Semen Analysis The basic semen analysis measures semen volume, sperm concentration, sperm motility, and sperm morphology (30). Recently revised, the normal values suggested by the World Health Organization (WHO) in 2010 are listed along with the previously published guidelines in Table 32.3 (30,43). Both criteria were developed using fertile men whose semen parameters were in the lowest fifth percentile of the group studied, but values above the reference ranges do not guarantee male fertility. Furthermore, since infertile men were not used to develop the criteria, values below the cutoffs may not necessarily indicate infertility (30). However, significant deviations from the reference limits are generally classified as male factor infertility (44). Given regional differences in semen quality and between laboratories, laboratories are encouraged to develop their own reference ranges. Typically, semen is assessed manually, but computer-aided sperm analysis (CASA) may be used. Limitations of CASA include a lack of standardization among instruments, an inability to differentiate intact from nonintact sperm, possible bias from artifacts during preparation, and a paucity of studies on fertility outcomes in large populations (30).
Abstinence Abstinence of a minimum of 2 to a maximum of 7 days usually is recommended prior to the semen analysis, but the optimal duration is unknown (30). The epididymis stores the equivalent of three ejaculations (29). With prolonged abstinence, sperm overﬂow into the urethra and are ﬂushed out into the urine (30). A study of men attending an infertility clinic found that the total motile sperm count and normal morphology decreased after 10 days’ abstinence in normozoospermic men but after 5 days’ abstinence in oligozoospermic men (45). There are conﬂicting reports regarding the impact of shorter abstinence of 1 or 2 days on semen parameters (45,46), but one study suggested intrauterine insemination success rates might be improved by shortening abstinence times prior to specimen collection (46).
Specimen Collection The specimen should be obtained by masturbation and collected in a clean container kept at ambient temperature (30). The patient should report any loss of the specimen, particularly the first portion of the ejaculate, which contains the highest sperm concentration. Collection may be performed either at home or in a private room near the laboratory. The sample should be taken to the laboratory within 30 minutes to 1 hour of collection to prevent dehydration and degradation. If masturbation into a container is not possible, condoms specially designed for semen analysis should be used rather than latex condoms, which are toxic to sperm. Intercourse to collect the sample is discouraged because of the risk of contamination. Even when the specimen is obtained under optimal circumstances, interpretation of the results of the semen analysis is complicated by variability within the same individual and
Table 32.3 Semen Analysis Terminology and Normal Values
Oligozoospermia Reduced sperm numbers Mild to moderate: 5–20 million/mL Severe: <5 million/mL
Teratozoospermia Increased abnormal forms of sperm
Necrozoospermia All sperm are nonviable or nonmotile
Normal Semen Analysis: World Health Organization
Volume 2mL ≥1.5 mL
Immunobead or mixed antiglobulin <10% coated with antibodies <50% reaction test
Terminology from Hirsh A. Male infertility. BMJ 2003;327:669–672, with permission.
wide differences in normal semen parameters. Semen parameters may vary widely from one man to another and among men with proven fertility. In many circumstances, several specimens are necessary to verify an abnormality (30).