Six Causes of Male Infertility and How Doctors Diagnose 70% of Cases

Male infertility is found to be the underlying cause of a couple's inability to get pregnant in about 30 percent of cases. Infertility is traditionally defined in the medical field as the inability to get pregnant after one year of trying without birth control. This condition affects 15 to 20 percent of couples and is complicated by the fact that it can be caused by both male infertility and female infertility or reproductive difficulties.

Approximately one out of every 25 men are infertile, and 90 percent of those cases of male infertility are due to low sperm count, poor semen quality, or both. Some studies have found that, even without treatment, 33 percent of infertile couples are still able to conceive within four years.

Causes of Male Infertility

In general, male infertility is caused by difficulty with one or more of the following:

  • Sperm formation: Problems with sperm production can lead to sperm that are abnormally shaped or have difficulty moving, both of which can reduce the ability of the sperm to fertilize a woman’s egg.

  • Sperm concentration: A low sperm count, or the absence of sperm (azoospermia) in the ejaculate, reduces the a woman's chance of getting pregnant.This can be caused by either a problem with sperm production or a blockage.

  • Transportation: A blockage in the tubes that carry sperm (either the epididymis or the ejaculatory duct) can prevent sperm from reaching the ejaculate.

These difficulties can stem from several underlying causes, including:

  • Varicocele (enlarged veins in the scrotum that warm the testicles and reduce the production of sperm)
  • An immune reaction (sperm antibodies) that attacks the sperm
  • Infections, such as those in the tubes that carry sperm
  • Exposure to certain pesticides and chemicals
  • Retrograde ejaculation (when ejaculate ends up in the bladder instead of leaving the body)
  • Lifestyle choices, such as obesity, excessive alcohol drinking, smoking tobacco, or illegal drug use

In addition, sperm concentration decreases as men age, starting around age 35. Older men may be just as fertile as younger men, although it can take longer for them to get a woman pregnant.

Diagnosis of Male Infertility

Because a couple’s infertility can involve either the man, the woman, or both, a doctor may request an examination of the patient's partner. Around 70 percent of cases of male infertility can be diagnosed with the following:

  • Medical history: This includes sexual and reproductive history, possible exposure to chemicals, current and past medications, infections of the reproductive system (including sexually transmitted diseases), injury or surgery that affected the pelvis, groin or genitals, and family history of infertility.

  • Physical exam: This assesses the size and shape of the man's testicles, indications of a varicocele, and potentially a rectal exam.

  • Hormone analysis: Hormones (such as FSH, LH, testosterone and prolactin) play an important part in the production of sperm, and imbalances can cause infertility.

  • Semen analysis: This includes sperm count, concentration, and quality. Additionally, this test assesses the volume and consistency of semen, as well as the presence of red and white blood cells and bacteria.

In some cases, diagnosis may also involve an ultrasound to examine the size and shape of the testicles, to determine whether a varicocele is present, and to check for problems with the ejaculatory duct or seminal vesicles. When a man has a very low sperm count, a doctor may also request genetic testing to look for inheritable causes that can affect fertility, such as cystic fibrosis (CF) and problems with the Y chromosome.

Treatment for Male Infertility

Treatment of male infertility depends upon the underlying cause, and can include medical therapy and surgery.


Coburn, M. (2013). Urologic surgery. Sabiston Textbook of Surgery, 19th ed.

Sabanegh E, & Agarwal A. (2011). Male infertility. Campbell-Walsh Urology, 10th ed.

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