In 20% to 30% of cases, a male cause is found during the couple’s infertility assessment. This male infertility is relatively easy to diagnose thanks to the spermogram which will reveal one or more spermatic abnormalities. On the other hand, there are multiple possible causes for this alteration of the sperm.

In the vast majority of cases, male infertility is linked to a sperm abnormality that the spermogram, carried out systematically during the infertility assessment, will identify. Depending on the altered sperm parameters, different sperm abnormalities can be distinguished which may be present in isolation or in combination:

• azoospermia: the complete absence of sperm in the semen;
• oligozoospermia (or oligospermia): an insufficient number of sperm;
• asthenozoospermia (or asthenospermia): insufficiently mobile sperm;
• teratozoospermia (or teratospermia): an excessive proportion of spermatozoa with morphological abnormalities;
• oligo-astheno-teratozoospermia (OATS);
• necrozoospermia: a high percentage of dead sperm.

These sperm abnormalities can be caused by hormonal insufficiency or an organic defect in the testes which will alter the process of spermatogenesis. Sometimes the semen is of good quality but a problem with the excretory ducts (epididymis, vas deferens or ejaculatory ducts) prevents it from being ejaculated.

Infertility may be due to hypogonadism, i.e. insufficient secretion of FSH and LH which regulate spermatogenesis, resulting in so-called secretory azoospermia. This hypogonadism can have different origins:

• certain birth defects such as Klinefelter syndrome which affects 1 in 600 boys (1). Due to the presence of an additional X chromosome, this syndrome is present from birth but often the manifestations are not visible until puberty, with a great variability of expression but a constant sign, infertility. Kallmann-Morsier syndrome also causes hypogonadism.
• a pituitary tumor may alter the functioning of the hypothalamic-pituitary axis responsible for the secretion of gonadotropins (KH and FSH);
• a general illness such as diabetes or hyperthyroidism can have an impact on the hormonal chain and therefore spermatogenesis.

Different pathologies can affect the proper functioning of the testicles:

The cryptorchidie

It’s a birth defect. Commonly called “undescended testicle”, it corresponds to the cessation of migration of the testicle during fetal life. In 80% of cases, it concerns only one testicle; in 20% of cases, it affects both sides (2) and therefore has an impact on fertility. For spermatogenesis to take place correctly, the testes must be located at a temperature of 33 to 34 ° C, in the bursa, and not inside the body at 37 ° C.

The varicocèle

It affects 15% of men, is characterized by the dilation of a vein in the spermatic cord. When it is large in size, this varicose vein can interfere with the development and function of the testicle. The links between varicocele and infertility are not obvious but the figures suggest that they exist: 35% of men affected by primary infertility have varicocele, 80% in the case of secondary infertility, against only 15 % in the general population (3).

Cystic fibrosis

This genetic disease, which affects 1 in 4 newborns (500), is mainly known for its respiratory and digestive symptoms, but it also has major repercussions on the reproductive organs (absence or anomaly of the vas deferens) and causes infertility in 4%. men affected.

Sometimes it’s a infection which caused organic lesions:

• an orchitis (inflammation of the testis) following an infection or a viral disease such as mumps (mumps orchitis) may have damaged the testes with an impact on spermatogenesis;
• epididymitis (inflammation of the epididymis), which most often results from a sexually transmitted infection (Chlamydia trachomatis et Neisseria gonorrhoeae) or Enterobacteriaceae (Escherichia coli) may have damaged epididydime. So even if the sperm production is correct, it cannot be evacuated.

Treatment (radiotherapy, chemotherapy) or surgery can also cause irreversible damage to the testes or the vas deferens.

Finally retrograde ejaculation (semen is ejaculated into the bladder) can lead to infertility. It may be due to:

• taking certain medications;
• surgery to the prostate, bladder or spine.

Apart from any pathology, there has been a decline in the quality of sperm in men for 50 years. We do not yet know all the mechanisms involved but various parameters are suspected of altering the fertilizing power of sperm:

• the tobacco ;
• the alcohol ;
• Drugs ;
• intensive sport;
• the stress ;
• an unbalanced diet;
• exposure to certain environmental pollutants.

Different studies have experimentally shown that fetal exposure to phthalates, chemicals used in many objects to soften plastics, can destroy the Leydig cells that produce sperm. A study of the insert (5) published in 2013 in the journal Plos One has experimentally demonstrated that low concentrations of bisphenol A are sufficient to act negatively on the testis. Pesticides are also strongly suspected of altering sperm as evidenced by this 2015 published study (6) which shows that men who consume the most fruits and vegetables loaded with pesticides have lower quality sperm, with a lower sperm count. 49% lower and 32% lower normal-shaped sperm percentage.