Male Infertility

Conception requires sperm to be produced, mature, transported, and deposited effectively. Male infertility can therefore arise from impaired sperm production, abnormal sperm function, or failure of sperm delivery. The evaluation is directed at identifying which part of that pathway has failed; it is not simply a search for a low testosterone level. The hypothalamic-pituitary-gonadal axis coordinates sperm production. Gonadotropin-releasing hormone stimulates pituitary release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). LH stimulates Leydig cells to produce testosterone, while FSH acts on Sertoli cells within the seminiferous tubules to support sperm development. High intratesticular testosterone is needed for spermatogenesis, so a normal serum testosterone value does not by itself prove that sperm production is intact. Azoospermia is the complete absence of spermatozoa in the ejaculate on at least two separate semen analyses. It is not the same as oligospermia, in which sperm are present but reduced in number, and it is not synonymous with every form of male infertility. Two broad mechanisms organize the clinical reasoning: - Non-obstructive azoospermia (NOA): the testes produce too few sperm, or none that can...