Non-obstructive azoospermia (NOA)

Non-obstructive azoospermia means the testis itself is producing very few or no sperm, rather than sperm being blocked from leaving. Causes include genetic conditions such as Klinefelter syndrome or Y-chromosome microdeletions, hormonal problems such as hypogonadotropic hypogonadism, undescended testes in childhood, previous chemotherapy or radiotherapy, or, in many cases, no identifiable cause. Evaluation usually includes hormone testing, scrotal ultrasound, karyotype and Y-chromosome microdeletion testing, with genetic counselling offered where a genetic cause is found or suspected. Sperm retrieval is possible for some but not all men with non-obstructive azoospermia; microdissection TESE gives the best chance of finding sperm in this group, but a diagnosis of non-obstructive azoospermia does not guarantee that sperm will be found.

Also known as: NOA, non-obstructive azoospermia diagnosis

Last reviewed: 9 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.