Hearing “no sperm were seen in your sample” is a shock, and the first question most men ask is why. The answer usually falls into one of two groups. In obstructive azoospermia the testes make sperm but a blockage stops them reaching the semen. In non-obstructive azoospermia the testes make very little or no sperm.
Telling the two apart is the single most important step, because the treatment, and the chance of having a biological child, is very different for each. This page explains how doctors make that distinction. Dr. Kalpesh Kapadia, a uro-andrologist in Ahmedabad, evaluates men with azoospermia and explains these findings in consultation.
In short: About 4 in 10 cases of azoospermia are caused by a blockage, where sperm can almost always be retrieved. The rest are due to low sperm production. A physical examination, FSH hormone level, testis size and semen volume usually show which type it is. Some causes, such as hormone deficiency or past testosterone use, can be treated.
Read about azoospermia treatment
On this page
- First, confirm it is really azoospermia
- The two main types at a glance
- Causes of obstructive azoospermia
- Causes of non-obstructive azoospermia
- How the type is worked out
- Which treatment fits which type
- Frequently asked questions
- About Dr. Kalpesh Kapadia
- Next step
- References
First, confirm it is really azoospermia
A single report showing no sperm is not enough. Guidelines recommend that the lab spins (centrifuges) the sample and examines the pellet, on at least two separate samples. Sometimes a few sperm are found, which changes the options.
It also helps to rule out problems with ejaculation itself. If very little or no fluid comes out, the semen may be going backwards into the bladder (retrograde ejaculation). A urine test after ejaculation checks for this.
The two main types at a glance
| Obstructive azoospermia | Non-obstructive azoospermia | |
|---|---|---|
| What happens | Sperm are made, but a blockage stops them | Little or no sperm is made in the testes |
| How common | About 40% of cases | About 60% of cases |
| FSH hormone | Usually normal | Often raised |
| Testis size | Usually normal | Often small |
| Semen volume | Sometimes low (if the blockage is near the prostate or the vas is absent) | Usually normal |
| Chance of finding sperm surgically | Very high | Variable; depends on the cause |
| Main treatment | Sperm retrieval for ICSI, or surgery to bypass the blockage | Treat reversible causes; Micro-TESE for ICSI |
A large study found that about 96% of men with obstructive azoospermia had an FSH below 7.6 IU/L and a testis longer than 4.6 cm, while about 89% of men with non-obstructive azoospermia had a raised FSH and smaller testes. These are guides, not rules, and some men fall in between.
Causes of obstructive azoospermia
The blockage can be anywhere along the route sperm travel, from the testis to the urethra.
- Born without the vas deferens (CBAVD): the tubes that carry sperm did not form. This is often linked to the cystic fibrosis (CFTR) gene, so genetic testing is advised.
- Infection: past epididymitis, tuberculosis or sexually transmitted infection can scar the epididymis.
- Previous surgery: vasectomy, hernia repair (especially in childhood), or scrotal surgery can block or damage the vas.
- Ejaculatory duct obstruction: a cyst or scarring near the prostate blocks the final ducts. Semen volume is usually very low.
- Unknown cause: in some men no reason is found.
Causes of non-obstructive azoospermia
Here the problem is with sperm production. Doctors sometimes divide causes into those before the testis (hormone signals) and those in the testis itself.
Hormone causes (pre-testicular), often treatable
- Low pituitary hormones (hypogonadotropic hypogonadism): the brain does not send the signal to make sperm. FSH and LH are low, not high. Hormone injections can restart sperm production in many men.
- Testosterone or anabolic steroid use: taking testosterone switches off sperm production. Stopping it, sometimes with medicines, often allows recovery over months.
- High prolactin or other hormone problems.
Testicular causes
- Genetic: Klinefelter syndrome (47,XXY) and Y-chromosome microdeletions are the most common. See genetic testing.
- Undescended testes, especially if corrected late.
- Past mumps orchitis, testicular injury or torsion.
- Chemotherapy or radiotherapy.
- Varicocele, in some men, alongside other causes.
- Unknown (idiopathic): in many men no cause is found despite full testing.
Under the microscope, the testis may show reduced production (hypospermatogenesis), production that stops partway (maturation arrest), or no sperm-making cells at all (Sertoli cell-only). These patterns are known only after a biopsy or Micro-TESE.
How the type is worked out
- History: past surgery, infections, mumps, undescended testes, cancer treatment, testosterone or steroid use, and family history.
