The main sign of male infertility is the inability to conceive a child. There may be no other obvious signs or symptoms. In some cases, however, an underlying problem such as an inherited disorder, a hormonal imbalance, dilated veins around the testicle or a condition that blocks the passage of sperm causes signs and symptoms.
Although most men with male infertility do not notice symptoms other than the inability to conceive a child, signs and symptoms associated with male infertility include:

• Problems with sexual function — for example, difficulty with ejaculation or small volumes of fluid ejaculated, reduced sexual desire, or difficulty maintaining an erection (erectile dysfunction)
• Pain, swelling or a lump in the testicle area
• Recurrent respiratory infections
• Inability to smell
• Decreased facial or body hair or other signs of a chromosomal or hormonal abnormality
• A lower than normal sperm count (fewer than 15 million sperm per milliliter of semen or a total sperm count of less than 39 million per ejaculate)

Medical Causes
Problems with male fertility can be caused by a number of health issues and medical treatments. Some of these include:
1) Varicocele
A varicocele is a swelling of the veins that drain the testicle. It's the most common reversible cause of male infertility. Although the exact reason that varicoceles cause infertility is unknown, it may be related to abnormal testicular temperature regulation. Varicoceles result in reduced quality of the sperm. Treating the varicocele can improve sperm numbers and function, and may potentially improve outcomes when using assisted reproductive techniques such as in vitro fertilization.
2) Infection
Some infections can interfere with sperm production or sperm health or can cause scarring that blocks the passage of sperm. These include inflammation of the epididymis (epididymitis) or testicles (orchitis) and some sexually transmitted infections, including gonorrhea or HIV. Although some infections can result in permanent testicular damage, most often sperm can still be retrieved.
3) Hormone imbalances
Infertility can result from disorders of the testicles themselves or an abnormality affecting other hormonal systems including the hypothalamus, pituitary, thyroid and adrenal glands. Low testosterone (male hypogonadism) and other hormonal problems have a number of possible underlying causes.
4) Antibodies that attack sperm
Anti-sperm antibodies are immune system cells that mistakenly identify sperm as harmful invaders and attempt to eliminate them.

Environmental Causes
Over exposure to certain environmental elements such as heat, toxins and chemicals can reduce sperm production or sperm function. Specific causes include:
1) Industrial chemicals
Extended exposure to benzenes, toluene, xylene, pesticides, herbicides, organic solvents, painting materials and lead may contribute to low sperm counts.
2) Heavy metal exposure
Exposure to lead or other heavy metals also may cause infertility.
3) Overheating the testicles
Elevated temperatures impair sperm production and function. Although studies are limited and are inconclusive, frequent use of saunas or hot tubs may temporarily impair your sperm count.
Sitting for long periods, wearing tight clothing or working on a laptop computer for long stretches of time also may increase the temperature in your scrotum and may slightly reduce sperm production.

Health, lifestyle and other causes
Some other causes of male infertility include:

• Drug use
• Alcohol use
• Tobacco smoking
• Emotional stress
• Depression
• Obesity

An exact cause of infertility can't be identified. Even if an exact cause isn't clear, your doctor might be able to recommend treatments or procedures that will result in conception.
Treatments for male infertility include:
Surgery For example, a varicocele can often be surgically corrected or an obstructed vas deferens repaired. Prior vasectomies can be reversed. In cases where no sperm are present in the ejaculate, sperm can often be retrieved directly from the testicles or epididymis using sperm-retrieval techniques.
Treating infections Antibiotic treatment might cure an infection of the reproductive tract, but doesn't always restore fertility.
Hormone treatments and medications Your doctor might recommend hormone replacement or medications in cases where infertility is caused by high or low levels of certain hormones or problems with the way the body uses hormones.
Assisted reproductive technology (ART) ART treatments involve obtaining sperm through normal ejaculation, surgical extraction or from donor individuals, depending on your specific case and wishes. The sperm are then inserted into the female genital tract, or used to perform in vitro fertilization or intracytoplasmic sperm injection.