Causes

-Genetic conditions such as Klinefelter's syndrome

-Congenital absence of the vas deferens common in cystic fibrosis gene carriers

-Damage caused by seminal infections
Inflammatory processes such as epididymitis, prostatitis, parotiditis and varicocele

-Surgeries or other trauma such as inguinal hernias, testicular trauma or vasectomy

Sperm production problems may be caused by:

-Follicle-stimulating hormone (FSH)-related hormonal disturbances

-Varicocele

-Conditions of the testicles

-Genetic conditions such as deletions of the Y-chromosome

-Cancer treatments such as chemotherapy and radiation therapy