Reference values for basic ejaculate analysis from fertile men: russian regional characteristics (multicenter cross-sectional retrospective study)

Introduction. The current “WHO Manual for the Laboratory Examination and Processing of Human Semen” (6th edition, 2021) states the variability and low predictive ability of traditionally ejaculate parameters (ejaculate volume, sperm concentration, motility and morphology), abandons the concept of “norm”, replacing it with 5% and 95% percentiles, and recommends the formation of regional criteria for reference ranges.

Aim. To establish reference ranges for basic indicators of ejaculate analysis from fertile Russian men to improve the clinical and economic efficiency of providing medical care to infertile couples.

Materials and methods. A multicenter cross-sectional retrospective study was carried out. Based on the results of a clinical and laboratory examination, a group of fertile men was formed who met the following criteria:

• confirmed pregnancy in the wife (regular partner) according to hCG and/or ultrasound;
• ejaculate analysis was performed in specialized andrological laboratories according to WHO protocols;
• between the date of the study performed and the estimated date of pregnancy there was no more than 3 months (the analysis could be performed before the date of pregnancy, or after the fact of pregnancy was established);
• pregnancy in a natural cycle;
• absence of any specific treatment at least 3 months before the date of pregnancy;
• pregnancy outcome (childbirth, medical abortions, miscarriages, anembryonic pregnancies) was not taken into account.

In total, the sample included 445 men who was examined in the health care facility where the authors of the article worked regarding sexual dysfunction, chronic prostatitis, or miscarriage.

Results. The reference values of basic ejaculate parameters of fertile Russian men differed from the international data presented in the WHO Guidelines, 6th edition (2021). The lower 5% percentile in Russians was higher for sperm concentration (20 and 16 million/ ml, respectively) and ejaculate volume (1.7 and 1.4 ml, respectively), but less for the proportion of sperm with progressive motility (24 and 30%, respectively). Moreover, our values were very close to those from the WHO Guidelines, 4th edition (1999): 20 million/ml, 2 ml and 25%, respectively. The lower 5% percentile of the number of sperm with progressive motility was 21 million, while the minimum value was 5.2 million. The upper 95% percentile of the percentage of abnormal forms was equal to 99%, which indicates the low predictive ability of this indicator in the assessment possibility of conception. It should be remembered that a “fertile man”, i.e. the man who caused the pregnancy is not identical to the concept of a “healthy” man in the reproductive sense, since in 30-40% of cases, anembryonic pregnancy is associated with low sperm quality (ESHRE, 2022).

Conclusion. Our data suggest that for Russian men, the following threshold values foe sperm analysis should be used: for the term “oligospermia”, ejaculate volume is <1.7 ml, “oligozoospermia” means the sperm concentration <20 million/ml, for “asthenozoospermia” is defined as <24% progressively sperm motility, and “teratozoospermia” is diagnosed when <1% of morphologically normal sperms with Papanicolaou staining using “strict” criteria. In 95% of fertile men, a number of sperms with progressive motility was at least 21 million, when in 5% it was from 5 to 20 million. A value <5 million indicate a low probability of conception.