English EN

Sperm DNA Fragmentation: Its Impact on Fertility and Assisted Reproductive Technologies


Sperm DNA fragmentation is one of the key factors affecting male fertility. This process involves the damage of DNA strands in the sperm head, which disrupts the transmission of genetic material and can lead to infertility.

Research shows that the normal structure of sperm DNA is critical for successful conception and normal embryo development. Standard sperm analysis, conducted in accordance with World Health Organization (WHO) guidelines, evaluates parameters such as sperm concentration, motility, and morphology, but it does not detect DNA damage. As a result, even men with normal sperm parameters may encounter fertility issues, necessitating additional diagnostics, particularly sperm DNA fragmentation testing.

Frequency and Causes of DNA Fragmentation

Sperm DNA fragmentation can vary among men depending on a range of factors. Studies show that in healthy men, the proportion of sperm with fragmented DNA does not exceed 15%. If DNA fragmentation levels reach 30% or more, this significantly reduces the likelihood of successful conception and increases the risk of pregnancy complications. Statistics indicate that in 25% of men with normal sperm parameters, DNA fragmentation testing reveals structural abnormalities.

The primary causes of DNA fragmentation include:

  • Oxidative stress – one of the main factors contributing to DNA damage in sperm. Excessive reactive oxygen species (ROS) in the body can damage cells, including sperm DNA. Studies have shown that oxidative stress is associated with reduced sperm motility and an increased number of damaged cells.

  • Age – As men age, sperm DNA fragmentation levels increase. After the age of 40, the likelihood of DNA fragmentation rises by 10-15%, linked to the accumulation of cell damage.

  • Infections and inflammatory diseases – Chronic infections of the urogenital system, such as prostatitis or epididymitis, can lead to increased DNA damage in sperm.

  • Varicocele – A condition in which veins in the spermatic cord enlarge, disrupting the testicular thermoregulation and impairing sperm quality. Up to 40% of men with varicocele exhibit elevated DNA fragmentation levels.

  • Poor environmental and toxic factors – Exposure to industrial toxins, radiation, smoking, and excessive alcohol consumption also increase DNA damage in sperm.

  • Medications – Chemotherapy and radiation therapy can significantly increase DNA fragmentation levels, negatively affecting male fertility.

The Impact of DNA Fragmentation on ART Outcomes

Sperm DNA fragmentation significantly affects the outcomes of assisted reproductive technology (ART) programs, including IVF and intracytoplasmic sperm injection (ICSI).

Multiple studies confirm that men with high levels of sperm DNA fragmentation (above 30%) have lower chances of success with IVF. One study involving over 500 men revealed that in patients with DNA fragmentation levels above 30%, the likelihood of achieving pregnancy through IVF decreased by 25%. Additionally, such men are more likely to experience repeated ART failures and early embryo loss.

A sperm DNA fragmentation test can help predict ART outcomes and guide clinicians in selecting the appropriate treatment. For instance, if DNA fragmentation levels exceed 30-50%, IVF with ICSI is recommended, where an embryologist manually selects sperm for fertilization. This method allows the selection of sperm with minimal DNA damage, improving the chances of a successful outcome.

Methods for Diagnosing DNA Fragmentation

There are several methods for assessing sperm DNA fragmentation, the most commonly used ones include:

  1. TUNEL (Terminal deoxynucleotidyl transferase dUTP nick end labeling) – a method of directly labeling DNA breaks, allowing visualization of damaged DNA segments using fluorochromes.

  2. SCSA (Sperm Chromatin Structure Assay) – a method that evaluates chromatin stability and detects DNA damage using fluorescent dyes.

  3. COMET (Comet Assay) – a single-cell electrophoresis method that assesses the degree of DNA breaks in sperm.

  4. Halosperm – a method that stains sperm samples and assesses the halo around the sperm, indicating DNA damage.

Each method has its advantages and unique features, but the most widely used in clinical practice is the TUNEL test, which provides high accuracy and valuable information.

Test Results and Interpretation

Sperm DNA fragmentation test results are typically expressed as a percentage. Here are the key levels used in clinical practice:

  • Less than 15% – normal level, conception is possible naturally, and the risk of miscarriage is minimal.

  • 15-30% – spontaneous pregnancy is possible, but with an increased risk of complications and miscarriage.

  • 30-50% – natural conception is unlikely; IVF with ICSI is recommended.

  • More than 50-60% – the chances of successful conception are significantly reduced, and donor sperm may be required.

Test Preparation and Recommendations

Before undergoing a sperm DNA fragmentation test, the following steps should be followed:

  • Abstain from sexual activity for 5-7 days before the test.

  • Avoid overheating the body (e.g., saunas, hot baths).

  • Eliminate alcohol and minimize smoking.

  • Avoid heavy physical and emotional stress.

  • If the patient has had an infection or taken antibiotics, the test should be postponed for two weeks after recovery.

Treatment of DNA Fragmentation

The primary focus of treating elevated sperm DNA fragmentation is addressing the underlying causes of damage. In many cases, lifestyle changes, quitting harmful habits, and taking antioxidants can significantly improve sperm quality. Research shows that taking antioxidants such as vitamin C and E can reduce DNA fragmentation levels by 10-20%.

If the cause of DNA fragmentation cannot be eliminated, assisted reproductive technologies (ART) are employed. ICSI allows the selection of sperm with the least damage, improving the chances of successful fertilization. In more severe cases, donor sperm may be recommended.

Of particular note is surrogacy in Cyprus, where advanced assisted reproductive technologies, including IVF and ICSI, are applied. Surrogacy programs offer patients with high sperm DNA fragmentation levels, where natural conception is impossible, the opportunity to become parents through the use of donor material or their own gametes with proper selection.