In vitro fertilisation

In Vitro Fertilization

Definition

In vitro fertilization (IVF) is a procedure in which eggs (ova) from a woman's ovary are removed. They are fertilized with sperm in a laboratory procedure, and then the fertilized egg (embryo) is returned to the woman's uterus.

Purpose

IVF is one of several assisted reproductive techniques (ART) used to help infertile couples to conceive a child. If after one year of having sexual intercourse without the use of birth control a woman is unable to get pregnant, infertility is suspected. Some of the reasons for infertility are damaged or blocked fallopian tubes, hormonal imbalance, or endometriosis in the woman. In the man, low sperm count or poor quality sperm can cause infertility.

IVF is one of several possible methods to increase the chance for an infertile couple to become pregnant. Its use depends on the reason for infertility. IVF may be an option if there is a blockage in the fallopian tube or endometriosis in the woman or low sperm count or poor quality sperm in the man. There are other possible treatments for these conditions, such as surgery for blocked tubes or endometriosis, which may be tried before IVF.

IVF will not work for a woman who is not capable of ovulating or a man who is not able to produce at least a few healthy sperm.

Precautions

The screening procedures and treatments for infertility can become a long, expensive, and sometimes, disappointing process. Each IVF attempt takes at least an entire menstrual cycle and can cost $5,000-$10,000, which may or may not be covered by health insurance. The anxiety of dealing with infertility can challenge both individuals and their relationship. The added stress and expense of multiple clinic visits, testing, treatments, and surgical procedures can become overwhelming. Couples may want to receive counseling and support throughout the process.

Description

In vitro fertilization is a procedure where the joining of egg and sperm takes place outside of the woman's body. A woman may be given fertility drugs before this procedure so that several eggs mature in the ovaries at the same time. Eggs (ova) are removed from a woman's ovaries using a long, thin needle. The physician gains access to the ovaries using one of two possible procedures. One procedure involves inserting the needle through the vagina (transvaginally). The physician guides the needle to the location of the ovaries with the help of an ultrasound machine. In the other procedure, called laparoscopy, a small thin tube with a viewing lens is inserted through an incision in the navel. This allows the physician to see inside the patient, and locate the ovaries, on a video monitor.

Once the eggs are removed, they are mixed with sperm in a laboratory dish or test tube. (This is where the term test tube baby comes from.) The eggs are monitored for several days. Once there is evidence that fertilization has occurred and the cells begin to divide, they are then returned to the woman's uterus.

In the procedure to remove eggs, enough may be gathered to be frozen and saved (either fertilized or unfertilized) for additional IVF attempts. A 2004 study from the Mayo Clinic found that frozen sperm was as effective as fresh sperm for IVF.

IVF has been used successfully since 1978, when the first child to be conceived by this method was born in England. Over the past 20 years, thousands of couples have used this method of ART or similar procedures to conceive.

Other types of assisted reproductive technologies might be used to achieve pregnancy. A procedure called intracytoplasmic sperm injection (ICSI) uses a manipulation technique that must be performed using a microscope to inject a single sperm into each egg. The fertilized eggs can then be returned to the uterus, as in IVF. In gamete intrafallopian tube transfer (GIFT) the eggs and sperm are mixed in a narrow tube and then deposited in the fallopian tube, where fertilization normally takes place. Another variation on IVF is zygote intrafallopian tube transfer (ZIFT). As in IVF, the fertilization of the eggs occurs in a laboratory dish. And, similar to GIFT, the embryos are placed in the fallopian tube (rather than the uterus as with IVF).

Preparation

Once a woman is determined to be a good candidate for in vitro fertilization, she will generally be given "fertility drugs" to stimulate ovulation and the development of multiple eggs. These drugs may include gonadotropin releasing hormone agonists (GnRHa), Pergonal, Clomid, or human chorionic gonadotropin (hcg). The maturation of the eggs is then monitored with ultrasound tests and frequent blood tests. If enough eggs mature, the physician will perform the procedure to remove them. The woman may be given a sedative prior to the procedure. A local anesthetic agent may also be used to reduce discomfort during the procedure.

Aftercare

After the IVF procedure is performed the woman can resume normal activities. A pregnancy test can be done approximately 12-14 days later to determine if the procedure was successful.

Risks

The risks associated with in vitro fertilization include the possibility of multiple pregnancy (since several embryos may be implanted) and ectopic pregnancy (an embryo that implants in the fallopian tube or in the abdominal cavity outside the uterus). There is a slight risk of ovarian rupture, bleeding, infections, and complications of anesthesia. If the procedure is successful and pregnancy is achieved, the pregnancy would carry the same risks as any pregnancy achieved without assisted technology.

Normal results

Success rates vary widely between clinics and between physicians performing the procedure and implantation does not guarantee pregnancy. Therefore, the procedure may have to be repeated more than once to achieve pregnancy. However, success rates have improved in recent years, up from 20% in 1995 to 27% in 2001.

