Home > Encyclopedia of Nursing & Allied Health > Infertility

Definition

Infertility is the failure to conceive a pregnancy after attempting for at least one full year. In primary infertility, pregnancy has never occurred. In secondary infertility, one or both members of the couple have previously conceived, but are unable to conceive again after a full year of attempting.

Description

Currently, in the United States, about one in five couples struggles with infertility at any given time. Infertility has increased as a problem over the last 30 years. Some studies assign the blame for this increase on social phenomena, including the tendency for marriage to occur at a later age. Fertility in women decreases with increasing age, as illustrated by the following statistics. In one year of trying to become pregnant:

• Infertility in women at age 20 is 4%.
• Infertility in women at age 30 is 7%.
• Infertility in women at age 35 is 12%.
• Infertility in women over the age of 40 is 75%.

Many individuals have multiple sexual partners before marriage. This increase in numbers of sexual partners has led to a rise in sexually transmitted diseases. Scarring from these infections, especially from pelvic inflammatory disease (PID, a serious infection of the female reproductive organs, most commonly caused by chlamydia and gonorrhea), seems to be partially responsible for increases in infertility. Furthermore, use of some forms of a contraceptive called the intrauterine device (IUD) contributed to an increased rate of pelvic inflammatory disease. However, the newer IUDs do not cause infections.

To understand issues of infertility, it is first necessary to understand the basics of human reproduction. Fertilization occurs when a sperm from the male merges with an egg (ovum) from the female, creating a zygote that contains genetic material (DNA) from both the father and the mother. If pregnancy is then established, the zygote will develop into an embryo, then a fetus, and ultimately a baby will be born.

The male contribution to fertilization and the establishment of pregnancy is the sperm. Sperm are small cells that carry the father's genetic material, which is contained within the oval head of the sperm. The sperm are mixed into a fluid called semen that is discharged from the penis during sexual intercourse. The whip-like tail of sperm allows them to swim up the female reproductive tract in search of an egg (ovum).

The female makes many contributions to fertilization and the establishment of pregnancy. The ovum is the cell that carries the mother's genetic material; ova (plural of ovum) develop within the ovaries. Once a month, a single mature ovum is produced, and leaves the ovary in a process called ovulation. This ovum enters a tube leading to the uterus (the fallopian tube). If fertilization is to occur, the ovum must encounter the sperm in the fallopian tube.

When fertilization occurs, the resulting cell is called a zygote. This single cell will multiply within the fallopian tube, and the resulting cluster of cells, a blastocyst, will then move into the womb (uterus). The uterine lining (endometrium) has been preparing itself to receive a pregnancy by growing thicker. If the blastocyst successfully reaches the inside of the uterus and attaches itself to the wall of the uterus, then pregnancy has been achieved.

Causes and symptoms

Unlike most medical problems, infertility is an issue requiring the careful evaluation of two separate individuals, as well as an evaluation of their interactions with each other. In about 3–4% of couples, no cause for their infertility will be discovered.

The main factors involved in causing infertility, ranging from the most to the least common, include:

• male problems: 30-40%
• ovulation problems: 10-15%
• pelvic disease: 30-40%
• cervical factors: 10-15%
• undiagnosed: 5-10%

Diagnosis

Diagnosis of infertility involves examination of both male and female partners.

Male factors

Male infertility can be caused by a number of different characteristics of sperm. To check for these characteristics, a sample of semen is obtained and examined under a microscope (semen analysis). Four basic characteristics are usually evaluated:

• Sperm count refers to the number of sperm present in a semen sample. The typical number of sperm present in just one milliliter (ml) of semen is more than 20 million. A male with only 5–20 million sperm per ml of semen is considered subfertile, while a male with less than 5 million sperm per ml of semen is considered to be infertile.
• Sperm are examined to determine how well they swim (sperm motility) and to ensure that most have normal structure (morphology). Not all sperm within a specimen of semen will be perfectly normal. Some may be immature, and others may have abnormalities of the head or tail. A typical semen sample will contain no more than 25% abnormal forms of sperm.
• Volume of the semen sample is important; an abnormal amount of semen could adversely affect the ability of the sperm to successfully fertilize an ovum.
• The ability of the sperm to penetrate the outer coat of the ovum is also evaluated. This is accomplished by observing whether sperm in a semen sample can penetrate the outer coat of a hamster ovum. Fertilization cannot occur, of course, but this test is useful in predicting the ability of an individual's sperm to penetrate a human ovum.

