Glossary of Azoospermia & Male Infertility Terms

Plain-language definitions of the medical terms you'll encounter throughout this guide.

Last updated: May 2026 Reading time: ~6 min

A–C

Azoospermia: The complete absence of sperm in the ejaculate, confirmed by examining the sample under a microscope after centrifugation. Affects roughly 1% of all men and 10–15% of infertile men.
cfDNA (Cell-Free DNA): Fragments of DNA found floating in body fluids — including seminal fluid — that are not contained inside cells. Sperm-derived cfDNA in semen can be analyzed (e.g., by NOA Guide) to estimate the chance of finding sperm during surgical retrieval.
Cryptozoospermia: An extreme form of low sperm count where sperm are not seen in the initial semen analysis but are found after the sample is centrifuged. Sometimes confused with true azoospermia.

D–F

Ejaculate: The fluid produced during male orgasm, also called semen. Most of the volume comes from the seminal vesicles and prostate, not the testicles.
FNA Mapping (Fine-Needle Aspiration Mapping): An office-based, non-surgical procedure that uses a fine needle to sample sperm from many specific locations across the testicle to map where sperm production exists. Pioneered by Dr. Paul Turek. Read more →
FSH (Follicle-Stimulating Hormone): A hormone produced by the pituitary gland that stimulates sperm production. High FSH (often >7 mIU/mL) usually indicates the testicles are working hard but producing little sperm — a hallmark of non-obstructive azoospermia.

G–L

Hypogonadism: A condition where the body produces too little testosterone and/or sperm. Can be primary (testicle problem) or secondary (pituitary/hypothalamus problem).
ICSI (Intracytoplasmic Sperm Injection): An IVF technique where a single sperm is injected directly into an egg using a microscopic needle. ICSI made parenthood possible for many men with severe male-factor infertility because only one viable sperm is needed per egg.
IVF (In Vitro Fertilization): A multi-step process where eggs are retrieved from the ovaries, fertilized with sperm in a laboratory, and the resulting embryo is transferred to the uterus. Read more →
Klinefelter Syndrome (47,XXY): A genetic condition where a man has an extra X chromosome. It causes small testicles and very low sperm production, but ~50% of men with Klinefelter still have sperm successfully retrieved at microTESE.
LH (Luteinizing Hormone): A pituitary hormone that stimulates testosterone production in the testicles. Measured alongside FSH and testosterone to assess testicular function.

M–P

MicroTESE (Microdissection Testicular Sperm Extraction): The gold-standard surgical procedure for retrieving sperm in non-obstructive azoospermia. A reproductive urologist opens the testicle and uses an operating microscope to identify and extract individual seminiferous tubules most likely to contain sperm. Success rates ~40–60%. Read more →
NOA (Non-Obstructive Azoospermia): Azoospermia caused by impaired sperm production in the testicles. Reproductive plumbing is intact, but the testicles either don't produce sperm or produce so little that it never reaches the ejaculate. Read more →
OA (Obstructive Azoospermia): Azoospermia caused by a blockage between the testicles and the urethra. Sperm production is normal, but sperm cannot reach the ejaculate. Often surgically correctable, with retrieval success near 100%. Read more →
PESA (Percutaneous Epididymal Sperm Aspiration): A needle-based sperm retrieval procedure that aspirates sperm from the epididymis. Used for obstructive azoospermia.

R–T

Reproductive Urologist: A urologist with additional fellowship training in male infertility and microsurgery. The right specialist for any azoospermia diagnosis — not a general urologist. Read more →
Semen Analysis: The lab test that examines a sperm sample under a microscope for count, motility, and morphology. The first test ordered when male infertility is suspected. Standard analyses examine less than 1% of the sample, which is why a single test reporting "no sperm" doesn't necessarily mean zero sperm exist.
Seminiferous Tubules: The tiny tubes inside the testicles where sperm are produced. Healthy tubules are full and plump; non-productive tubules are thin and translucent. MicroTESE relies on visually identifying the difference.
Sertoli-Cell-Only Syndrome (SCOS): A testicular biopsy finding where only Sertoli cells (the support cells) are present and germ cells (sperm-producing cells) are missing. Can be focal — meaning sperm may still exist in small pockets that microTESE can find.
STAR Test: An AI- and microfluidics-based extended sperm search developed at Columbia University, designed to find rare sperm that human technicians miss. Read more →
TESA (Testicular Sperm Aspiration): A needle-based procedure to aspirate sperm directly from the testicle. Less invasive than microTESE but with lower yields in NOA.
TESE (Testicular Sperm Extraction): An open surgical biopsy of the testicle to extract sperm. The non-microsurgical version of microTESE; less precise and removes more tissue.

U–Z

Varicocele: An enlargement of the veins in the scrotum, similar to varicose veins. Common (~15% of men) and can sometimes impair sperm production. Surgical repair may help in select cases. Read more →
Y-Chromosome Microdeletion: A genetic deletion of a small region on the Y chromosome (AZFa, AZFb, or AZFc) that disrupts sperm production. AZFc deletions still allow some sperm retrieval; complete AZFa or AZFb deletions usually mean no sperm will be found.

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