Infertility is defined as a failure to conceive after 1 year of unprotected, appropriately timed intercourse without conception. The prevalence of infertility among couples in the United States is approximately 10%-15%. Possible contributing factors include advanced maternal age due to delay in child bearing and a decrease in sexual activity with increasing length of relationship. The natural fecundity rate (the percentage of fertile couples achieving a live birth) per month is estimated at 20%-25%. Life table analysis reveals that 64% of women with primary unexplained infertility (when all standard clinical tests yield normal results) and 79% with secondary infertility (when a previous pregnancy has occurred) will conceive within 9 years. Nevertheless, the decision to institute diagnostic tests and treatment should be made on an individual basis. This article will address the basic infertility work-up. Next month we will discuss specific causes and their evaluation.
Physiology
Conception and pregnancy are dependent on a complex interaction of physiologic, anatomic, and immunologic factors. The man requires normal spermatogenesis, reproductive anatomy, and sexual function to provide an adequate number of morphologically normal, motile spermatozoa in the upper vagina of a woman. The woman requires a functionally intact hypothalamic-pituitary-ovarian axis to orchestrate the menstrual cycle and stimulate normal folliculogenesis, ovulation, and a luteal-phase hormonal environment. In order for the egg and sperm to meet in the fallopian tube, the sperm must initially pass through the cervical mucus, which may be impervious, depending on the time of the female’s menstrual cycle. The tube must then be mobile and functional to retrieve the egg. Once fertilized, the “pre-embryo” travels to the uterus where successful implantation is contingent on an adequate hormonally stimulated endometrium, which is maintained by progesterone production from the corpus luteum. A disruption in any of these steps can result in infertility.
Etiology
In 20%-25% of couples, both the man and woman have reproductive abnormalities. Both female and male factors each account for 40% of fertility problems. Other etiologic factors have been studied. Exercise programs can be associated with menstrual disturbances and decreased fertility. Strenuous activity can result in amenorrhea or oligomenorrhea by causing adverse effects on gonadotropins, androgens, estrogens, and progesterone. Cigarette smoking has been shown to affect fertility rates in an inverse ratio; some studies have shown a possible alteration in tubal physiology, transport, and cervical mucus as a result of smoking. Sperm parameters, as shown by semen analysis, have also been adversely affected by cigarette smoking.
Examination
The basic infertility work-up begins with obtaining a comprehensive medical history from both partners. In addition to the usual gynecologic history, it is important to discuss coital frequency and timing, sexual dysfunction, and use of spermicidal lubricants. Other areas of importance are endocrinologic abnormalities including galactorrhea, weight changes, acne, frontal balding, and hirsutism. The man should also give a fertility and sexual history. Also, environmental exposures may lead to an underlying cause. The woman should undergo a thorough physical examination, including a pelvic examination with cultures of Chlamydia, gonorrhea, and, possibly, mycoplasma and urea plasma, as indicated. If the semen analysis reveals abnormalities, the man’s external genitalia should also be examined to exclude serious pathology. The couple’s medical records of diagnostic tests should then be reviewed. It is important to provide appropriate education to assist the infertile patient or couple in the understanding of the problem, evaluation, and treatment proposed. Laboratory testing and procedures will address the etiologic factors.
Next month we will examine male factor, female factor (ovulation, tubal, uterine) and unexplained infertility.
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