Iris de Nie

12 C H A P T E R 1 Figure 4. Spermatogenesis. By courtesy of Encyclopædia Britannica, Inc. , copyright 2011; used with permission. It is estimated that healthy birth-assigned males produce around 45 million spermatozoa per testicle per day. 9 To determine the semen quality of ejaculated samples, different parameters are used: volume of the semen sample, sperm concentration per milliliter, percentage of progressive motility, total sperm number per ejaculate and total motile sperm count. Total sperm number is calculated by multiplying the sample volume with the sperm concentration. Total motile sperm count (TMSC) is calculated by multiplying the sample volume, sperm concentration and the percentage of progressive motility, divided by 100%. The World Health Organization (WHO) assessed semen quality in the general population and determined reference values for human semen, based on their data (Table 1). 10,11 Since TMSC is derived from the absolute value of three other semen parameters, no reference value for TMSC is determined by the WHO. However, TMSC is a commonly used parameter in clinical practice and previous studies found that TMSC is a better indicator for the severity of male factor infertility than the WHO classification system. In addition, it has been shown that chances for spontaneous pregnancy are significantly lower in couples with a TMSC below 5 million compared to those with a TMSC above 5 million. 12,13 Table 1. World Health Organization (WHO) data on human semen quality 10,11 Volume (ml) Sperm concentration (10 6 /ml) Progressive motility (%) Total sperm number (10 6 /ejaculate) Total motile sperm count (10 6 /ejaculate) Semen quality in general population of unscreened men (median, IQR) 3.2 (2.2-4.2) 64 (36-100) 57 (49-65) 196 (101-336) 113 (54–201) Lower reference limit for human semen 1.5 15 32 39 N/A