A number of factors can contribute to male infertility. These include conditions affecting sperm function, production and delivery, hormonal dysregulation, sexually transmitted diseases, general health and lifestyle factors.
• Age: Though not as marked as in women, a gradual decline in fertility is common after age 35 in men, increasing after age 42.
• Impaired shape and motility: Abnormal spermatogenesis, or sperm production, may
result in sperm that are not able to reach the
egg or to penetrate it.
• Low sperm concentration: Normal sperm
concentration in men is greater than or equal to 20 million sperm per millilitre of semen. Sperm count lower than 50 percent of this number (10 million) indicates low sperm concentration.
• Varicocele: Varicose veins in the scrotum, called varicocele, may prevent normal cooling of the testicles and lead to reduced sperm count and motility.
• Undescended testicle: This congenital condition occurs when one or both testicles fail to descend from the abdomen into the scrotum during fetal development. When the testicles are exposed to the higher internal body temperature compared to the temperature in the scrotum, sperm production may be affected.
• Testosterone deficiency (male hypogonadism): Disorders of the testicles, or conditions affecting the hypothalamus or pituitary gland in the brain, may result in low testosterone levels that impair fertility.
• Overheating the testicles: Frequent use of saunas or hot tubs can impair sperm production and lower sperm count by raising the core body temperature.
• Genetic defects: Sperm abnormalities may be genetic.
• Sexually transmitted diseases: Repeated bouts of sexually transmitted diseases, such as chlamydia and gonorrhea, can affect sperm motility.
• Sexual issues: Erectile dysfunction, premature ejaculation, painful intercourse and psychological problems can all contribute to infertility.
• Retrograde ejaculation: This occurs when ejaculate does not leave the body during orgasm but rather enters the bladder.
• Blockage of the reproductive system or anatomical irregularities: Blockage of the ejaculatory ducts or various passages through which sperm and ejaculate flow can affect fertility. Men with cystic fibrosis sometimes have a missing or blocked vas deferens, and the lack or misplacement of any part of the reproductive system will often require reconstructive surgery.
• No semen (ejaculate): Men with spinal cord injuries or diseases may not have the ability to produce the fluid required to carry the sperm from the penis into the vagina.
• Anti-sperm antibodies: These antibodies attack sperm and may be present after vasectomy or in the female's body.
• Pesticides and other chemicals: Herbicides and insecticides have been associated with reduced sperm production and testicular cancer. Lead exposure may also cause infertility.
• Malnutrition and weight management:
Deficiencies in nutrients such as vitamin C, selenium, zinc and folate may contribute to infertility. Additionally, a high body mass index is associated with impaired fertility in men and women.
• Smoking, alcohol and substance abuse: Use of cocaine or marijuana may temporarily reduce the number and quality of sperm, and smoking tobacco may lower sperm count. Alcohol has also been associated with decreased fertility.
• Cancer treatments: Cancer treatments such as radiation, chemotherapy, and in the case of testicular cancer, the removal of the testicles, can affect fertility.
• Other medical conditions: Fertility may be impaired as a result of various health conditions such as autoimmune disorders, diabetes, thyroid disease, Cushing's syndrome and anaemia.
Factors taken into account to value semen
The following factors are valued in a semen analysis:
Volume of the ejaculated matter:
Average volume per ejaculate is about 2ml. About 90% of semen volume is made up of secretions from the accessory glands, mainly the prostate and seminal vesicles.
A normal liquefied semen sample has a homogeneous, grey-opalescent appearance. It may appear less opaque if the sperm concentration is very low. A green or yellowish colour indicates seminal infection. Brown, reddish or other dark colours indicate the presence of blood (haemospermia), generally due to an inflammation or congestion in any level of the seminal path.
If the seminal liquid is thick, it can inhibit the forward movement of the sperm cells. This problem is solved by getting semen prepared for intrauterine inseminations.
The pH of semen reflects the balance between the pH values of the different accessory gland secretions, mainly the alkaline seminal vesicular secretion and the acidic prostatic secretion. pH alterations in semen indicate further alterations in the prostate or seminal vesicles. The lower reference limit for pH is 7.2.
Number of spermatozoids:
The number of spermatozoa in the ejaculate is calculated from the concentration of spermatozoa, which is measured during semen evaluation. For normal ejaculates, when the male tract is unobstructed and the abstinence time short, the total number of spermatozoa in the ejaculate is correlated with testicular volume and thus is a measure of the capability of the testes to produce spermatozoa and the patency of the male tract. Anything less than 15 million sperm per millilitre, or 39 million sperm per ejaculate, is considered low.
Sperm cell mobility:
The motility of each spermatozoon is graded as follows:
Progressive motility (PR): spermatozoa moving actively, either linearly or in a large circle, regardless of speed.
Non-progressive motility (NP): all other patterns of motility with an absence of progression, e.g. swimming in small circles, the flagellar force hardly displacing the head, or when only a flagellar beat can be observed. Immotility (IM): no movement. The lower reference limit for progressive motility (PR) is 32%. The lower reference limit for total motility (PR + NP) is 40%.
Sperm cell vitality:
It is clinically important to know whether immotile spermatozoa are alive or dead. The presence of a large proportion of vital but immotile cells may be indicative of structural defects in the flagellum; a high percentage of immotile and non-viable cells (necrozoospermia) may indicate epididymal pathology. The lower reference limit for vitality is 58%.