a conventional semen analysis is conducted in order to evaluate the basic semen parameters (semen volume, sperm count, motility, morphology by Strict Tygerberg Criteria, vitality) according to the approved guidelines of ESHRE and WHO, i.e. by expert laboratory technicians using miscroscopic assessment and NOT by automated systems (Computer Assisted Sperm Analysis).
Only the candidates whose semen quality is found high above the internationally recognized reference ranges are selected.
Sperm function tests: several sperm function tests, evaluating for instance the ability of the spermatozoa to perform the acrosome reaction or sperm DNA integrity, are applied in view of selecting the samples exhibiting the best fertility potential.
Post thaw recovery and longevity tests: given that all donor semen samples may be safely provided only after freeze-thawing, a post thaw recovery and longevity test is being performed. Since the endurance of human spermatozoa under deep freezing conditions cannot be predicted, the performance of this test determines the samples that sustain a high percentage of motile spermatozoa surviving for many hours after thawing, in order to increase the fertilization rates.
Microbiological screening: a complete microbiological examination is performed, testing for the presence of fungi, Trichomonas, common bacteria (aerobic-anaerobic) and Mycoplasma/Ureaplasma, Chlamydia.