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Azoospermia: no sperm in semen, causes and next steps

Azoospermia means that no sperm are found in the semen, even when the whole sample is spun down and examined under a microscope. It has two broad kinds, a blockage or too little sperm production, and in many men sperm can still be found in the testicles.

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Medically reviewed by Dr Mary Davidson, Reproductive endocrinologist, checked on

A couple talking over mugs at a kitchen table, her hand on his arm, as they learn about azoospermia

This page explains what azoospermia is and what usually happens after it is found. It cannot interpret anyone's own results or say which route suits a couple: those are for the specialist team.

What is azoospermia?

The azoospermia definition is simple: no sperm in the ejaculate. Schlegel's review says the diagnosis is based on finding no sperm under the microscope after the complete semen sample has been centrifuged, spun down so that any sperm collect at the bottom (Schlegel, Reproduction, Fertility and Development, 2004). The UNC Department of Urology says a patient has azoospermia if two separate concentrated samples show no sperm, and points out that it is not the same as aspermia, where no semen at all is released (UNC Department of Urology, "Azoospermia", 2026).

The azoospermia meaning is different from a low sperm count, which means sperm are present but fewer than the reference limit; the WHO's 2021 manual puts that limit at 16 million per milliliter (WHO, "WHO laboratory manual for the examination and processing of human semen", 2021). Both are found through a semen analysis, the guide to which explains how the test is prepared for and why one result is never treated as final.

How common is azoospermia?

The figures differ by source, and no single one is definitive:

The spread reflects who was counted: men in general, men with an infertility diagnosis, or men referred to a specialist clinic.

Obstructive and non-obstructive azoospermia

Schlegel divides azoospermia into two kinds: a blockage in the reproductive tract, and production of sperm too low for any to appear in the ejaculate (Schlegel, 2004). In Jarow and colleagues' study of 133 men with azoospermia, 49 (37 in 100) had a blockage and 84 (63 in 100) had testicular failure (Jarow and colleagues, 1989).

Obstructive azoospermia

In obstructive azoospermia, sperm are made but cannot get out. Schlegel says the blockage may be present from birth, such as congenital absence of the vas deferens, the tube that carries sperm from the testicle, or acquired, from infections, vasectomy or other injuries to the reproductive tract (Schlegel, 2004). In the 1989 study, a third of the men with a blockage had the vas deferens missing on both sides (Jarow and colleagues, 1989). Schlegel notes that when a man has a congenital blockage, his female partner should be tested for cystic fibrosis gene changes, because such men have a high chance of carrying one (Schlegel, 2004).

Non-obstructive azoospermia

In non obstructive azoospermia, the testicles do not make enough sperm. UNC Urology splits it in two (UNC Department of Urology, 2026):

  • Pre-testicular: the testicles are normal but are not stimulated properly, because of a problem with the hypothalamus or pituitary gland in the brain and the hormones they control.
  • Testicular: the testicles themselves cannot produce sperm, from a condition present from birth or one acquired later.

Cerván-Martín and colleagues put non-obstructive azoospermia at around 1 in 100 men and 10 in 100 infertile men, and say known genetic causes explain only around a quarter of azoospermia cases, with the rest unexplained (Cerván-Martín and colleagues, Journal of Clinical Medicine, 2020).

What causes azoospermia?

Azoospermia causes are many. UNC Urology lists them by type (UNC Department of Urology, 2026):

  • Pre-testicular: poor nutrition, some medicines such as certain chemotherapies and narcotics, pituitary tumors, trauma, low testosterone, other pituitary disorders, and the use of testosterone replacement therapy or anabolic steroids, which suppress the body's own testosterone and so sperm production.
  • Testicular, from birth: undescended testicles (cryptorchidism), Klinefelter syndrome, Sertoli-cell-only syndrome, chromosome abnormalities and deletions on the Y chromosome.
  • Testicular, acquired: infections such as mumps orchitis, exposure to pesticides and chemicals, injury, cancer and its treatment, and radiation; it may also be associated with a varicocele.
  • Obstructive: blockage of the tubes, from birth or from infection, vasectomy or surgery (Schlegel, 2004).

Witherspoon and colleagues describe Y chromosome microdeletions as the second most commonly identified genetic cause of male infertility after Klinefelter syndrome (Witherspoon and colleagues, Translational Andrology and Urology, 2021). The NHS adds that chemotherapy can sometimes severely reduce sperm production, that long-term misuse of anabolic steroids can reduce sperm count, and that a vasectomy can be reversed but reversals are not usually successful (NHS, "Infertility: causes", 2023). The wider causes of male infertility are covered in the guide to male fertility.

Azoospermia symptoms

There are usually none beyond not conceiving. Cleveland Clinic says people usually do not realize they have the condition until they try to conceive without success, and that some have symptoms from the underlying cause, such as low sex drive from a hormone imbalance or a lump from an infection (Cleveland Clinic, 2023). The NHS advises seeing a GP if you and your partner have not conceived after a year of regular sex without contraception, or 6 months if your partner is 36 or over (NHS, "Low sperm count", 2024). The US and UK timings for both partners are compared in when to see a doctor about fertility.

