[Analysis of seminal fluid: modern aspects of an old examination]

Semen analysis stands as the most widely employed test for the diagnosis of male infertility. Subjectivity of evaluation and intra-individual variations of sperm concentration and motility are major limitations of this technique. Intra-individual variations are due to spontaneous circannual rhythmicity, to collection artifacts or to several environmental, physiological and pathological factors. The diagnostic and prognostic usefulness of semen analysis is related to strict compliance with the guidelines recently suggested by the World Health Organization. In recent years, the development of computerized systems provides an objective and rapid method for semen analysis, suitable for the study of more sophisticated parameters of sperm motility. Electron microscopy should be performed for the evaluation of ultrastructural abnormalities of spermatozoa in men with infertility of uncertain origin.