Any number of conditions result in abnormal findings in the semen analysis. Men can be born with testicles that have not descended properly from the abdominal cavity into the scrotal sac, or may be born with only one testicle, instead of the normal two. Testicle size might be smaller than normal. Past infection (including mumps) can affect testicular function, as can a past injury. The presence of abnormally large veins (varicocele) in the testicles can increase testicular temperature, which decreases sperm count.

History of having been exposed to various toxins, drug use, excessive alcohol use, use of anabolic steroids, certain medications, diabetes, thyroid problems, or other endocrine disturbances can have direct effects on the formation of sperm (spermatogenesis). Problems with the male anatomy can cause sperm to be ejaculated into the bladder, or scarring from past infections can interfere with ejaculation.

Female factors

OVULATORY PROBLEMS. The first step in diagnosing ovulatory problems is to make sure that an ovum is being produced each month. A woman's body temperature in the morning is slightly higher around the time of ovulation. A woman can measure and record her temperatures daily, and a chart can be drawn to show whether or not ovulation has occurred. Luteinizing hormone (LH) is released just before ovulation. A simple urine test can be done to check if LH has been released around the time that ovulation is expected.

PELVIC ADHESIONS AND ENDOMETRIOSIS. Pelvic adhesions and endometriosis can cause infertility by preventing the sperm from reaching the egg or interfering with fertilization.

Pelvic adhesions are fibrous scars. These scars can be the result of past infections, such as pelvic inflammatory disease, or infections following abortions or prior births. Previous surgeries can also leave behind scarring. Pelvic adhesions cause infertility by blocking the fallopian tubes. The ovum may be prevented from traveling down the fallopian tube from the ovary or the sperm may be prevented from traveling up the fallopian tube from the uterus.

A hysterosalpingogram (HSG) can show if the fallopian tubes are blocked. This is an x-ray exam that tests whether dye material can travel through a woman's fallopian tubes. Scarring also can be diagnosed by examining the pelvic area through the use of a scope that can be inserted into the abdomen through a tiny incision made near the navel. This technique is called laparoscopy.

Endometriosis may lead to pelvic adhesions. Endometriosis is the abnormal location of uterine tissue outside of the uterus. When uterine tissue is implanted elsewhere in the pelvis, it still bleeds on a monthly basis with the start of the normal menstrual period. This leads to irritation within the pelvis around the site of this abnormal tissue and bleeding, and may cause scarring.

CERVICAL FACTORS. The cervix is the opening from the vagina into the uterus through which the sperm must pass. Mucus produced by the cervix helps to transport the sperm into the uterus. Cervical mucus can be examined under a microscope to diagnose whether cervical factors are contributing to infertility. An injury to the cervix or scarring of the cervix after surgery or infection can result in a smaller than normal cervical opening, which would make it difficult for sperm to enter. Injury or infection can also decrease the number of glands in the cervix, leading to a smaller amount of cervical mucus. In other situations, the mucus produced might be the wrong consistency to allow sperm to travel through. In addition, some women produce antibodies (immune cells) that identify sperm as foreign invaders and kill them. Finally, cervical stenosis is a rare cause of infertility.

Treatment

Treatment of infertility first involves addressing underlying conditions in the male and female partners. If these fail to produce a pregnancy, additional steps can be undertaken to assist pregnancy.

Treatment of male infertility includes first addressing known reversible factors such as discontinuing any medication known to have an effect on spermatogenesis or ejaculation, decreasing alcohol intake, or treating thyroid or other endocrine disease. Varicoceles can be treated surgically. Testosterone in low doses can improve sperm motility.

Other treatments of male infertility include collecting semen samples from multiple ejaculations, after which the semen is put through a process that allows the most motile sperm to be sorted out. These motile sperm are pooled together to create a concentrate that can be deposited into the female partner's uterus at ovulation. In cases where the male partner's sperm is proven unviable, with the consent of both partners, donor sperm may be used. Depositing the male partner's sperm or donor sperm by mechanical means into the female partner is a form of artificial insemination.

Treatment of ovulatory problems depends on the cause. If a thyroid or pituitary problem is responsible, treating that problem can restore fertility. Medication such as Clomid and Pergonal can be used to stimulate fertility. These drugs may increase the risk of multiple births (twins, triplets, etc.).

