Non-obstructive causes of male infertility

Chromosomal abnormalities

Abnormal sexual chromosomes can cause low levels of testosterone. Klinefelter syndrome is the most common sexual chromosome abnormality. In some patients, this condition can cause characteristic features like long limbs, small firm testicles, and female-type hair distribution.

The treatment for this kind of infertility is to collect sperm cells directly from the testicle if possible (TESE). Sperm cells will be functional in less than half of men with Klinefelter syndrome.

Genetic defects

Low levels of sexual hormones affect male fertility. For example, Kallmann syndrome causes low levels of sexual hormones. Men with this syndrome often have low muscle mass, fatigue, infertility, erectile dysfunction, hot flashes, and enlarged breasts.

The treatment is to supplement male hormones using injections that can restore spermatogenesis completely (hormone therapy).

In addition, an increase in general health—for example, losing weight, stopping smoking, adjusting diet, and exercising regularly—may improve fertility.


When a testicle does not descend into the scrotum, the condition is called cryptorchidism. It is a birth defect and is associated with infertility. However, if a man has only one undescended testicle, his ability to father children is almost equal to that of men without cryptorchidism.

When cryptorchidism is diagnosed in early childhood, surgery to move the testicle from the abdomen into the scrotum should be performed within the first year. This can prevent later infertility and reduce the risk of testicular cancer. If an adult has an undescended testicle, surgery can optimise testosterone production.


Abnormal cell growth in the testicular tissue affects sperm production. So does cancer treatment. Testicular cancer is mostly seen in younger men and is associated with poor semen quality, cryptorchidism and in families with a history of testicular cancer.

Treatment is surgical removal of the testicle. Sometimes additional chemotherapy will be used, which can also lower semen quality. If a man wants to father children in the future, a semen sample should be collected and preserved before surgery.


Varicocele is an enlargement of the veins that drain blood from the testicles. The condition affects about 2 in 10 men and is seen in a quarter of men with abnormal semen analysis. The enlargement of these veins can be uncomfortable and can lower sperm quality. It is not fully understood how varicocele affects fertility.

Varicocele can be diagnosed easily by physical examination or by ultrasound. The treatment is surgery to close the dilated vessels and minimize blood reflux into the scrotum. Surgery can improve semen quality if no other explanation of infertility is found.

Infections in the male reproductive organs

Infections in the urethra, prostate, epididymis, and testicles are all potential causes for infertility. The infection creates antibodies that can lower semen quality. This can have a negative effect on fertility. When the location of the infection and the bacteria are identified, the treatment is mostly antibiotics.

Nevertheless, in almost half of cases, it is not possible to find a cause of infertility.