Obstructive azoospermia (OA)

Obstructive azoospermia means sperm are being produced normally in the testis but are blocked from reaching the ejaculate, because of a blockage anywhere from the epididymis to the ejaculatory ducts. Causes include past infection, previous vasectomy, congenital absence of the vas deferens (often linked to CFTR gene changes), or scarring from surgery. Because sperm production itself is usually normal, sperm can often be retrieved directly from the epididymis or testis for use with ICSI, and in some cases the blockage can be surgically corrected instead. Hormone levels are typically normal in obstructive azoospermia, which helps distinguish it from non-obstructive azoospermia on initial testing.

Also known as: OA, 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.