DNA Fragmentation Test
Advanced Insight Into Male Fertility Health
Even when standard semen analysis results appear normal, sperm can still carry hidden defects. One important factor is sperm DNA fragmentation (SDF), which refers to damage within the genetic material carried by sperm cells.
A range of health and lifestyle factors have been linked to increased sperm DNA damage. These include increasing paternal age, varicocele (enlarged veins in the testicles), infections in the reproductive tract, chronic illnesses, obesity, and diabetes. Environmental exposures such as toxins and pollution can also play a role, as can smoking, alcohol use, and long periods without ejaculation (Ribas-Maynou & Benet, 2019; Agarwal et al., 2014; Gosálvez et al., 2024; Pfeiffer et al., 2000).
Single-strand DNA breaks are most often caused by oxidative stress. Harmful molecules can come from within the body, for example due to inflammation or conditions such as varicocele (Ribas-Maynou & Benet, 2019), as well as from external sources like pollution, smoking, and poor nutrition, which can damage the DNA (Agarwal et al., 2014). These types of breaks can affect how well sperm move and are often linked to reduced chances of natural conception (Ribas-Maynou& Benet, 2019).
Double-strand DNA breaks are generally more serious because both sides of the DNA are damaged. These are often linked to problems in sperm development, how DNA is packaged, or failures in the normal process that removes damaged cells (Gosálvez et al., 2024; Pardiñas et al., 2022; Lange et al., 2011). They may also result from environmental exposures such as radiation or toxins (Pfeiffer et al., 2000). After fertilisation, the oocyte can repair some DNA damage usingnatural repair processes, but this ability is limited and influenced by maternal age. If the damage is too severe or not properly repaired, it may affect the stability of the embryo (Ribas-Maynou et al., 2022).
Fertility outcomes
This guide explains what sperm DNA fragmentation is, when testing is recommended, what results mean, and the typical DNA fragmentation test cost in the UK.
In terms of fertility outcomes, higher levels of sperm DNA fragmentation have been associated with delayed embryo development, reduced implantation (when the embryo attaches to the womb), and a higher risk of early miscarriage, particularly in couples where no female factor has been identified (Casanovas et al., 2019). Overall, increased SDF is linked to lower chances of natural pregnancy and reduced success in fertility treatments.
Therefore, sperm DNA fragmentation tests provide deeper insight into this hidden layer of male fertility health. At Fertility Solutions, we offer advanced sperm DNA Fragmentation testing in Beaconsfield, helping patients through their fertility journey.
A sperm DNA fragmentation (SDF) test is an advanced laboratory assessment that evaluates the genetic integrity of sperm DNA. While a standard semen analysis measures sperm quantity and physical characteristics, SDF testing looks deeper at the quality and stability of the genetic material carried within the sperm cell.
Sperm DNA damage can occur in two forms:
- Single-strand DNA breaks, where one strand of the DNA is damaged
- Double-strand DNA breaks, where both strands are damaged at the same time
Both types of damage can affect fertility, embryo development, and pregnancy outcomes. However, double-strand breaks are generally considered more severe because they are more difficult for the oocyte to repair after fertilisation.
A conventional semen analysis remains an important first step in male fertility assessment and evaluates both macroscopic and microscopic semen characteristics.
Macroscopic assessment includes:
- Semen volume
- PH
- Appearance and colour
- Viscosity
- Liquefaction
- Odour
Microscopic assessment includes:
- Sperm count
- Motility (movement)
- Morphology (shape)
- Vitality
- Debris or inflammatory cells
- Aggregation and agglutination
Although these parameters provide valuable information, men with normal semen analysis results can still have significant sperm DNA damage (Wen et al., 2025). This is why SDF testing can provide additional insight, particularly in cases of unexplained infertility, recurrent miscarriage, failed IVF cycles, or poor embryo development (Ribas-Maynou & Benet, 2019; Agarwal et al., 2020).
Types of sperm DNA Fragmentation tests
Several laboratory methods are used to assess sperm DNA fragmentation, and each detects different forms of DNA damage.
Sperm Chromatin Structure Assay (SCSA)
- The Sperm Chromatin Structure Assay (SCSA) is one of the most widely used and validated SDF tests. This technique uses a fluorescent dye to assess DNA stability within sperm cells. Healthy, intact DNA fluoresces green, while fragmented or damaged DNA fluoresces red.
- The results are reported as a DNA Fragmentation Index (DFI), which represents the percentage of sperm with damaged DNA. Higher DFI values are associated with lower fertility potential and poorer reproductive outcomes (Evenson, 2016).
- SCSA is valued for its standardisation, reproducibility, and ability to analyse thousands of sperm cells quickly using flow cytometry.
