Obstructive & Non-obstructive Azoospermia

Most male infertility specialists classify problems with sperm production into two main categories:

Azoospermia means the absence of sperm in the ejaculate. While the typical man has 100–300 million sperm in the ejaculate, the complete absence of any sperm in the ejaculate can obviously be the cause of a couple’s inability to conceive. To diagnose azoospermia, we perform at least two semen analyses in our andrology lab.

Obstructive Azoospermia

Obstructive azoospermia is caused when there is a plumbing problem that does not allow the sperm to get from the testis to the penis. This condition is also referred to as a post-testicular cause of azoospermia, because the sperm production in the testis is fine, but the transport system for allowing the sperm to leave the body is abnormal.


Vasectomy: The most common cause of obstructive azoospermia happens when a man has had a vasectomy. The vas deferens, which carries sperm from the testicles to the urethra during ejaculation, has been divided for contraception in the vasectomy.

Cystic fibrosis (CF): The congenital condition cycstic fibrosis is a pulmonary disease that can affect fertility. Nearly all men (95%) with cystic fibrosis (CF) do not develop all or part of the vas and epididymis on both sides (a condition called congenital bilateral absence of the vas deferens (CBAVD)). Although these transportation tubes are missing, sperm is still produced (spermatogenesis) in each testis. In fact, sperm production is normal in 90% of men with CF and CBAVD.

The exact cause of CBAVD is not known, but it is thought that the same gene mutations that cause the lung and pancreas problems with CF also cause these ducts to not form. CBAVD does not affect sexual performance or ability to make love. In fact, most people are not aware that they have CBAVD until they cannot conceive and search for care from a male-reproductive expert.

Other causes include:

  • Scarring from sexually transmitted infections.
  • Midline congenital cysts, which block the vas deferens from emptying into the urethra.
  • Narrowing of the opening of the penis from the foreskin (phimosis).

Treatment Options

Vasectomy reversal: Natural conception may be possible for the most men who have had a vasectomy through the procedures vasovasostomy and vasoepididymostomy.

Testicular sperm extraction (TESE): Another option for men who have had a vasectomy or who have another form of obstructive azoospermia is a testicular sperm extraction (TESE) procedure. During this procedure a small incision is made to expose the testicular tissue or a needle is used to aspirate the seminiferous tubules (testicular tissue) to obtain sperm.

Transurethral resection of the ejaculatory ducts (TURED): For men who have an obstruction where the vas deferens empty into the urethra at the ejaculatory ducts, a procedure called a transurethral resection of the ejaculatory ducts (TURED) can relieve this blockage and return the flow of sperm to the natural channels.

Circumcision: Narrowing of the foreskin can be treated with a circumcision.

Surgical correction for scarring: Scarring from sexual infections can often be treated endoscopically with a scope through the urethra in the operating room (with a patient under general anesthesia).

Non-Obstructive Azoospermia

Non-obstructive azoospermia is a set of disorders where there is abnormal production of sperm. All of these disorders have either decreased or no sperm production.


Non-obstructive azoospermia can be sub-divided into pretesticular and testicular causes.

Pretesticular non-obstructive azoospermia:
All of pretesticular conditions disrupt the hormones necessary for normal spermatogenesis (sperm creation).

  • Hypogonadotropic hypogonadism (a problem with the pituitary where it does not make the hormones necessary for spermatogenesis or adequate testosterone production),
  • Hypothyroidism
  • Use of certain medications
  • Elevated estradiol
  • Kallman’s syndrome
  • Certain rare types of pituitary tumors

These conditions are typically treatable through oral or injectable medications.

Testicular non-obstructive azoospermia

A testicular cause is any process that disrupts spermatogenesis inside the testicle. These causes make up the majority of non-obstructive azoospermia cases:

  • Varicoceles, or varicose veins in the scrotum, cause a disruption in spermatogenesis in the testicle (but rarely result in azoospermia)
  • Bilateral undescended testicles or cryptorchidism
  • Testicular cancer
  • Gonadotoxins (such as radiation, chemotherapy, and certain industrial chemicals that are toxic to the testes or gonads)
  • Immunologic causes, such as post-pubertal mumps orchitis (a mumps infection of the testicle in a man who has already reached puberty)
  • Sertoli-cell only syndrome (absence of sperm cells in the testis)
  • Incomplete development, where all of the sperm can only reach a certain, incomplete stage of development
  • Genetic syndromes, such as Klinefelters (presence of an extra X chromosome in a man so they have XXY instead of XY)


No matter the cause of non-obstructive azoospermia, the treatment approach is the same. We start with a semen analysis and male endocrine profile (blood work).

Medical therapy: If a man has a low bioavailable testosterone,* we typically start him on clomiphene citrate or clomid. The patient remains on this drug for four months, and we repeat another semen analysis. One in nine men will have sperm return to the ejaculate after having their testosterone brought back in the normal range through medication. Even if a man does not have sperm return to the ejaculate after taking medication, normalizing the testosterone through medication doubles the chances of finding sperm on a surgical sperm extraction procedure called microsurgical testicular sperm extraction (microTESE).

Microsurgical testicular sperm extraction (microTESE): If a man has adequate testosterone* on the initial diagnostic testing or if he has had it corrected for at least four months and remains azoospermic, we recommend microsurgical testicular sperm extraction (microTESE). Sperm is found approximately 70% of the time in the microTESE procedure.

*Note: this is very different from the total testosterone that many labs check