Male Infertility: Current Challenges and the Role of Sperm DNA Fragmentation

Normal spermogram results do not always rule out male infertility. In some cases, difficulties in achieving a pregnancy may be associated with impaired sperm DNA integrity, information that is not assessed through conventional semen analysis alone. Sperm DNA fragmentation testing may provide additional insights in cases of unexplained infertility, varicocele, recurrent pregnancy loss or repeated IVF/ICSI failure. Learn what sperm DNA fragmentation is, when testing may be recommended, and how it contributes to the modern evaluation of male infertility.

Male infertility is one of the major reproductive health challenges worldwide, contributing to approximately half of all cases of infertility in couples.

In recent years, research in andrology has shown that conventional semen analysis is not always sufficient to explain difficulties in achieving a pregnancy. As a result, increasing attention has been given to assessing sperm DNA integrity and to developing more advanced methods for the diagnosis and treatment of male infertility.

What Is Male Infertility?

Male infertility is defined as a man's inability to contribute to achieving a pregnancy after at least 12 months of regular, unprotected sexual intercourse.

Its causes are diverse and may include:

• hormonal disorders 
• varicocele
• infections of the male reproductive tract
• genetic abnormalities
• obstruction of the seminal tract
• lifestyle-related factors
• exposure to toxins or radiation
• impaired sperm DNA integrity

In many cases, however, no clear cause can be identified. This is referred to as idiopathic male infertility.

Conventional Semen Analysis and Its Limitations

The standard assessment of male fertility is based primarily on semen analysis, which evaluates:

• sperm concentration 
• sperm motility
• sperm morphology 
• ejaculate volume

Although semen analysis remains an essential investigation, numerous studies have shown that some men with apparently normal semen parameters may still experience reduced fertility.

In these cases, sperm DNA damage may provide additional information that can help explain reproductive failure, recurrent pregnancy loss or poor outcomes following in vitro fertilization.

What Is Sperm DNA Fragmentation?

Sperm DNA fragmentation (SDF) refers to damage to the genetic material carried by sperm cells.

The integrity of sperm DNA is important for fertilization, embryo development and the establishment of a healthy pregnancy.

Recent research has associated elevated sperm DNA fragmentation with:

• reduced natural fertility
• lower success rates in assisted reproductive treatments
• an increased risk of miscarriage
• impaired embryo development

What Causes Sperm DNA Damage?

Several mechanisms and factors may contribute to sperm DNA damage.

Oxidative stress

Oxidative stress is considered one of the main mechanisms involved. Reactive oxygen species can damage both the sperm membrane and sperm DNA.

Defects in spermatogenesis

DNA damage may occur during the process through which sperm cells are produced and mature.

Infection and inflammation

Inflammatory processes and infections of the reproductive tract may increase the production of reactive oxygen species and contribute to oxidative stress.

Varicocele

Varicocele may increase testicular temperature and oxidative stress and is associated with impaired sperm quality in some men.

Advanced paternal age

Increasing age may be associated with greater sperm DNA damage.

Environmental and lifestyle factors

Smoking, obesity, alcohol and drug use, pollution and exposure to pesticides are among the factors that may negatively affect sperm quality and DNA integrity.

How Is Sperm DNA Fragmentation Tested?

Sperm DNA fragmentation tests provide information beyond that obtained from conventional semen analysis and may be useful in selected clinical situations.

Several methods are currently used to assess sperm DNA integrity, including:

• TUNEL assay 
• SCSA (Sperm Chromatin Structure Assay) 
• Comet assay 
• SCD (Sperm Chromatin Dispersion) test 

The results should always be interpreted in the context of the patient's complete clinical and reproductive history.

When Is Sperm DNA Fragmentation Testing Recommended?

According to current clinical recommendations, SDF testing may provide useful additional information in several clinical scenarios.

Varicocele

Varicocele is one of the most common treatable causes of male infertility. Studies have shown that men with varicocele frequently have elevated levels of sperm DNA fragmentation.

In appropriately selected patients, surgical treatment may reduce DNA damage and improve fertility parameters.

Unexplained infertility

When conventional fertility investigations do not identify a clear cause, sperm DNA fragmentation testing may reveal an additional factor that could contribute to infertility.

