721163.
- ↑ Hansen M, Bower C, Milne E, de Klerk N, Kurinczuk JJ (2005). "Assisted reproductive technologies and the risk of birth defects--a systematic review". Hum Reprod. 20 (2): 328–38. PMID 15567881.
- ↑ Porcu E, Fabbri R, Damiano G, Fratto R, Giunchi S, Venturoli S (2004). "Oocyte cryopreservation in oncological patients". Eur J Obstet Gynecol Reprod Biol. 113 Suppl 1: S14–6. PMID 15041124.
- ↑ 10.0 10.1 10.2 10.3 [1] Anderson BJ, Haimovici F, Ginsburg ES, Schust DJ, Wayne PM. Pacific College of Oriental Medicine, New York, USA.
- ↑ [2] Influence of acupuncture stimulation on pregnancy rates for women undergoing embryo transfer. Smith C, Coyle M, Norman RJ. School of Health Science, The University of South Australia, South Australia, Australia. caroline.smith@acnhw.com.au
- ↑ [3] Collins J. Department of Obstetrics and Gynecology, McMaster University, Hamilton, Ontario, Canada. collinsj@auracom.com
- ↑ Domar AD. Domar Center for Complementary Healthcare, Boston IVF, Massachusetts, USA. Domar@domarcenter.com
- ↑ Methodological Differences in Clinical Trials Evaluating Nonpharmacological and Pharmacological Treatments of Hip and Knee Osteoarthritis Isabelle Boutron, MD; Florence Tubach, MD; Bruno Giraudeau, PhD; Philippe Ravaud, MD, PhD JAMA. 2003;290:1062-1070
- ↑ Methodological Issues in Trials of Acupuncture Kaptchuk et al. JAMA.2001; 285: 1015-1016.
- ↑ BBC Hypnosis 'doubles IVF success'
- ↑ Ayers C (2004). "Mother wins $1m for IVF mix-up but may lose son". Timesonline. [4]. Text " volume " ignored (help); Text " issue " ignored (help); Text " pages " ignored (help)
- ↑ Parks, Jennifer A. (1996). "A closer look at reproductive technology and postmenopausal motherhood". CMAJ. 154 (8): 1189–91. PMID 8612255.
- ↑ Catechism of the Catholic Church section 2376
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