The acronym OATS (or oligo-astheno-teratozoospermia) refers to a common sperm abnormality that may require medically assisted reproduction. What is the OATS due to? What type of treatment may be recommended by your doctor? What are the chances of seeing your child project succeed? Decryption.

When a couple consults because they are having difficulty conceiving, the first test indicated to identify possible male infertility is a spermogram. Its objective: to determine if there is a spermatic disorder linked to:

• an anomaly of number: when the number of spermatozoa in the semen is considered insufficient, one speaks of oligozoospermia (or oligospermia). When they are absent, a diagnosis of azoospermia is made. In both cases, a spontaneous pregnancy is very difficult, if not impossible;
• a mobility abnormality: the spermogram then reveals a rate of immobile spermatozoa in the sperm that is too high compared to the motile gametes. It is asthenospermia, which can explain why fertilization and therefore pregnancy do not take place;
• an abnormal shape: in about one in 10 infertile men, the spermogram reveals an abnormal shape of the sperm which may explain why they lose their ability to fertilize the oocyte. This is called teratospermia.

L’OATS or oligo-astheno-teratozoospermia is a spermatic abnormality grouping together these three main categories. In case of OATS (or OAT), the spermogram reveals:

• too low a concentration of sperm in semen;
• too low a motile sperm count;
• too high a count of malformed sperm.

The management of OATS is linked to its severity. In fact, oligo-astheno-teratozoospermia can be classified on a scale ranging from moderate (when the spermogram is almost normal) to very severe (when less than a million spermatozoa per milliliter are identified, very little mobile and presenting a high proportion of anomalies).

OATS is the most common cause of male infertility and affects more than one in five infertile men in France (21%).

Infections, genetic diseases, malformations, hormonal disorders, etc. Like other sperm abnormalities, OATS can have many causes that your doctor will try to identify in order to recommend appropriate management and / or treatment.

When they are pathological, these causes are generally classified into three families making it possible to specify their location in relation to the male genital system:

• pretesticular causes: OATS can then be explained, among other things, by gonadotropic hypogonadism (a disorder of the pituitary gland which affects in particular the function of the testis), or dysthyroidism. OATS may also be due to a chromosomal or genetic disorder (such as balanced chromosomal translocation, Klinefelter syndrome, Kallman syndrome, Y chromosome microdeletions), although it is often the diagnosis of azoospermia which, in these cases, prevails;
• testicular causes, again with gonadotropic hypogonadism;
• post-testicular causes and particularly infections of the reproductive system (urethritis, prostatitis, epididymitis) when they have left sequelae.

Other less obvious causes can also be investigated on a case-by-case basis, such as:

• heavy medical treatment (irradiation, anticancer drugs);
• a varicocele;
• cryptorchidism: it is then the excessively high temperature to which the testes are exposed that would have a deleterious impact on spermatogenesis;
• testicular cancer;
• an abnormality of the excretory system of the testes (vas deferens).

Note: it often happens that the causes of OATS are not found, which fortunately does not prevent management of related male infertility.

In case of suspicion of oligo-astheno-teratozoospermia, your doctor will recommend above all to redo a spermogram within 3 months to confirm the diagnosis. He may also conduct or prescribe various examinations to clarify the causes of your OATS (clinical examination, scrotal ultrasound, hormonal assessment), or even recommend additional genetic investigations (karyotype, evaluation of microdeletions of the Y chromosome) under certain conditions.

Once the cause of OATS has been identified, your doctor will seek to treat it if possible.

Treatments

The treatments then vary depending on the origin of the anomaly:

• hormone replacement therapy in cases of gonadotropic hypogonadism (again, in those affected);
• treatment of hyper or hypothyroidism or infections;
• surgical management of varicocele;
• etc.

If your OATS is considered idiopathic (with no known cause), your doctor may prescribe treatment with FSH, the follicle stimulating hormone, to try to improve the quantity and quality of semen.

Finally, your doctor will surely recommend that you stop smoking, alcohol (when consumed in excess) or weight loss (if you are overweight or obese). Indeed, all these measures related to healthy living can promote better sperm quality.

While it is true that the (very) poor quality of semen in the event of OATS can constitute a brake on spontaneous pregnancy, the latter is however not impossible, especially if you suffer from moderate OATS. However, your doctor may recommend medically assisted procreation, taking into account your partner’s age, the time since stopping birth control and the severity of the sperm disorder. Depending on your particularities, the team that follows you can guide you towards artificial insemination, IVF or IVF with ICSI in the event of severe OATS. The chances of pregnancy are then, on average, one in four during each cycle of IVF and ICSI.