Oligospermia is a spermatic abnormality characterized by an abnormally low amount of spermatozoa. Depending on its degree and other spermatic anomalies possibly associated, it can have an impact on the fertility of the man and be responsible for difficulties to have a baby.
What is oligospermia?
Oligospermia, or oligozoospermia, is a sperm abnormality characterized by a lower sperm concentration than normal. The fertility of the man can be diminished, and the couple can then meet difficulties to conceive. However, if sperm concentration is an important parameter, it is not a discriminating factor for human fertility, unlike azoospermia (total absence of spermatozoa). In theory, just a sperm is enough for fertilization to take place.
Oligospermia can exist in isolation, but it is often associated with other spermatic abnormalities: asthenospermia (insufficient mobility of spermatozoa) and teratozoospermia (too many abnormally shaped spermatozoa). This is called oligo-astheno-teratozoospermia (OATS). The impact on fertility is more important in this case, because the fertilizing power of spermatozoa (already fewer) is altered because of their morphological defect and reduced mobility.
The causes of Oligospermia
As with all spermatic abnormalities, different causes can cause oligospermia because many factors can alter the process of spermatogenesis:
- an infection that caused obstruction of the vas deferens or inflammation of the seminal vesicles;
- a lack of hormonal stimulation (extreme oligospermia);
- lesion of a testicle following infection (orchitis), surgery, testicular torsion that is poorly managed;
- a genetic abnormality (severe oligospermia);
- a varicocele;
- some drug treatments (chemotherapy, anabolic steroids, hypertension drugs, gout medication, interferon prescribed in certain viral diseases …);
- exposure to certain toxic substances: alcohol, drugs, tobacco (including for in utero exposure), and presumably some environmental pollutants (phthalates, pesticides);
- exposure of the testicles to high temperature in certain risky occupations;
- General disease (liver, kidney).
Depending on its origin, oligospermia may be transient or irreversible. But often oligospermia remains of unknown origin.
Symptoms of Oligospermia
Oligospermia is not manifested by any symptoms, except a difficulty to conceive for the couple.
The diagnosis of Oligospermia
Oligospermia is diagnosed in spermograms routinely performed in men during an infertility assessment. During this sperm analysis, different parameters are evaluated:
- the pH of the sperm;
- the volume of the ejaculate;
- the concentration of spermatozoa;
- the mobility of spermatozoa;
- the morphology of spermatozoa;
- The vitality of the spermatozoa.
The results are compared to the threshold values defined by WHOM. If sperm concentration is less than 15 million / ml ejaculate or 39 million / ejaculate, oligospermia is suspected.
A second or third spermogram will be performed at 3-month intervals (a spermatogenic cycle lasting 74 days) to confirm the diagnosis. The number of ejaculated spermatozoa can indeed vary considerably from one ejaculation to another depending on different factors (duration of abstinence before collection, fatigue, infection, stress, exposure to toxic substances, etc.), and in some cases, oligospermia may be transient.
Depending on the results, different degrees of oligospermia can be distinguished:
- light oligospermia: between 5 and 14 million spermatozoa / ml;
- moderate oligospermia: between 1 and 5 million spermatozoa / ml;
- Severe oligospermia: concentration less than 1 million / ml.
Other tests may be prescribed to better assess the impact of oligospermia on human fertility, identify the cause of this oligospermia and guide the management of:
- the migration-survival test (TMS) or selection-survival test, usually performed after the spermogram and systematically before any MPA technique, allows, after centrifugation of the sperm that will select the “best sperm”, to evaluate their number , their mobility and their survival at 24 hours and thus to estimate the number of spermatozoa able, finally, to fertilize an oocyte;
- a hormonal assessment to detect a possible hormonal insufficiency;
- an ultrasound of the testicles,
Treatment and prevention of Oligospermia
The management of oligospermia depends on its cause, if it is found.
If a toxic cause is suspected (consumption of alcohol, drugs …), the man will have to limit his exposure to the toxic one. A spermogram will be performed again to control the count. In case of varicocele, a cure of varicocele can be proposed. If the cause is hormonal, hormonal treatment can, in certain situations, revive spermatogenesis.
If oligospermia can not be treated, different MPA techniques will be proposed to the couple depending on the degree of oligospermia and TMS results:
- Intrauterine insemination (IUI) if the TMS shows at least 500,000 to 1 million motile spermatozoa. The simplest MPA technique, artificial insemination consists in depositing the most fertile spermatozoa in the uterus at the time of ovulation (induced in women after mild stimulation);
- In vitro fertilization (IVF) may be proposed in the event of failure of IUI, in case of oligospermia or more severe OATS. IVF consists of reproducing in the laboratory fertilization and the very first stages of embryonic development. For this purpose, oocytes are collected in the woman after ovarian stimulation, then brought into contact with spermatozoa previously prepared;
- In vitro fertilization with microinjection (ICSI) is often proposed in cases of severe oligospermia. This technique consists in selecting and preparing a spermatozoon to inject it directly into the mature oocyte for “forced” fertilization.