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Causes Reproductive Health

Infertility in Men

Male infertility can be divided into:

  • Problems with ejaculation or erection
  • Problems within the fine, small reproductive tract ducts
  • Problems with sperm production

Problems with sperm production is by far the most common of the three, and can be detected during semen analysis. There are many causes of abnormal sperm production, including:

  • Varicocele (varicose veins)
  • Genetic problems
  • Infections
  • Exposures to heat or toxic chemicals
  • Drugs and medications
  • Hormonal imbalance

Ejaculation failure (anejaculation)

Ejaculatory failure is the inability to ejaculate. It has a variety of causes, including pelvic nerve damage from diabetes mellitus, multiple sclerosis or abdominal-pelvic surgery and spinal cord injury.

It is important to distinguish ejaculatory failure from the inability to achieve an erection, premature ejaculation and retrograde ejaculation (ejaculating into the bladder and not into the penis).

Rectal probe electroejaculation is a commonly performed technique that may enable patients to produce an ejaculate capable of achieving a pregnancy. With rectal probe, the doctor electrically stimulates the pelvic sympathetic nerves to induce a reflex ejaculation from which semen is collected.

Ejaculatory duct obstruction

Ejaculatory duct obstruction is diagnosed in approximately 10 percent of men without sperm in the ejaculate. Usually caused by stones, cysts or scar tissue blocking the prostate ducts, the condition is treated with a simple outpatient procedure that involves removing portions of the ducts. Significant improvements in semen quality occur in 70 percent of patients, which are associated with a 20 percent to 30 percent pregnancy rate.


The varicocele is defined as dilated and twisted veins within the scrotum, similar to varicose veins in the legs, and is basically a consequence of upright posture. A varicocele can be found in 42 percent of infertile men and has an unquestioned statistical association with infertility. However, 15 percent of normal, fertile men also have a varicocele.

Varicocele surgery to bind off the twisted veins will improve semen quality in roughly 67 percent of patients, with improvement most likely to be an increase in the sperms' ability to move spontaneously rather than sperm quantity. The pregnancy rate following varicocele repair is approximately 40 percent, with pregnancy occurring an average of nine months after surgery.

The varicocele remains the most correctable factor when poor semen quality is discovered, but since it is very common, the operation should be considered only if other infertility risk factors are absent.

Environment, lifestyle and fertility

Over the last several decades, concern has risen about the impact of industrialization on reproductive health. This concern stems largely from reports showing that semen quality of men in Europe and the United States has decreased over the latter half of the 20th century.

The environmental toxins most often cited as potential contributors to infertility can be organized into physical, chemical, occupational and lifestyle factors:

  • Physical factors. Hyperthermia (increased temperature), radiation and electromagnetic fields, for example, are several physical factors that have been linked to infertility in men.
  • Chemical factors. Cigarette smoking, excessive alcohol consumption, marijuana and cocaine use as well as caffeine intake may contribute to chemical causes of infertility.
  • Occupational factors. Occupational hazards such as some pesticides, industrial toxins like dioxin and polychlorinated biphenyls (PCBs), and exposure to heavy metals also may be linked to infertility.
  • Lifestyle factors. Finally, stress, nutrition and other lifestyle factors also can play a role.

UCSF Health medical specialists have reviewed this information. It is for educational purposes only and is not intended to replace the advice of your doctor or other health care provider. We encourage you to discuss any questions or concerns you may have with your provider.