Abnormal results

An ectopic or multiple pregnancy may abort spontaneously or may require termination if the health of the mother is at risk. The number of multiple pregnancies has decreased in recent years as technical advances and professional guidelines have led to implanting of fewer embryos per attempt.

Resources

Periodicals

"Frozen, Fresh Sperm Both Effective for In Vitro Fertilization." Obesity, Fitness & Wellness Week June 5, 2004: 1059.

"Multiple Births Via In Vitro Fertilization Are Declining." Women's Health Weekly May 6, 2004: 16.

Organizations

American Society for Reproductive Medicine. 1209 Montgomery Highway, Birmingham, AL 35216-2809. (205) 978-5000. 〈asrm@asrm.com〉 http://www.asrm.com.

Center for Fertility and In Vitro Fertilization Loma Linda University. 11370 Anderson St., Loma Linda, CA 92354. (909) 796-4851. http://www.llu.edu/llumc/fertility.

Resolve. 1310 Broadway, Somerville, MA 02144-1731. (617) 623-0744. http://www.resolve.org.

Other

"Infertility." HealthWorld Online Page. http://www.healthy.net.

"In vitro Fertilization: A Teacher's Guide from Newton's Apple." PBS Page. http://www.pbs.org/ktca/newtons/11/invitro.html.

fertilization /fer·ti·li·za·tion/ (fer″tĭ-lĭ-za´shun) impregnation; union of male and female gametes to form the diploid zygote, leading to development of a new individual.

external fertilization union of the gametes outside the bodies of the originating organisms, as in most fish.

internal fertilization union of the gametes inside the body of the female, the sperm having been transferred from the body of the male by an accessory sex organ or other means.

in vitro fertilization removal of a secondary oocyte, fertilization of it in a culture medium in the laboratory, and placement of the dividing zygote into the uterus.

in vitro fertilization

n. Abbr. IVF

Fertilization of an egg outside the body of a female by the addition of sperm, as a means of producing a zygote.

in vitro fertilization (IVF),

a method of fertilizing human ova outside the body by collecting the mature ova and placing them in a dish with a sample of spermatozoa. After an incubation period of 48 to 72 hours, the fertilized ova are injected into the uterus through the cervix. The procedure takes from 2 to 3 days. See also gamete intrafallopian transfer.

fertilization [fer″tĭ-lĭ-za´shun]

in human reproduction, the process by which the male's sperm unites with the female's oocyte, creating a new life. The sex and other biologic traits of the new individual are determined by the combined genes and chromosomes that exist in the sperm and oocyte. See also conception and reproduction. Called also fecundation and impregnation.

After injection into the vagina, millions of sperm cells (spermatozoa) make use of their whiplike tails to swim through the cervix toward the uterus. Most are destroyed along the way by secretions in the vagina, but some reach the uterus and a few may enter the fallopian tubes. A very small number may survive as long as 48 hours. If during this period only one sperm succeeds in entering a fallopian tube and meeting there an oocyte ready to be fertilized, conception can occur. This event is possible only during a period of about 4 days of the month. After the sperm lodges in the oocyte, the tail disappears, but the head unites with the oocyte to form the zygote.

in vitro fertilization the process by which conception takes place in a laboratory medium; the term literally means fertilization “in glass.” A lay term for the product of in vitro fertilization is “test tube baby.”

The treatment cycle involves the following steps: (1) Induction of ovulation with fertility drugs, such as clomiphene citrate, injectable follicle-stimulating hormone/luteinizing hormone, or both, to produce multiple ovarian follicles. When the largest follicle reaches 20 mm in diameter the patient is given an injection of human chorionic gonadotropin to induce expulsion of the oocyte from the follicle. (2) Laparoscopy and follicular aspiration for the harvesting of oocytes. (3) Maturation of retrieved oocytes and inoculation with the husband's or donor's sperm. (4) Incubation of the resulting embryos until they reach the two- to six-cell stage. (5) Transfer of an embryo via catheter into the patient's uterus; at this point intensive intervention ceases, the pregnancy is considered normal, and no further manipulation is required.

in vivo fertilization union of the sperm and ovum within the reproductive tract of the female; usually taken to mean artificial insemination in which the sperm is artificially introduced into the vagina, cervix, or uterine cavity to overcome the problem of infertility.

fertilization

in animal reproduction, the process by which the spermatozoon unites with the ovum. By this event, also called conception, the male and female gametes unite to form a single-celled zygote. When one spermatozoon penetrates the ovum a reaction occurs which prevents any further spermatozoa entering. The nuclei of the spermatozoon and the ovum fuse in a process called syngamy and fertilization is complete.

Spermatozoa lodged in the female reproductive tract maintain their fertility for 5 days in mares, up to 90 hours in bitches and for 24 to 48 hours in cow, ewe, sow. In the female, the ovulated ovum remains viable in the tract for 12 to 18 hours.

Fertilization. By permission from Aspinall V, O'Reilly M, Introduction to Veterinary Anatomy and Physiology, Butterworth Heinemann, 2004

in vitro fertilization

union of male and female germ cells outside the body, in an artificial environment.