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Infertility: Problems With the Man's Reproductive System - Topic Overview

The most common cause of male infertility is low sperm count. Absence of sperm in the semen is less common, affecting only 1% of all men and 10% to 15% of infertile men.¹

Causes of sperm count problems include:

Hormonal problems in the testicles or pituitary gland. The pituitary gland releases hormones that stimulate the testicles to produce testosterone.
Testicular injury or failure, either present at birth (congenital) or associated with radiation or toxic chemical exposure.
Cancer treatment with certain kinds of chemotherapy or radiation.
Antibodies that attack sperm and that also may be present in semen. Sperm antibodies sometimes develop when a man's sperm has been exposed to his immune system (outside of the testicles). This may happen after a vasectomy, an infection, or an injury to the testicles.²
Drug use (some prescription medications, and marijuana and tobacco use).
Structural problems. These include:
- A varicocele in the testicles.
- Blocked ejaculation due to a surgical vasectomy.
- Absence of a vas deferens (a birth defect that may be associated with the cystic fibrosis genes).
- Retrograde ejaculation (the ejaculation of semen into the bladder rather than out through the penis).
Chromosomal problems (such as Klinefelter syndrome).
Genetic problems.

See an illustration of the male reproductive system .

WebMD Medical Reference from Healthwise

Last Updated: March 19, 2010

This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.