The oligozoospermia is a male diagnosis defined as a low sperm in the ejaculate whilst the sexual and ejaculation function is normal. This diagnosis belongs to a group of diagnosis of abnormal sperm quality (Pic. 1).

Sperm concentration (or sperm count) is the number of sperm in the ejaculate. The World Health Organization (WHO) now considers a low sperm count is less than 15 million sperm / ml.

It is important to say, that the sperm count is a relatively sensitive measure of overall health. Oligozoospermia can be the result of many factors; depending on the causing factors, oligozoospermia may be permanent or reversible. Chronic stress and sleeping disorders, work and emotional issues as well as unhealthy lifestyle, obesity, use of alcohol, tobacco or recreational drugs can all lower the sperm count at otherwise healthy men. Generally said, these effects are reversible upon recovery. Notably, pills to improve man erection, such as Viagra, Levitra and Cialis do not cause low sperm count. 

Except health issues explained above, the causes of oligozoospermia include:

  • An obstruction of the normal flow of sperm – due to such conditions as testicular trauma or vasectomy (surgical procedure for male sterilization). It may also result from scarring due to surgery on the male reproductive system, infection or sexually transmitted disease.
  • Decrease of sperm production – due to varicoceles (abnormal enlargement of small veins in scrotum), hormonal disorders or diseases of the testicles.
  • According to some researches, a low sperm count can be an indicator of general medical problem or a genetic condition. In few percentages of cases, low sperm count may be due to hormonal inbalances from prolactinoma, rare usually benign pituitary tumor (can be treated with medication). On the other hand, one of the most common causes of low sperm count is a varicocele (as mentioned above). 

Increasingly, the genetic abnormalities are being found in men with severe oligozoospermia. These genetic abnormalities consist in missing regions (genes) on the Y chromosome. This abnormality is called microdeletions. These microdeletions are passed on to a male offspring. Other genetic abnormalities include conditions such as Klinefelter syndrome (XXY) or exchange of genetic material in non-sex chromosomes and all these abnormalities are detected by blood test.

Oligozoospermia is usually classified into 3 categories according to level of the low sperm count – mild, moderate and severe oligozoospermia. Table 1 shows how low sperm count is described, also in comparison with other diagnosis - cryptozoospermia and azoospermia.

Associated diseases

  • azoospermia
  • asthenospermia
  • cryptozoospermia
  • teratozoospermia


  • infertility

Risk factors

  • age (the semen parameters, such as sperm count spontaneously decrease between the ages of 22 and 80 years)
  • obesity
  • heart disease
  • diabetes
  • infections
  • stress
  • smoking
  • medications (also antiandrogens, sulfa agents, Ca+ channel blockers, alpha blockers)
  • anabolic steroid use
  • testicular trauma
  • sexually transmitted disease
  • varicocele
  • genetic abnormalities at the Y chromosome - microdeletions
  • abnormal set of chromosomes - Klinefelter syndrome
  • ejaculatory duct obstruction
  • benign prostatic hyperplasia
  • prolactinoma – benign pituitary tumor
  • hypogonadism due to various causes
  • cryptorchidism
  • hydrocele
  • mumps
  • malaria
  • multiple sclerosis
  • industrial toxins: Dioxin, PCBs (polychlorinated biphenyl), bisphenol A

Oligozoospermia is the abnormality of sperm count in semen. Depending upon the sperm count, the chance of conception can be lower than at a healthy man. The smaller sperm count is, the chance to conceive decreases. However, chances are very good if a female partner is fertile. 

Besides, exclusion of other abnormal characteristics of sperm cells, such as shape or motility is necessary, and thus the combination of oligozoospermia with asthenozoospermia or teratozoospermia. The combination of oligozoospermia with other diagnosis of abnormal characteristics of sperm cells may even more decrease the chances for successful conception.

  • avoiding drugs, alcohol, smoking
  • keeping healthy lifestyle
  • prevention of sexually transmitted diseases

There are no specific symptoms of oligozoospermia. The patient usually gets to know the diagnosis when having problems with conception.

The secondary symptoms can vary in dependence on underlying condition such as healthy lifestyle, level of stress, anxiety or weakened immune system due to infection or illness. At some risk factors we can observe more symptoms such as those:

  • at sexually transmitted diseases – burning with urination, testicular pain
  • at varicocele – dilated veins in the scrotum or swelling of the scrotum

A conservative regime can improve a semen quality after a transient illness or due to secondary factors. It is recommended to reduce the level of stress, achieve the optimal weight and the attention ought to be paid to healthy lifestyle. It is recommended to limit or avoid the alcohol intake as well as smoking.

Chinese medicine

Several studies have proven that Traditional Chinese herb medicine may increase sperm parameters and thus to increase the sperm concentration besides the others. Usually, the treatment of Chinese herb medicine was combined by vitamin E. It has been also proven that acupuncture, as a ancient form of Chinese medicine may notably increase sperm quality.

The sperm count may be increased by several treatments, depending upon the patient health and other complications.


Hormonal therapy
Clinical trials have shown that hormonal therapy has no value at oligozoospermia. However, rarely the severe oligozoospermia is due to isolated deficiency of FSH (follicle-stimulating hormone), which responds to replacement therapy.

Low levels of free radicals (ROS) can initiate sperm activation, thus the ROS levels are regulated by natural antioxidants in seminal plasma: vitamin C and vitamin E, zinc, catalase, superoxide dismutase, glutathione peroxidase.

Surgical therapy

Surgical therapy of varicoceles
Varicoceles are one of the most frequent specified diagnoses at oligozoospermia. They occur in about 20 % of fertile men but were found in 40 % of subfertile men with oligozoospermia. In oligozoospermic men with varicoceles there are often more additional features appeared such as gland infection, unilateral obstruction or anti-sperm antibodies.

Varicocele surgery contains supra-inguinal ligation, open ligation is usually reserved for 5 % of recurrences that occur. Bilateral varicocele may be treated laparoscopically. Most couples may prefer assisted conception however obliteration of internal spermatic veins by interventional radiology is also often accepted (especially if the female partner is younger than 30 years).

Assisted reproductive technology (ART) is the technology used to achieve pregnancy in procedures such as fertility medication, artificial insemination, in vitro fertilization and surrogacy. It is reproductive technology used primarily for infertility treatments, and is also known as fertility treatment. It mainly belongs to the field of reproductive endocrinology and infertility, and may also include intracytoplasmic sperm injection (ICSI) and cryopreservation. Some forms of ART are also used with regard to fertile couples for genetic reasons (preimplantation genetic diagnosis). ART is also used for couples who are discordant for certain communicable diseases; for example, HIV to reduce the risk of infection when a pregnancy is desired.

If conservative medical treatments fail to achieve a full term pregnancy, the physician may suggest the patient undergo in vitro fertilization (IVF). IVF and ART generally start with stimulating the ovaries to increase egg production. Most fertility medications are agents that stimulate the development of follicles in the ovary. Examples are gonadotropins and gonadotropin releasing hormone. After stimulation, the physician surgically extracts one or more eggs from the ovary, and unites them with sperm in a laboratory setting, with the intent of producing one or more embryos. Fertilization takes place outside the body, and the fertilized egg is reinserted into the woman's reproductive tract, in a procedure called embryo transfer.

Intracytoplasmic sperm injection (ICSI) is beneficial in the case of male factor infertility where sperm counts are very low or failed fertilization occurred with previous IVF attempt(s). The ICSI procedure involves a single sperm carefully injected into the center of an egg using a microneedle. With ICSI, only one sperm per egg is needed. Without ICSI, you need between 50,000 and 100,000.

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