Infertility - Causes and Testing

Infertility is a complex disorder with significant medical, psychosocial, and economic aspects. Infertility is a unique medical condition because it involves a couple, rather than a single individual. It is defined as a failure of a couple to conceive after 12 months of regular intercourse without use of contraception. The diagnosis of infertility may be suspected after only six months of unprotected intercourse without conception.

The World Health Organization (WHO) task force on Diagnosis and Treatment of Infertility performed a study to determine the medical conditions contributing to infertility. In developed countries, female factor infertility was reported in 37 percent of infertile couples, male factor infertility in 8 percent, and both male and female factor infertility in 35 percent. The most common identifiable female factors found in the WHO study, were: ovulatory disorders (25%), endometriosis (15%), pelvic adhesions (12%), tubal blockage (11%), other tubal abnormalities (11%), and hyperprolactinemia (7%).

Although a variety of tests are available for evaluating female infertility, it may not be necessary to have all of these tests. Healthcare providers usually begin with a medical history, a thorough physical examination, and some preliminary tests. A woman's past health and medical history may provide some clues about the cause of infertility. The healthcare provider will ask about childhood development; sexual development during puberty; sexual history; illnesses and infections; surgeries; medications used; exposure to certain environmental agents (alcohol, radiation, steroids, chemotherapy, and toxic chemicals); and any previous fertility evaluations. A physical examination usually includes a general examination, with special attention to any signs of hormone deficiency or signs of other conditions that might impair fertility. Blood tests can provide information about the levels of several hormones that play a role in female fertility; in women, key hormones are produced by the hypothalamus, the pituitary gland, and the ovaries. These hormones include follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin.

An elevated FSH level is an indicator of decreased ovarian reserve (eg, a decreased number of eggs) and may indicate poor egg quality. Ovulation (the release of an egg from an ovary) is essential for fertility. Abnormalities of ovulation can often be determined from a woman's menstrual history or hormone levels such as the pre-ovulatory LH surge or luteal phase. Amenorrhea (absent menstrual periods) usually signals an absence of ovulation, which can cause infertility. Oligomenorrhea (irregular menstrual cycles) can be a sign of irregular ovulation; although oligomenorrhea does not make pregnancy impossible, it can interfere with the ability to become pregnant.

Monitoring of basal body temperature (measured before getting out of bed in the morning) was previously recommended to determine if ovulation occurred. A woman's temperature usually rises by 0.5ºF to 1.0ºF after ovulation. However, basal body temperature patterns can be difficult to interpret and are not generally recommended in the evaluation of infertility.

Uterine abnormalities that can contribute to infertility include congenital structural abnormalities, such as a uterine septum (a band of tissue that makes the uterine cavity small); abnormalities linked to exposure to diethylstilbestrol (DES) (a hormone used in the past to prevent miscarriage), which can cause a T-shaped uterus; fibroids; polyps; and structural abnormalities that can result from gynecologic procedures. Scarring and obstruction of the fallopian tubes can occur as a result of pelvic inflammatory disease, endometriosis or pelvic adhesions (scar tissue) from abdominal infection or surgery.

Genetic testing may be recommended if there is a suspicion that genetic or chromosomal abnormalities are contributing to infertility. These tests usually require a small blood sample, which is sent to a laboratory for evaluation. Although assisted reproductive techniques may be able to overcome genetic or chromosomal abnormalities, there is a possibility of transferring the abnormality to a child. Genetic counseling is often recommended to educate a couple about the possibility of parent to child transmission, possible impact of the abnormality, and treatments available to prevent parent-to-child transmission.

Unexplained infertility is the diagnosis given to couples after a thorough evaluation has not revealed a cause. Many cases of unexplained infertility may be due to small contributions from multiple factors (borderline semen analysis, subtle changes in follicle dynamics, etc).