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Artificial insemination is the name for the procedure of placing sperm (or semen) in the reproductive tract of a female by means other than sexual intercourse (or NI) with the intention of impregnating the female.

Specifically, freshly ejaculated sperm, or sperm which has been frozen and thawed, is placed in the cervix (intracervical insemination) (ICI)) or, after washing, into the female's uterus (intrauterine insemination) (IUI) by artificial means.

Modern techniques for human artificial insemination were first developed for the dairy cattle industry to allow many cows to be impregnated with the sperm of a bull with traits for improved milk production.

In humans, artificial insemination was origianlly developed as a means of helping couples to conceive where there were 'male factor' problems of a physical or pschycological nature affecting the male partner which prevented or impeeded conception. Today, the process is more commonly used where a woman has no male partner and the sperm is provided by or on behalf of a sperm donor. In cases where donor sperm is used the woman is the gestational and genetic mother of the child produced, and the sperm donor is the genetic or biological father of the child.


In Humans

Preparations

A sperm sample will be provided by the male partner of the woman undergoing artificial insemination, but sperm provided through sperm donation by a sperm donor may be used if, for example, the woman's partner produces too few motile sperm, if he carries a genetic disorder, or if the woman has no male partner. Sperm is usually obtained through masturbation or the use of an electrical stimulator, although a special condom, known as a collection condom, may be used to collect the semen during intercourse.

The man providing the sperm is usually advised not to ejaculate for two to three days before providing the sample in order to increase the sperm count.

A woman's menstrual cycle is closely observed, by tracking basal body temperature (BBT) and changes in vaginal mucus, or using ovulation kits, ultrasounds or blood tests.

When using intrauterine insemination (IUI), the sperm must have been “washed” in a laboratory and concentrated in Hams F10 media without L-glutamine, warmed to 37C.[1] The process of “washing” the sperm increases the chances of fertilization and removes any mucus and non-motile sperm in the semen. Pre and post concentration of motile sperm is counted.

If sperm is provided by a sperm donor through a sperm bank, it will be frozen and quarantined for a particular period and the donor will be tested before and after production of the sample to ensure that he does not carry a transmissible disease. Sperm samples donated in this way are produced through masturbation by the sperm donor at the sperm bank. A chemical known as a cryoprotectant is added to the sperm to aid the freezing and thawing process. Further chemicals may be added which separate the most active sperm in the sample as well as extending or diluting the sample so that vials for a number of inseminations are produced. For fresh shipping, a semen extender is used.

Procedure

When an ovum is released, semen provided by the woman's male partner, or by a sperm donor is inserted into the woman's vagina or uterus. The semen may be fresh or it may be frozen semen which has been thawed. Where donor sperm is supplied by a sperm bank, it will always be quarantined and frozen and will need to be thawed before use. In the case of vaginal artificial insemination, semen is usually placed in the vagina by way of a needleless syringe. A longer tube, known as a 'tom cat' may be attached to the end of the syringe to facilitate deposit of the semen deeper into the vagina. The woman is generally advised to lie still for a half hour or so after the insemination to prevent seepage and to allow fertilization to take place. An alternative method involves the placing of partner or donor sperm in the woman's vagina by means of a specially designed cervical cap, a conception device, which holds the semen in place for a period of time, usually for several hours, to allow fertilization to take place. Using this method, a woman may go about her usual activities while the cervical cap holds the semen in the vagina. A more efficient method of artificial insemination is to insert semen directly into the woman's uterus. Where this method is employed only 'washed' semen may be used and this is inserted by means of a catheter. Specially designed equipment is available for carrying out artificial inseminations. Semen is occasionally inserted twice within a 'treatment cycle'. If the procedure is successful, the woman will conceive and carry to term a baby. A pregnancy resulting from artificial insemination will be no different from a pregnancy achieved by sexual intercourse. However, there may be a slight increased likelihood of multiple births if drugs are used by the woman for a 'stimulated' cycle.

Donor variations

Either sperm provided by the woman's husband or partner (artificial insemination by husband, AIH) or sperm provided by a known or anonymous sperm donor (artificial insemination by donor, AID or DI) can be used.