- Examination: testis size and consistency, whether the vas deferens can be felt, the epididymis, and any varicocele.
- Semen details: volume and pH, alongside the centrifuged sperm check. Low volume with acidic semen points to a blockage near the prostate or an absent vas.
- Hormones: FSH, LH, testosterone and sometimes prolactin.
- Genetic tests: karyotype and Y-chromosome microdeletion for suspected non-obstructive cases; CFTR for an absent vas.
- Ultrasound: scrotal ultrasound, and transrectal ultrasound if ejaculatory duct obstruction is suspected.
A testicular biopsy is not usually needed just to make the diagnosis. When surgery is done, it is normally combined with sperm retrieval and freezing.
Which treatment fits which type
| Type | Treatment options |
|---|---|
| Obstructive | Sperm retrieval by PESA, TESA, MESA or TESE for ICSI; or microsurgical reconstruction (vasectomy reversal or vasoepididymostomy) in suitable men; transurethral surgery for some ejaculatory duct blocks |
| Non-obstructive, hormone cause | Hormone treatment (for example, gonadotropin injections), or stopping testosterone; sperm may return to the semen |
| Non-obstructive, testicular cause | Micro-TESE to look for small areas of sperm production, with ICSI; varicocele repair in selected men; donor sperm or adoption if sperm cannot be found |
For most couples, the treatment decision is made together with the IVF team and depends on the female partner’s age and health as well.
Frequently asked questions
What are the main causes of azoospermia?
Azoospermia is caused either by a blockage that stops sperm reaching the semen (obstructive) or by very low or absent sperm production in the testes (non-obstructive). Hormone problems, genetic conditions, past infections, surgery, undescended testes and cancer treatment are among the specific causes.
What is the difference between obstructive and non-obstructive azoospermia?
In obstructive azoospermia the testes make sperm but a blockage stops them. In non-obstructive azoospermia the testes make little or no sperm. About 40% of cases are obstructive.
How do doctors know which type I have?
Mainly from the examination, FSH hormone level, testis size and semen volume. A normal FSH with normal-sized testes suggests a blockage; a raised FSH with small testes suggests low production. Genetic tests and ultrasound add more detail.
Is obstructive azoospermia easier to treat?
Usually, yes. Sperm production is normal, so sperm can almost always be retrieved from the epididymis or testis for ICSI. Some blockages can also be bypassed with microsurgery.
Can non-obstructive azoospermia be treated?
Sometimes. If the cause is low pituitary hormones or testosterone use, treatment can restart sperm production. Otherwise Micro-TESE can often find small areas of sperm production for ICSI, though not in every man.
Can taking testosterone cause zero sperm count?
Yes. Testosterone and anabolic steroids switch off the brain signal that drives sperm production. Stopping them, sometimes with medicines, often allows sperm to return over several months.
Does a low semen volume mean a blockage?
It can. A low volume with acidic semen may mean the vas deferens is absent or the ejaculatory ducts are blocked. It can also be due to retrograde ejaculation, which a urine test after ejaculation checks.
Do I need a testicular biopsy to find the type?
Usually not. The type can normally be worked out from the examination, hormones, semen details and scans. If surgery is done, it is usually combined with sperm retrieval and freezing.
Is azoospermia always permanent?
No. Some causes, such as hormone deficiency, testosterone use or a blockage, can be treated. Even when production is very low, sperm can sometimes be found surgically.
Should my semen test be repeated if it shows no sperm?
Yes. Guidelines recommend at least two samples, each spun down (centrifuged) and examined carefully, before azoospermia is confirmed.
About Dr. Kalpesh Kapadia
Dr. Kalpesh Kapadia is a uro-andrologist in Ahmedabad, practising since 2012, who evaluates and treats male infertility, including azoospermia. He is having Mch degree in Urology..
See a doctor promptly if you have: sudden pain or swelling in a testicle, a new testicular lump, or fever with a painful, swollen scrotum. These need examination soon.
Next step
If you have been told you have azoospermia, bring all semen reports, hormone tests and any scan or genetic results to your consultation.
- Pratham IVF & Urology Clinic, Vastrapur, Ahmedabad
- Phone / WhatsApp: +91 99984 78633
- Directions on Google Maps
Medically reviewed by Dr. Kalpesh Kapadia. Last reviewed: 23 October 2026. This page is general information, not a diagnosis.