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Oligo astheno-teratospermia(OAT)

Oligo astheno-teratospermia(OAT)

Source: European Association of Urology (EAU) guidelines on Sexual and Reproductive Health, 2022.

Infertility is defined by the inability of a sexually active, non-contraceptive couple to achieve spontaneous pregnancy within 1 year. But the evaluation for infertility may at 6 months if the couple are above 30 years of age.


A complete medical history, physical examination and semen analysis are the essential

components of male infertility evaluation.


If semen analysis is normal according to WHO criteria, a single test is sufficient. If the results are abnormal on at least two tests, further andrological investigation is indicated.

According to WHO reference criteria 5th edition:

  • oligozoospermia: < 15 million spermatozoa/mL;
  • asthenozoospermia: < 32% progressive motile spermatozoa;
  • teratozoospermia: < 4% normal forms.

Often, all three anomalies occur simultaneously, which is defined as oligo-astheno-teratozoospermia (OAT) syndrome.


Sperm DNA Fragmentation Index (DFI):

Semen analysis is a descriptive evaluation and may be unable to discriminate between the sperm of fertile and infertile men. Therefore, it is now apparent that sperm DNA damage may occur in men with infertility. DNA fragmentation, or the accumulation of single- and double-strand DNA breaks, is a common property of sperm, and an increase in the level of sperm DNA fragmentation has been shown to reduce the chances of natural conception. Although no studies have unequivocally and directly tested the impact of sperm DNA damage on clinical management of infertile couples, sperm DNA damage is more common in infertile men and has been identified as a major contributor to male infertility, as well as poorer outcomes following ART including impaired embryo development, miscarriage, recurrent pregnancy loss, and birth defects. Sperm DNA damage can be increased by several factors including hormonal anomalies, varicocele, chronic infection and lifestyle factors (e.g., smoking).


The parallel assessment of the fertility status, including ovarian reserve, of the female partner during the diagnosis and management of the infertile male is very much essential as this might determine decision making in terms of timing and therapeutic strategies (e.g., assisted reproductive technology (ART) versus surgical intervention).