SDI ( Sperm DNA Integrity)
Sperm DNA quality is essential to successful fertilisation and embryo development.
The quality of the sperm’s chromatin is a crucial factor in male infertility due to the impact of the sperm’s genetic material on early embryo development. Analysis of the chromatin structure has predictive value for the fertilisation outcome and the success of assisted reproduction techniques. The SDI test gives insight into the distribution of sperm with no DNA fragmentation, sperm with fragmented DNA, and sperm with immature chromatin. The extent of damage to the sperm’s genetic material is numerically expressed, with results represented as % in two indices, DFI (DNA fragmentation index) and HDS (high DNA stainability index, showing immature chromatin).
Research shows that sperm can be classified into three groups of fertilising capacity according to their fragmentation index
HALO test – a method for assessing DNA damage
In its essence, the Halo test is similar to the SDI test. It reports the structural integrity of sperm chromatin in %. It is indicated in men with lower sperm concentration in the ejaculate (less than 3 mln spermatozoa in the total volume).
Sperm viability test
This test uses sperm staining to determine the percentage of viable spermatozoa. It is necessary when no motile sperm are present or when the ratio of immotile sperm is > 72%.
Semen antioxidant test
Oxidative stress is an invariable part of metabolic processes in every living organism that utilises oxygen. It is the condition where the homeostasis balance is disturbed, resulting in a cascade-like elevation of free radical levels in the body, which can be especially detrimental to spermatogenesis. A specific feature of spermatozoa explains their vulnerability – while most cells in our bodies have membranes containing saturated fatty acids, the sperm membrane has a very high content of unsaturated fatty acids. They are highly polar and, therefore, an easy target for free radicals. When free radicals attack the sperm membrane, its integrity is affected, leading to the loss of its primary function, selective permeability. As a result, various toxins can freely enter the sperm cell.
To fight free radicals and oxidative stress as a whole, the human body has developed antioxidant defence mechanisms in the form of several specialised enzymes – big protein complexes that can efficiently scavenge and turn free radicals into harmless substances. However, these antioxidant enzymes need some essential micronutrients, which are lacking in our geographical region, so oxidative stress here is very prominent.
That is why in patients with spermatogenesis problems of unknown origin, it is recommended to check for oxidative stress as a possible cause.
Even with normal semen parameters, in cases of unexplained infertility, the underlying cause can turn out to be oxidative stress.
Free radicals attack the genetic material in spermatozoa. Since the primary function of sperm is to pass on its genetic material to the egg, forming the future embryo, any damage to the sperm genetic material can pose a risk for the embryo too – it can have abnormal development or not be viable at all, resulting in difficulty to conceive.
How is sperm oxidative stress diagnosed?
Oxidative stress in sperm is diagnosed by the so-called antioxidant test – a specific assay for measuring the activity levels of two key antioxidant enzymes in semen, seminal plasma and spermatozoa. Those are glutathione peroxidase (GPx) and superoxide dismutase (SOD). In contrast to other labs that use blood serum for this test, the test has been adapted and validated at Nadezhda hospital to measure enzymatic activity in semen itself.
Which factors contribute to oxidative stress?
Oxidative stress prevention and treatment
Along with increased physical activity and lifestyle changes to correct diet and unhealthy habits, an essential part of oxidative stress prevention is supplements of deficient micronutrients needed for the enzymes to work. The recovery process is lengthy because, first, the normal rates and pathways of the metabolic processes have to be restored. Only then the cycle of spermatogenesis can return to normal, producing healthy, viable sperm with good fertilisation potential.
Antisperm antibodies test
Approximately 5–7 % of infertile men have antibodies against their own sperm.
These antibodies can have a detrimental effect on the fertilising capacity of spermatozoa because binding to them leads to blocking their normal movement through the female reproductive tract.
Antisperm antibodies could also prevent sperm-oocyte interactions at the time of fertilisation. In some cases, these antibodies could adversely impact spermatogenesis.
Antisperm antibodies could appear after surgery to the testis, trauma or vasectomy when sperm are reabsorbed in the epididymis. There are cases when no cause for the presence of antisperm antibodies can be identified.
When antisperm antibodies are present, the so-called sperm agglutination, or clumping, is often observed. Sperm cells carry a negative surface charge that makes them constantly repel each other. Antibodies lead to change or loss of this negative charge, which results in sperm clumping, or agglutination.
White blood cell count in semen
The presence of leukocytes, or white blood cells, in semen (over 1 mln) is an alarming finding signalling inflammation of the genital tract (inflammation of the epididymis, testis, or prostate, or varicocele), bacterial infection or other condition. Leukocytospermia, the unusually high number of white blood cells in semen, is linked to increased numbers of immature spermatozoa, increased DNA damage, and ultimately, fertilisation failure.
When semen analysis shows abnormal results, it is necessary to assign additional testing, like hormone blood tests, a testicular biopsy, etc.