Techniques

The main techniques used are:

  • Intracervical insemination (ICI), the easiest way to inseminate, where semen is injected high into the cervix with a needle-less syringe
  • Intrauterine insemination (IUI), where sperm is injected directly into a woman's uterus

Insemination may also be performed into the Fallopian tube although this procedure is no longer generally regarded as having any beneficial effect compared with IUI.[2]

See also in vitro fertilisation (IVF) techniques which may involve the use of partner or donor sperm.

Intracervical insemination

ICI is the easiest way to inseminate, where semen is injected high into the cervix with a needle-less syringe. This process most closely replicates the way in which semen is deposited by the penis in the cervix or fornix when the male ejaculates during vaginal intercourse. It is the simplest method of artificial insemination and 'unwashed' or raw semen may be used. It is probably therefore, the most popular method and is used in most home, self and practitioner inseminations. However, more technical procedures may be used which increase the chances of conception. When performed at home without the presence of a professional this procedure is sometimes referred to as intravaginal insemination or IVI.[3]

Intrauterine insemination

'Washed sperm', that is, spermatozoa which have been removed from most other components of the seminal fluids, can be injected directly into a woman's uterus in a process called intrauterine insemination (IUI). If the semen is not washed it may elicit uterine cramping, expelling the semen and causing pain, due to content of prostaglandins. (Prostaglandins are also the compounds responsible for causing the myometrium to contract and expel the menses from the uterus, during menstruation.) The woman should rest on the table for 15 minutes after an IUI to optimize the pregnancy rate.[4]

To have optimal chances with IUI, the female should be under 30 years of age, and the man should have a TMS of more than 5 million per ml.[5] In practice, donor sperm will satisfy these criteria. A promising cycle is one that offers two follicles measuring more than 16 mm, and estrogen of more than 500 pg/mL on the day of hCG administration.[5]

Intratubal insemination

IUI can furthermore be combined with intratubal insemination (ITI), into the Fallopian tube although this procedure is no longer generally regarded as having any beneficial effect compared with IUI.[2] ITI however, should not be confused with gamete intrafallopian transfer, where both eggs and sperm are mixed outside the woman's body and then immediately inserted into the Fallopian tube where fertilization takes place.

Pregnancy rate

Success rates, or pregnancy rates for artificial insemination may be very misleading, since many factors including the age and health of the recipient have to be included to give a meaningful answer, e.g. definition of success and calculation of the total population.[6] For couples whose infertility is unexplained, unstimulated IUI is no more effective than natural means of conception.[7][8]

File:Success rates by amount of sperm.svg

Generally, it is 10 to 15% per menstrual cycle using ICI, and[9] and 15-20% per cycle for IUI.[9] In IUI, about 60 to 70% have achieved pregnancy after 6 cycles.[10]

As seen on graph, pregnancy rate also depends on the total sperm count, or, more specifically, the total motile sperm count (TMSC), used in a cycle. It increases with increasing TMSC, but only up to a certain count, when other factors become limiting to success. The summed pregnancy rate of two cycles using a TMSC of 5 million (may be a TSC of ~10 million on graph) in each cycle is substantially higher than one single cycle using a TMSC of 10 million. However, although more cost-efficient, using a lower TMSC also increases the average time taken before getting pregnant. Women whose age is becoming a major factor in fertility may not want to spend that extra time.

Samples per child

How many samples (ejaculates) that are required give rise to a child varies substantially from person to person, as well as from clinic to clinic.

However, the following equations generalize the main factors involved:

For intracervical insemination:

N = \frac{V_s \times c \times r_s}{n_r}
  • N is how many children a single sample can give rise to.
  • Vs is the volume of a sample (ejaculate), usually between 1.0 mL and 6.5 mL[11]
  • c is the concentration of motile sperm in a sample after freezing and thawing, approximately 5-20 million per ml but varies substantially
  • rs is the pregnancy rate per cycle, approximately 10% to 15%[9]
  • nr is the total motile sperm count recommended for use in a cycle, approximately 20 million.[12] The pregnancy rate increases with increasing number of motile sperm used, but only up to a certain degree, when other factors become limiting instead.


