Non-Obstructive Azoospermia (NOA)

NOA occurs when the testes fail to produce enough sperm to appear in the ejaculate, unlike obstructive azoospermia where production is normal but the pathway is blocked. Causes include genetic conditions (Klinefelter syndrome, Y-chromosome microdeletions), prior chemotherapy, hormonal deficiencies, and idiopathic testicular failure.

Diagnosis requires a semen analysis showing zero sperm plus elevated FSH levels and possibly a testicular biopsy or genetic testing.

Treatment often involves micro-TESE, a microsurgical procedure to retrieve sperm directly from testicular tissue, which succeeds in roughly 40–60% of cases.