Pelvic adhesions can be excised with laparoscopy. Endometriosis can be treated with certain medications, but may also require surgery to repair any obstruction caused by adhesions.

Treatment of cervical factors includes antibiotics in the case of an infection, steroids to decrease production of anti-sperm antibodies, and artificial insemination techniques to completely bypass the cervical mucus.

Assisted reproductive techniques include in vitro fertilization (IVF), gamete intrafallopian transfer (GIFT), and zygote intrafallopian tube transfer (ZIFT). These are usually used after other techniques to treat infertility have failed.

IVF involves the use of a drug to induce the simultaneous release of many eggs from a female's ovaries. These are surgically retrieved. Meanwhile, several semen samples are obtained from the male partner, and a sperm concentrate is prepared. The ova and sperm are then combined in a laboratory, where several of the ova may be fertilized. Cell division is allowed to take place up to the embryo stage. While this takes place, the female may be given drugs to prepare her uterus to receive an embryo. Three or four of the embryos are transferred to the female's uterus, and the wait begins to see if any or all of them implant and result in an actual pregnancy.

Success rates of IVF are still rather low. Most centers report pregnancy rates between 10–20%. Since most IVF procedures put more than one embryo into the uterus, the chance for a multiple birth is greatly increased in couples undergoing IVF.

GIFT involves retrieval of both multiple ova and semen, and the mechanical placement of both within the female partner's fallopian tubes. ZIFT involves the same retrieval of ova and semen and the fertilization and growth in the laboratory up to the zygote stage, at which point the zygotes are placed in the fallopian tubes. Both GIFT and ZIFT have higher success rates than IVF.

Prognosis

It is very difficult to obtain statistics regarding the prognosis of infertility because many different problems may exist within an individual or couple trying to conceive. In general, of all couples who undergo a complete evaluation of infertility followed by treatment, about half will ultimately have a successful pregnancy. Of those couples who do not choose to undergo evaluation or treatment, about 5% will go on to conceive after a year or more of infertility.

Health care team roles

Gynecologists who specialize in infertility lead most investigations. Registered nurses (RNs) assist throughout investigations and other associated procedures. Laboratory technicians conduct laboratory tests and evaluations of ova and sperm. Other technicians may assist in preparing eggs and sperm for IVF, or readying women for GIFT or ZIFT. Pharmacists dispense the many drugs that are required for GIFT, ZIFT, or IVF.

Prevention

Prevention of infertility involves avoiding many of the various problems that can cause infertility. Since sperm count declines with age, insemination is more likely to occur with younger men than older men. Males can preserve maximal fertility by maintaining optimal temperatures in their testicles by wearing non-binding undergarments. People should avoid exposure to coal-based products such as tar and soot as they are associated with infertility. Protecting the testicles from trauma helps to preserve fertility. Immunization for mumps is important.

Women are maximally fertile in the beginning of their third decade of life. Thereafter, conception becomes more difficult. Avoiding or promptly treating sexually transmitted diseases lessens the possibility of endometriosis and pelvic adhesions. Limiting the number of male partners improves fertility as antibodies against sperm will not be formed. Hasty decisions to perform tubal ligations as a means of birth control may be regretted if marital arrangements change. Although tubal ligations can be reversed, subsequent pregnancy rates are not 100%.

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KEY TERMS

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Blastocyst—A cluster of cells representing multiple cell divisions that have occurred in the fallopian tube after successful fertilization of an ovum by a sperm.

Cervix—The opening from the vagina that leads into the uterus.

Embryo—The stage of development of a baby between the second and eighth weeks after conception.

Endometrium—The lining of the uterus.

Fallopian tube—The tube leading from the ovary into the uterus; there are two fallopian tubes.

Fetus—A baby developing in the uterus from the third month to birth.

Ovary—The female organ in which eggs (ova) are stored and mature.

Ovum (plural: ova)—The reproductive cell of the female that contains genetic information and participates in the act of fertilization. Also popularly called the egg.

Semen—The fluid that contains sperm that is ejaculated by the male.

Sperm—The reproductive cell of the male that contains genetic information and participates in the act of fertilization of an ovum.

Spermatogenesis—The process by which sperm develop to become mature sperm, capable of fertilizing an ovum.

Zygote—The result of sperm successfully fertilizing an ovum, the zygote is a single cell that contains the genetic material of both the mother and the father.

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L. Fleming Fallon, Jr., M.D., Ph.D., Dr.P.H.