Frequency of semen analyses If values are normal according to WHO criteria, one test should suffice. If the results are abnormal, semen analysis should be repeated. It is important to distinguish between oligozoospermia (< 15 million spermatozoa/mL), astheno- zoospermia (< 40% motile spermatozoa), and teratozoosper- mia (< 4% normal forms). Quite often, all three pathologies occur simultaneously as oligo-astheno-teratozoospermia (OAT) syndrome. In extreme cases of OAT syndrome (< 1 million spermatozoa/mL), just as with azoospermia, there is an increased incidence of genetic abnormalities and obstruc- tion of the male genital tract.
Hormonal investigation Endocrine malfunctions are more prevalent in infertile men than in the general population, but are still quite uncommon. Hormonal screening can be limited to determining follicle stimulating hormone (FSH), luteinising hormone (LH), and testosterone levels in case of abnormal semen parameters. In men diagnosed with azoospermia or extreme OAT, it is important to distinguish between obstructive and non- obstructive causes. A criterion with reasonable predictive value for obstruction is a normal FSH with bilaterally normal testicular volume. However, 29% of men with a normal FSH appear to have defective spermatogenesis.
Hypergonadotrophic hypogonadism (elevated FSH/LH) Impaired spermatogenesis associated with elevated levels of gonadotrophins is a common problem and it is due to pri- mary testicular failure. Causes include:
congenital – Klinefelter’s syndrome, anorchia, cryp-