Azoospermia may be classified into three categories: pre-testicular, testicular, and post-testicular diagnoses Pre-testicular causes of azoospermia include endocrine abnormalities having adverse effects on spermatogenesis (secondary testicular failure). Testicular causes of azoospermia (primary testicular failure) encompass disorders of spermatogenesis intrinsic to the testes. Post-testicular causes of azoospermia relate to ejaculatory dysfunction or ductal obstruction that impairs sperm transit. A classification system employed commonly in clinical practice, and the basis for which this document is organized, distinguishes between obstructive azoospermia (OA) and nonobstructive azoospermia (NOA). NOA can be further divided into central NOA and testicular NOA. Generally, men with azoospermia, normal size testes, and normal serum follicle-stimulating hormone (FSH) levels have normal spermatogenesis and are more likely to have OA, while men with a significant elevation in FSH have testicular failure, and thus testicular NOA. Low levels of gonadotropins and low or low-normal testosterone (T) suggest a central NOA diagnosis. The etiological diagnosis is made based upon a detailed clinical history, physical exam, and endocrine evaluation, in addition to supplemental testing.
A standard reproductive history and physical exam should be performed as per the American Society for Reproductive Medicine (ASRM) Practice Committee report ‘‘Diagnostic evaluation of the infertile male: a committee opinion’’ (3). Hormonal abnormalities of the hypothalamicpituitary-gonadal axis are well recognized causes of male infertility and represent a necessary component of the evaluation of the azoospermic male. For azoospermic men, the minimum initial hormonal evaluation should include measurement of serum FSH and total T concentrations, although most cases will require complete hormone testing, including luteinizing hormone (LH), free T, estradiol, and prolactin. Whereas some men with abnormal spermatogenesis may have a serum FSH level within normal limits, an elevated serum FSH concentration indicates an abnormality in spermatogenesis. While various labs have different reference ranges, most experts state that an FSH >7.6 mIU/mL would be considered abnormal