Because male infertility is common, it is important to also perform a semen analysis when initiating evaluation of the female partner. The semen specimen is usually obtained by masturbation after 2 to 3 days of abstinence; frequent ejac-ulation may lower the sperm concentration. It is important to collect the entire ejaculate, because the first part contains the greatest density of sperm. Analysis of the specimen should be performed within 1 hour of ejaculation (see Table 38.1). The standard semen analysis evaluates the quantity and quality of seminal fluid, sperm concentra-tion, and sperm motility and morphology. Normal semen measurements have been established by the World Health Organization (Table 38.2). A normal semen analysis excludes a male cause for infertility in more than 90% of heterosexual couples. Certain abnormalities identified by the semen analysis are associated with specific etiologies of male infertility (Table 38.3). Sperm function can be further evaluated with specialized diagnostic tests, but these tests are not routinely used.
Besides the semen analysis, the postcoital test has historically been used to evaluate sperm concentration and their interaction with the cervical mucus. To perform this test, a sample of cervical mucus must be obtained 2 to 12 hours after intercourse that occurs 1 to 3 days prior to ovulation. The sample is placed on a glass slide and exam-ined under a microscope. Standard criteria include the presence of at least 5 motile sperm per high-powered field. However, the diagnostic utility and validity of this test is limited; thus, its routine use is not indicated. Furthermore, conventional fertility treatments such as intrauterine insem-ination and in vitro fertilization (IVF) bypass any abnormal-ities of the cervix or cervical mucus.
If the results of the semen analysis are abnormal, it should be repeated in 1 to 2 weeks. Persistent abnormali-ties in the semen necessitate further investigation. The male partner should be evaluated by a urologist or repro-ductive endocrinologist who specializes in male infertility. Occasionally, male infertility may be the presenting sign of a serious medical condition, such as testicular cancer or a pituitary tumor. Etiologies of male infertility include con-genital, acquired, or systemic disorders that can be grouped into the following categories: hypothalamic-pituitary disease that causes gonadal dysfunction (1% to 2%), testic-ular disease (30% to 40%), post-testicular defects that cause disorders of sperm transport or ejaculation (10% to 20%), and unexplained infertility (40% to 50%).
Abnormalities in spermatogenesis are a major cause of male infertility. Unlike oocytes, which undergo development ina cyclic fashion, sperm are being produced constantly by the testes. As sperm develop within the germinal epithe-lium of the testis, they are released into the epididymis where maturation occurs before ejaculation.
Sperm production and development takes approximately 70 days. Therefore, abnormal results of the semen analysis reflect events that occurred more than 2 months before the specimen collection.
Alternatively, a minimum of 70 days is required to observe changes in sperm production following initiation of any therapy.
Further evaluation of the infertile male includes endocrine and genetic testing. Endocrine evaluation is appropriate for individuals with abnormal sperm concentra-tions or signs of androgen deficiency. Serum testosterone, FSH, and LH levels will identify primary hypogonadism (low testosterone, or elevated FSH and LH) or secondary hypogonadism (low testosterone, FSH, and LH). A low LH level in the presence of oligospermia (sperm concentration less than 5 million/mL) and a normal testosterone level may indicate exogenous steroid use. A serum prolactin level should be assessed in men with low testosterone levels.
Genetic abnormalities may affect sperm production or trans-port. Genetic testingis indicated in men withazoospermia(no sperm) and severe oligospermia. The most common abnormalities identified include gene mutations in the cys-tic fibrosis transmembrane conductase regulator (CFTR), somatic and sex chromosome abnormalities, and micro-deletions of the Y chromosome. Men with mutations in one or both copies of the CFTR gene often exhibit congenital bilateral absence of the vas deferens or other obstructive defects, and many have no pulmonary symptoms. A karyo-type may reveal abnormalities, such as Klinefelter syndrome (47 XXY) or chromosome inversions and translocations. Special testing must be performed to search for Y chromo-some microdeletions, because they are not detected by rou-tine karyotype analysis; these microdeletions are associated with altered testicular development and spermatogenesis. If a genetic condition is identified, genetic counseling is strongly recommended.
Men with azoospermia can be further evaluated by two diagnostic procedures. If an obstructive process is suspected (obstructive azoospermia), then sperm should accumu-late just before the obstruction. For example, men with congenital absence of the vas deferens or those who underwent a vasectomy have a swollen epididymis where constant production of sperm results in a small collection. Percutaneous epididymal sperm aspiration (PESA) or microsurgical epididymal sperm aspiration (MESA) procedures can retrieve motile, healthy sperm. If no obstruc-tion is present (nonobstructive azoospermia) and a testicu-lar abnormality is suspected, a testicular biopsy may identify a few sperm present in the seminiferous tubules. With either procedure, small numbers of sperm are obtained compared to a normal ejaculated specimen. These retrieved sperm can be used to try to achieve pregnancy; however, the female partner must undergo IVF, and a single sperm is used to fertilize a singe oocyte (intracytoplasmic sperm injection).