File:Live birth rates by TMSC.svg

With these numbers, one sample would on average help giving rise to 0.1-0.6 children, that is, it actually takes on average 2-5 samples to make a child.

For intrauterine insemination (IUI), a centrifugation fraction (fc) may be added to the equation:

fc is the fraction of the volume that remains after centrifugation of the sample, which may be about half (0.5) to a third (0.33).
N = \frac{V_s \times f_c \times c \times r_s}{n_r}

On the other hand, only 5 million motile sperm may be needed per cycle with IUI (nr=5 million)[12]

Thus, only 1-3 samples may be needed for a child if used for IUI.

Artificial insemination in livestock and pets

File:Horse breeding dummy.jpg

Artificial insemination is used in animals to propagate desirable characteristics of one male to many females or overcome breeding problems, particularly in the cases of sheep, horses, cattle, pigs, pedigree dogs, and honeybees. Semen is collected, extended, then cooled or frozen. It can be used on site or shipped to the female's location. If frozen, the small plastic tube holding the semen is referred to as a "straw". To allow the sperm to remain viable during the time before and after it is frozen, the semen is mixed with a solution containing glycerol or other cryoprotectants. An "extender" is a solution that allows the semen from a donor to impregnate more females by making insemination possible with fewer sperm. Antibiotics, such as streptomycin, are sometimes added to the sperm to control some bacterial venereal diseases. Before the actual insemination, estrus may be induced through the use of progestogen and another hormone (usually PMSG).

Artificial insemination of farm animals is very common in today's agriculture industry in the developed world, especially for breeding dairy cattle (75% of all inseminations) and swine (up to 85% of all inseminations). It provides an economical means for a livestock breeder to improve their herds utilizing males having very desirable traits.

Although common with cattle and swine, AI is not as widely practised in the breeding of horses. A small number of equine associations in North America only accept horses that have been conceived by "natural cover" the actual physical mating of a mare to a stallion. The Jockey Club being the most notable of these - no AI is allowed in Thoroughbred breeding.[13] Other registries such as the AQHA and warmblood registries allow registration of foals created through AI, and the process is widely used allowing the breeding of mares to stallions not resident at the same facility - or even in the same country - through the use of transported frozen or cooled semen.

See also

Notes

  1. Adams, Robert, M.D."invitro fertilization technique", Monterey, CA, 1988
  2. 2.0 2.1 Hurd WW, Randolph JF Jr, Ansbacher R, Menge AC, Ohl DA, Brown AN.. Comparison of intracervical, intrauterine, and intratubal techniques for donor insemination..
  3. European Sperm Bank USA
  4. Laurie Barclay. Immobilization May Improve Pregnancy Rate After Intrauterine Insemination.
  5. 5.0 5.1 Merviel P, Heraud MH, Grenier N, Lourdel E, Sanguinet P, Copin H (November 2008). Predictive factors for pregnancy after intrauterine insemination (IUI): An analysis of 1038 cycles and a review of the literature. Fertil. Steril..
  6. IVF.com
  7. Fertility treatments 'no benefit'. BBC News, 7 August 2008
  8. Research paper. British Medical Journal, 7 August 2008
  9. 9.0 9.1 9.2 Utrecht CS News Subject: Infertility FAQ (part 4/4)
  10. Intrauterine insemination. Information notes from the fertility clinic at Aarhus University Hospital, Skejby. By PhD Ulrik Kesmodel et al.
  11. Essig, Maria G., Edited by Susan Van Houten and Tracy Landauer, Reviewed by Martin Gabica and Avery L. Seifert Semen Analysis. Healthwise. WebMD. URL accessed on 2007-08-05.
  12. 12.0 12.1 Cryos FAQs - What is the recommended quantity and quality by ordering of donor semen?
  13. The Jockey Club has never allowed artificial insemination.

References

  • Hammond, John, et al., The Artificial Insemination of Cattle (Cambridge, Heffer, 1947, 61pp)

External links

Template:Pregnancy Template:Assisted reproductive technology


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