Recurrent pregnancy loss

Elevated sperm DNA fragmentation has been associated with recurrent pregnancy loss. The genetic integrity of the sperm cell is an important factor in normal embryo development.

Repeated IVF/ICSI failure

Couples who have experienced repeated unsuccessful assisted reproduction cycles may benefit, in selected cases, from assessment of sperm DNA fragmentation.

Exposure to risk factors

Testing may also be considered in men exposed to factors associated with impaired sperm quality, including:

• smoking 
• obesity 
• pollution 
• pesticides 
• radiation 
• high temperatures 
• oncological treatments 

New Directions in the Diagnosis of Male Infertility

Artificial Intelligence and Semen Analysis

Artificial intelligence is increasingly being explored for automated sperm assessment, with the potential to reduce observer variability and support sperm selection for assisted reproductive procedures.

Advanced Genetic Testing

Modern genetic technologies can identify certain mutations and chromosomal abnormalities that may not be detected through conventional fertility investigations.

Genetic evaluation can be particularly relevant in severe male infertility and azoospermia.

Molecular Biomarkers

Researchers are investigating new biomarkers associated with male fertility, including microRNAs, proteins and epigenetic markers that may eventually help predict reproductive outcomes.

Selecting Sperm With Better DNA Integrity

Advanced sperm-selection methods have been developed for IVF/ICSI procedures with the aim of selecting spermatozoa with more favorable characteristics and potentially better genetic integrity. These include technologies such as ZyMōt and MACS.

Treatment of Male Infertility

The management of male infertility should be individualized and, whenever possible, directed towards its underlying cause.

Lifestyle Changes

Lifestyle interventions may contribute to improving sperm quality and reducing factors associated with sperm DNA damage. These may include:

• smoking cessation 
• reducing alcohol consumption 
• maintaining a healthy body weight 
• regular moderate physical activity 
• stress management 
• adequate sleep 
• avoiding excessive testicular heat exposure

Antioxidants

Because oxidative stress is an important mechanism involved in sperm DNA damage, antioxidants are frequently considered in male infertility management.

Evidence regarding their effectiveness remains variable, although some studies have reported improvements in sperm parameters and reductions in DNA fragmentation.

Varicocele Treatment

In appropriately selected patients, surgical correction of varicocele may improve semen parameters and sperm DNA integrity.

Assisted Reproductive Technologies

When conservative treatment is insufficient, assisted reproductive techniques may be considered, including:

• intrauterine insemination (IUI)
• in vitro fertilization (IVF) 
• intracytoplasmic sperm injection (ICSI)

In selected severe cases, the use of sperm retrieved directly from the testis rather than ejaculated sperm may be considered as part of the reproductive strategy.

Future Perspectives

The future of male infertility diagnosis and treatment is likely to be increasingly shaped by personalized medicine.

The integration of artificial intelligence, genomics and molecular biomarkers may help clinicians identify underlying causes more precisely and select more individualized treatment strategies.

At the same time, ongoing research into sperm DNA protection and the reduction of oxidative stress may contribute to improving both natural and assisted reproductive outcomes.

Conclusions

Male infertility is a complex condition influenced by genetic, biological, environmental and lifestyle factors.

Conventional semen analysis remains a fundamental component of male fertility assessment. However, in selected clinical situations, sperm DNA fragmentation testing can provide additional information that conventional semen parameters alone may not reveal.

Emerging diagnostic technologies are opening new possibilities for identifying previously unexplained causes of male infertility and for developing increasingly personalized treatment strategies.

At the same time, prevention, lifestyle optimization and early evaluation remain important components of male reproductive health.

References

• Murat Gul, Giorgio Ivan Russo. Male Infertility: New Developments, Current Challenges and Future Directions. 
• Andrabi SW, et al. Sperm DNA Fragmentation: Causes, Evaluation and Management in Male Infertility. Assisted Reprod. 2024. 
• Chak-Lam Cho, Ashok Agarwal. Clinical Utility of Sperm DNA Fragmentation Testing: Practice Recommendations Based on Clinical Scenarios. 
• World Health Organization. WHO Laboratory Manual for the Examination and Processing of Human Semen, 6th Edition. 
• American Urological Association/American Society for Reproductive Medicine. AUA/ASRM Guideline.