The World Health Organization (WHO) has defined infertility as the inability of a sexually active couple to achieve pregnancy despite unprotected intercourse during the fertile phase of the menstrual cycle for a period of greater than 12 months. The percentage of couples seeking medical treatment for infertility is estimated at 4% to 17%.
The estimates of prevalence rates of infertility and subfertility depend crucially upon the method used to define these conditions. The WHO definition was based on studies that used time to pregnancy estimations and found the probability of conception to be 20% per cycle or ∼85% to 90% per year. Even among couples who do not conceive within 12 months, 55% have a live birth within the next 36 months. When the duration of infertility exceeds 4 years, the conception rate per month drops to 1.5%.
In 20% of infertile couples, the primary problem resides in the male partner; in an additional 26%, problems reside in both the male and the female partner; thus, the male partner contributes to infertility in about half the couples. The occurrence of infertility substantially affects a couple’s relationship, quality of life, and health care expenditures.
COMMON DIAGNOSES IN MEN BEING EVALUATED FOR INFERTILITY
| Diagnostic Category | Incidence (%) |
|---|---|
| Idiopathic infertility | 50-60 |
| Primary testicular failure (chromosomal disorders including Klinefelter’s syndrome, Y chromosome microdeletions, undescended testis, irradiation, orchitis, drugs) | 10-20 |
| Genital tract obstruction (congenital absence of vas, vasectomy, epididymal obstruction) | 5 |
| Coital disorders | <1 |
| Hypogonadotropic hypogonadism (pituitary adenomas, panhypopituitarism, idiopathic hypogonadotropic hypogonadism, hyperprolactinemia) | 3-4 |
| Varicocele[*] | 15-35 |
| Other (sperm autoimmunity, drugs, toxins, systemic illness) | 5 |
Although varicoceles are observed with higher frequency in infertile and subfertile men than in fertile men, their role and contribution to infertility remains unclear.
Correctable or treatable causes of infertility, such as gonadotropin deficiency and obstruction, are present in only a small number of men, but it is important to recognize them because effective treatment modalities are available. Varicoceles are present in 10% to 30% of men with infertility; their role, if any, in the pathophysiology of male infertility remains unclear. An increasing number of genetic disorders are being implicated in specific abnormalities of germ cell development; in addition, a number of systemic disorders nonspecifically affect spermatogenesis. Of these, Klinefelter’s syndrome and Y chromosome microdeletions are the most prevalent disorders, together accounting for 10% to 20% of patients . Although the prevalence of antisperm antibodies in infertile men is higher than that in fertile men, the mechanisms by which antisperm antibodies cause infertility are unclear.