DEFINITION OF SECRETORY AZOOSPERMIA AND MAIN HISTOPATHOLOGICAL SYNDROMES

Secretory azoospermia (nonobstructive azoospermia) is diagnosed by the absence of sperm in semen after centrifugation, a normal seminal pH, and absence of extratesticular genital duct obstruction, as detected by physical, biochemical, ultrasonography, and surgical inspection. Secretory azoospermia may be primary or secondary, and the absence of sperm in semen is caused by inefficient, deficient, or absent germ cell proliferation, meiosis, and differentiation.

Based on the diagnostic testicular biopsy, three major histopathological syndromes are recognized in secretory azoospermia, Sertoli cell–only syndrome, maturation arrest, and hypospermatogenesis. Sertoli cell–only syndrome is characterized by the exclusive presence of Sertoli cells and complete absence of germ cells; maturation arrest is characterized by the presence of Sertoli cells and diploid germ cells (spermatogonia or/and primary spermatocytes); and hypospermatogenesis is characterized by a global reduction in the number of germ cells, causing a decreased production of spermatids and spermatozoa (Figure 53.1).

Microscopical observation of at least 100 seminiferous tubule sections per patient with secretory azoospermia shows that Sertoli cell–only syndrome, maturation arrest, and hypospermatogenesis may be complete or incomplete syndromes (Figure 53.2). In complete syndromes, all seminiferous tubules present the same cell types, whereas in incomplete syndromes a minority of the seminiferous tubules (at least one of a hundred) present a different cytologic picture. This indicates that the diagnostic testicular biopsy is just representative of the clinical situation, once a single isolated testicular biopsy might eventually not reflect the entire testicular situation (Figure 53.3).