Azoospermia is a semen analysis finding, not a diagnosis in itself. Semen can look, feel and measure completely normally, because most of its volume comes from the seminal vesicles and prostate rather than the testes. The only way to know whether sperm are present is a lab test.
It is more common in fertility clinics than most men assume: a classic series put it at 10 to 20% of men presenting for infertility investigation.1 In that series of 133 azoospermic men, 37% had a blockage and 63% had testicular failure,1 which is why the first job is always working out which type you have.
The label has to be earned. One empty sample can reflect a collection problem, a recent illness or a lab issue, so clinics normally repeat the analysis and check a spun-down sample before drawing conclusions.
What causes azoospermia?
Causes fall into two camps: a blockage somewhere in the plumbing, or a problem with sperm production itself. Hormonal causes, including testosterone and anabolic steroid use, sit within the second group.
Obstructive azoospermia means the testes are producing sperm but something stops them reaching the ejaculate. Vasectomy is the obvious example; others include scarring after infection and being born without the vas deferens on both sides, which accounted for a third of the obstructed men in Jarow's series.1
Non-obstructive azoospermia means the testes make very few or no sperm. Genetic conditions, undescended testes, chemotherapy or radiotherapy and hormonal problems can all sit behind it. One cause worth naming plainly: testosterone taken from outside the body switches off the brain signals that drive spermatogenesis, which is why the Endocrine Society recommends against starting testosterone in men planning fertility in the near term.4
- Obstructive: sperm are made but blocked (vasectomy, scarring after infection, congenital absence of the vas deferens)
- Non-obstructive: the testes make few or no sperm (genetic causes, testicular damage, cancer treatment)
- Hormonal: the signals from the brain to the testes are too low, including when testosterone or steroids are taken
How is azoospermia diagnosed?
After a repeat semen analysis, a specialist examines the testes, checks hormones and often arranges genetic tests. Testis size and FSH levels are the most telling early clues.
In Jarow's study, testicular size, semen volume and FSH all differed significantly between men with a blockage and men with testicular failure. An FSH below twice the upper limit of normal, together with testes that had not shrunk, was the best predictor of a blockage.1
Genetic testing is commonly offered in non-obstructive cases, because the result can change both the treatment plan and what might be passed on to a son. The EAU guideline also stresses that every infertile man deserves a full urological assessment, partly because male infertility can flag other health problems.3
Can men with azoospermia still father children?
Often, yes. Blockages can sometimes be repaired or bypassed, and in non-obstructive azoospermia surgeons find sperm in the testes in roughly half of procedures.
Testicular sperm extraction (TESE) takes small samples of testicular tissue to look for pockets of sperm production. A 2019 meta-analysis of 117 studies found sperm in 47% of TESE procedures in non-obstructive azoospermia, with no clear difference between conventional and microdissection techniques; larger testes predicted better odds.2
Any sperm found are used for ICSI, where a single sperm is injected into an egg. Live birth rates in that analysis were around 24% per ICSI cycle.2 The EAU guideline names conventional or microdissection TESE as the surgical options of choice for non-obstructive azoospermia.3
When should you see a doctor?
If a semen analysis shows no sperm, ask for a referral to a urologist or andrologist rather than waiting. The sooner the type is identified, the sooner you know your real options.
Bring a list of medicines, supplements, any testosterone or steroid use, past groin or testicular surgery, mumps, undescended testes and cancer treatment. None of this is about blame; it is simply the information that narrows the cause fastest.
If you have been using testosterone or anabolic steroids, say so. Plan any changes with a doctor rather than stopping abruptly, and ask what recovery of sperm production might look like in your case.
Common questions
Can you have azoospermia and still ejaculate normally?
Yes. Most of the fluid comes from the seminal vesicles and prostate, so volume, colour and sensation can all seem normal. Only a lab test shows whether sperm are present.
Is azoospermia permanent?
Not always. Some blockages can be repaired, hormone-related causes may respond to treatment, and even when production is very low, sperm can often be retrieved surgically for IVF with ICSI.2 A specialist can tell you which applies to you.
Does a vasectomy cause azoospermia?
Yes, that is its purpose: it deliberately creates obstructive azoospermia. Clinics check semen after the procedure to confirm no sperm remain before it is relied on for contraception.
Read more on this
Lifestyle factors that affect male fertility: a practical guide
How long does it take sperm to regenerate?
Sources
- Jarow JP, Espeland MA, Lipshultz LI. Evaluation of the azoospermic patient. J Urol. 1989;142(1):62-5. PubMed
- Corona G, Minhas S, Giwercman A, et al. Sperm recovery and ICSI outcomes in men with non-obstructive azoospermia: a systematic review and meta-analysis. Hum Reprod Update. 2019;25(6):733-757. PubMed
- Minhas S, Bettocchi C, Boeri L, et al. European Association of Urology Guidelines on Male Sexual and Reproductive Health: 2021 Update on Male Infertility. Eur Urol. 2021;80(5):603-620. PubMed
- Bhasin S, Brito JP, Cunningham GR, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2018;103(5):1715-1744. PubMed
Not medical advice. Written by Eric Stephens from the research cited above; not reviewed by a doctor. If something worries you, see a GP.