What is Male Infertility, Causes  and Diagnosis?
Generally, infertility is defined as one year of regular unprotected intercourse without conception. Male infertility means that a man has a problem with his reproductive system.
What are causes of infertility?
The cause of infertility is divided into Female Factor, Male Factor and Unexplained Infertility. Sometimes after a precise medical examination, the husband and wife may be completely healthy, but they will not be fertilized for unknown reasons, which is explained by Unexplained Infertility.
Today, many lifestyle factors such as the age at which to start a family, nutrition, weight, exercise, psychological stress, environmental and occupational exposures can have substantial effects on fertility. 
Causes of male factor:
Problems with male fertility can be caused by a number of health issues and medical treatments: 
    Disruption of testicular or ejaculatory function caused by man.
    Varicocele, a condition in which the veins within a man’s testicle are enlarged. Although there are often no symptoms, varicoceles may affect the number or shape of the sperm.
    Undescended testicles
    Hormonal imbalances
    Pelvic and inguinal surgeries
    Trauma to the testes may affect sperm production and result in lower number of sperms
    Heavy alcohol use, smoking, anabolic steroid use, illicit drug and some medication use.
    Cancer treatment involving certain types of chemotherapy, radiation, or surgery to remove one or both testicles
    Medical conditions such as diabetes, cystic fibrosis, certain types of autoimmune disorders, and certain types of infections may cause testicular failure
    Obesity
    Occupational and environmental disruptors

What are the Tests for Infertility Diagnosis in Men?
Infertility in men can be caused by different factors and is typically evaluated by:
•    Medical History: Asking questions about any inherited condition, past medical history, family history of infertility or birth defects, medications used, sexual habits, prior surgeries or injuries that could affect fertility. 
•    Physical Examination: A physical examination to evaluate your genitals.
•    Laboratory Tests
    Semen Analysis is performed, the number of sperm (concentration), motility (movement), and morphology (shape) are assessed by a specialist. A slightly abnormal semen analysis does not mean that a man is necessarily infertile and also normal semen does not guarantee his fertility. Instead, a semen analyses helps to determine if and how male factors are contributing to couple’s infertility. 
Depending on your situation, your testing may include:
•    Hormonal Test: Hormonal tests evaluate levels of testosterone and FSH (follicle-stimulating hormone) to determine the overall balance of the hormonal system and specific state of sperm production. Serum LH and prolactin are other hormonal tests that may be done if initial testing indicates the need for them.
•    Genetic Testing: To rule out underlying mutations in one or more gene regions of the Y chromosome, or to test for cystic fibrosis in men missing the vas deferens. Genetic testing might be ordered to diagnose various congenital or inherited syndromes. An analysis of the karyotype can provide clues in certain situations such as: non-obstructive azoospermia, severe oligospermia cc: RPL, RTF, ….
•    Blood Tests: These can indicate the presence of an infection.
•    Testicular Biopsy: To determine if sperm production is impaired or a blockage exists.
•    Postcoital Urinalysis To determine if obstruction or retrograde ejaculation exists.
•    DNA Fragmentation Index (DFI): As a measure of sperm quality and fertility.
•    Scrotal Ultrasound: Can check the vascular condition of the testicles and report the presence or absence of varicocele and the grading of varicocele.
•    Transrectal Ultrasound: Check prostate and look for blockages of the tubes that carry semen.