[An analysis of donor semen quality in Chongqing Human Sperm Bank]

To evaluate the quality of the donor semen in Chongqing Human Sperm Bank and the influence of age on semen parameters.

We collected semen samples from 899 donors in Chongqing Human Sperm Bank and divided them into five groups according to the age of the semen donors: 22－25, 26－30, 31－35, 36－40, and >40 years old. Using the Makler Counting Chamber, we measured the semen volume, percentage of progressively motile sperm (PMS), total motile sperm, sperm concentration, total sperm count per ejaculate, and percentage of morphologically normal sperm (MNS). Then, we compared the semen parameters obtained with the fifth percentile and median reference values published in the WHO Laboratory Manual for the Examination and Processing of Human Semen-5th Ed (WHO 5th Ed) and among different age groups using the Kruskall-Wallis H test.

The semen volume (1.8 ml), sperm concentration (25.0 × 10⁶/ml), total sperm count (100.7 × 106/ejaculate) and MNS (4.3%) in the semen samples of the 899 donors were obviously higher than the fifth percentile values published in the WHO 5th Ed, and so were the first three parameters (4.0 ml, 88.0 × 10⁶/ml, and 333.7 × 106/ejaculate) than the WHO median reference values. PMS (31.0%) and total motile (38.0%) were lower than the WHO fifth percentile values and so was MNS (11.6%) than the WHO median reference value. PMS (55.0%) and total motile sperm (61.0%), however, were coincident with the median reference values of WHO 5th Ed. Statistically significant differences were observed among the 22－25, 26－30, 31－35, 36－40 and >40 years old groups in perm concentration (88.0 ［1.0－270.0］ vs 96.0 ［5.0－335.0］ vs 100.0 ［3.0－200.0］ vs 105 ［15.0－225.0］ vs 90.0 ［22.0－159.0］ × 10⁶/ml, P < 0.05), but not in the semen volume, PMS, total sperm motility, total sperm count or MNS (P > 0.05).

The donor semen in Chongqing Human Sperm Bank is generally of high quality. Sperm concentration significantly increases with age but decreases in men aged >40 years.