How azoospermia is diagnosed

  1. Repeat semen analysis. No sperm in two separate centrifuged samples (UNC Department of Urology, 2026; Schlegel, 2004).
  2. History, examination and hormones. Schlegel says history, physical examination and hormone tests for FSH and testosterone together predict whether azoospermia is obstructive or non-obstructive in more than 90 in 100 cases (Schlegel, 2004). In the 1989 study, testicle size, semen volume and FSH differed significantly between men with a blockage and men with testicular failure (Jarow and colleagues, 1989).
  3. Genetic tests. Testing for Y chromosome microdeletions has become standard practice in men with azoospermia (Witherspoon and colleagues, 2021), and Schlegel says Y microdeletion analysis and karyotype testing give information about the outlook in non-obstructive azoospermia (Schlegel, 2004).
  4. Testicular biopsy. Schlegel and Jarow and colleagues describe biopsy as the test that defines the type in full (Schlegel, 2004; Jarow and colleagues, 1989).

In the UK, the NHS route runs from the GP, who arranges the first tests, to a specialist after a second abnormal semen analysis (NHS, "Low sperm count", 2024).

What happens next

Azoospermia treatment depends on the cause, and the sources describe several routes. None is recommended here; which, if any, suits a couple is decided with their specialist team.

  • Repairing a blockage. Schlegel says acquired blockages may be treated with microsurgical reconstruction or by opening the ejaculatory ducts, depending on where the blockage is (Schlegel, 2004).
  • Treating a hormonal cause. UNC Urology says pre-testicular azoospermia often responds to hormone treatment supervised by a physician (UNC Department of Urology, 2026).
  • Stopping what caused it. UNC Urology says azoospermia from toxic exposures such as chemotherapy drugs may resolve with time after they stop (UNC Department of Urology, 2026); testosterone therapy and anabolic steroids are among the causes it lists.
  • Sperm retrieval with ICSI. Sperm can be taken directly from the testicle or the tubes, for example by testicular sperm extraction (TESE) or microdissection TESE (micro-TESE), and injected into eggs in the laboratory by intracytoplasmic sperm injection (ICSI), part of IVF. Schlegel reports that after any treatable factors are dealt with, retrieval from the testis may succeed in 30 to 70 in 100 men with non-obstructive azoospermia, and that centers report pregnancy rates of 20 to 50 in 100 once sperm are found (Schlegel, 2004). The 2025 review calls micro-TESE the main approach in non-obstructive azoospermia (Cakiroglu and colleagues, 2025). These are ranges reported by different centers, not anyone's personal chance.
  • Donor sperm. The NHS names sperm from a donor among the treatments when a sperm count is very low (NHS, "Low sperm count", 2024), and UNC Urology mentions donor sperm or adoption when retrieval is not possible (UNC Department of Urology, 2026).

UNC Urology notes a drawback of retrieval with ICSI in some genetic causes: the same condition can be passed on to sons, so couples are counseled about that risk (UNC Department of Urology, 2026). The last step of IVF, putting an embryo in the womb, is described in the guide to embryo transfer.

Supplements and lifestyle changes are often promoted for azoospermia. None of the sources on this page presents a supplement as a treatment for it; what the evidence says about habits and sperm generally is in the guide to sperm health.

This guide is information, not a diagnosis or a recommendation of treatment, and it is no substitute for your own clinician. See the medical disclaimer.

Sources

  1. Schlegel PN. Causes of azoospermia and their management. Reproduction, Fertility and Development 16(5): 561-572, 2004.
  2. Jarow JP, Espeland MA, Lipshultz LI. Evaluation of the azoospermic patient. Journal of Urology 142(1): 62-65, 1989.
  3. Cakiroglu Y, Gudelci T, Tiras B. Intratesticular autologous platelet-rich plasma injection in couples with nonobstructive azoospermia: a narrative review. Fertility and Sterility 124(3): 417-425, 2025.
  4. Cerván-Martín M, Castilla JA, Palomino-Morales RJ, Carmona FD. Genetic landscape of nonobstructive azoospermia and new perspectives for the clinic. Journal of Clinical Medicine 9(2): 300, 2020.
  5. Witherspoon L, Dergham A, Flannigan R. Y-microdeletions: a review of the genetic basis for this common cause of male infertility. Translational Andrology and Urology 10(3): 1383-1390, 2021.
  6. UNC Department of Urology. Azoospermia. University of North Carolina School of Medicine, 2026.
  7. NHS. Infertility: causes. nhs.uk, 2023.
  8. NHS. Low sperm count. nhs.uk, 2024.
  9. World Health Organization. WHO laboratory manual for the examination and processing of human semen, sixth edition. WHO, 2021.
  10. Cleveland Clinic. Azoospermia. my.clevelandclinic.org, 2023.

Frequently asked questions

Can you have a baby with azoospermia?

Often, yes, though usually with treatment. Sperm can sometimes be retrieved from the testicles or the tubes and used with ICSI, a form of IVF, and some blockages can be repaired. Where no sperm can be found, donor sperm is another route. The chances depend on the cause.

Can azoospermia be corrected?

Sometimes. Some blockages can be repaired surgically, some hormonal causes respond to treatment, and azoospermia caused by medicines such as testosterone or by chemotherapy may resolve after they stop, according to the sources on this page. Other causes, such as some genetic ones, cannot be corrected.

What is the main cause of azoospermia?

In one study of 133 men, 63 in 100 had failure of the testicles to make enough sperm and 37 in 100 had a blockage (Jarow 1989). Many causes sit within those groups, from hormone problems and genetic conditions to infections, cancer treatment and vasectomy.

Is azoospermia the same as a low sperm count?

No. A low sperm count means fewer sperm than the reference limit, which the WHO 2021 manual puts at 16 million per milliliter. Azoospermia means none are found at all, even after the sample is concentrated.

My partner has azoospermia, but I got pregnant. How?

This page cannot answer for any one couple. What the sources say is that the diagnosis rests on finding no sperm in concentrated samples, usually two of them, and that semen results vary between samples. A question like this is for the specialist who made the diagnosis.