For Clinicians · Decision Aid

Azoospermia & Severe Oligospermia Pathway

Differentiate obstruction from impaired production, and apply the genetic testing the AUA/ASRM guideline recommends at very low counts.

Confirm first. Azoospermia requires confirmation on a repeat sample with examination of a centrifuged pellet. Do not act on a single absent result. This tool orients the workup; it does not replace exam and specialist evaluation.

Sperm concentration

Semen volume

Serum FSH

Testicular volume / consistency on exam

Vas deferens palpable bilaterally? (absent vas suggests CBAVD)

Typical patterns (AUA/ASRM)

	Obstructive (OA)	Non-obstructive (NOA)
Testis volume	Normal	Often small / atrophic
FSH	Normal (< ~7.6)	Often elevated
Semen volume	Normal, or low if distal obstruction / CBAVD	Normal
Genetic testing	CFTR (incl. 5T) if vasal agenesis	Karyotype + Y-microdeletion

Evidence base

Schlegel PN, Sigman M, Collura B, et al. Diagnosis and treatment of infertility in men: AUA/ASRM guideline part I. Fertil Steril. 2021. — Initial split of azoospermia by exam, semen volume, pH, FSH; OA vs NOA features.
Brannigan RE, Hermanson L, Kaczmarek J, et al. Updates to male infertility: AUA/ASRM guideline (2024). J Urol. 2024. doi:10.1097/JU.0000000000004180. — Karyotype for azoospermia or < 5 M/mL with elevated FSH/atrophy; Y-microdeletion for azoospermia or ≤ 1 M/mL; CFTR for vasal agenesis/obstructive azoospermia.