COMET Assay
- The Comet assay is one of the most detailed methods for assessing sperm DNA damage because it evaluates DNA fragmentation in individual sperm cells. During the test, damaged DNA migrates away from the sperm nucleus during electrophoresis, forming a shape that resembles a comet tail. The longer the tail, the greater the level of DNA damage.
- There are two versions of the Comet assay:
- Alkaline Comet assay – primarily detects single-strand DNA breaks
- Neutral Comet assay – specifically detects double-strand DNA breaks
- The neutral Comet assay is currently regarded as the only widely accepted method capable of reliably identifying double-strand DNA damage (Ribas-Maynou, García-Peiró, Abad, et al., 2012a).
High levels of sperm DNA fragmentation have been associated with:
- Reduced natural conception rates
- Lower IVF and ICSI success rates
- Poor embryo development (especially day 3–5 arrest)
- Increased risk of early miscarriage
- Unexplained infertility cases
Even when sperm parameters appear “normal”, DNA damage can still be present. This is particularly important in cases labelled as unexplained infertility, where standard testing does not reveal a clear cause. For many couples, this test provides the missing piece in a previously incomplete fertility picture.
If you are searching for a sperm DNA fragmentation London service, testing is typically recommended for:
- Couples with unexplained infertility - When routine fertility investigations show no clear cause.
- Recurrent miscarriage - Repeated early pregnancy loss may sometimes be linked to sperm DNA damage.
- IVF or ICSI failure - Especially where embryos fertilise but fail to progress to blastocyst stage.
- Male age over 40 - DNA fragmentation tends to increase with age due to oxidative stress.
- Lifestyle or medical risk factors including:
- Smoking
- Varicocele
- Obesity
- Heat exposure
- Chronic illness or infection
If any of these apply, your clinician may recommend advanced sperm testing as part of a wider fertility assessment.
Explore related investigations on our Male Fertility Health Hub
How is sperm DNA Fragmentation test performed?
At Fertility Solutions, the test is carried out using a semen sample collected under controlled laboratory conditions.
The sample is analysed using specialised techniques such as:
- SCSA (Sperm Chromatin Structure Assay)
- Neutral or Alkaline COMET assay
DNA Fragmentation test cost (UK & London)
One of the most common questions patients ask is about DNA fragmentation test cost.
In the UK, pricing typically ranges depending on:
- Test methodology
- Clinic location
- Whether consultation is included
- Laboratory processing standards
For a full breakdown of male fertility pricing, see our Fee Guide
Sperm DNA damage can occur during sperm production or transport and is often linked to oxidative stress.
Common contributing factors include:
- Lifestyle factors
- Smoking
- Excess alcohol consumption
- Poor diet
- Obesity
- Drug use
- Medical factors
- Varicocele (enlarged testicular veins)
- Infection or inflammation
- Hormonal imbalance
- Fever or recent illness
- Environmental factors
- Heat exposure (hot tubs, laptops on lap)
- Pollution
- Occupational toxins
- Age-related changes
Sperm DNA integrity naturally declines with age, particularly after 35–40 years.
Importantly, many of these factors are modifiable, meaning DNA fragmentation can sometimes improve with targeted intervention.
Depending on the underlying cause, DNA fragmentation levels can often be reduced (Agarwal et al., 2020).
Clinically supported strategies include:
- Lifestyle modification (smoking cessation, weight management)
- Treating varicocele where present
- Reducing heat exposure
- Managing infections or inflammation
Because sperm production takes approximately 74 days, improvements are typically reassessed after 3 months. Your clinician may recommend repeat testing following intervention to evaluate response.
In addition to addressing underlying causes, advanced sperm selection technologies may help reduce the impact of sperm DNA fragmentation during IVF or ICSI treatment. One increasingly used approach is microfluidic sperm selection, which mimics the natural sperm section process that occurs in the female reproductive tract (Pardiñas et al., 2022).
Unlike traditional sperm preparation methods that rely on centrifugation, which can increase oxidative stress and contribute to DNA damage, microfluidic systems gently isolate healthier sperm with better motility, morphology, and genetic integrity (Quinn et al., 2018; Pardiñas et al., 2022).
ZyMot is one of the most widely used microfluidic sperm selection systems. It is designed to select sperm with improved motility, morphology, and lower levels of DNA fragmentation, helping improve outcomes in assisted reproductive treatments (Pardiñas et al., 2022).
Studies have shown that sperm selected using ZyMot demonstrates significantly less DNA fragmentation compared with unprocessed sperm or sperm prepared using traditional methods such as density gradient centrifugation or swim-up (Quinn et al., 2018).
This is important because lower sperm DNA fragmentation has been associated with improved embryo development, higher implantation rates, and lower miscarriage risk (Casanovas et al., 2019; Ribas-Maynou et al., 2012).
While no method can guarantee successful pregnancy outcomes, technologies such as ZyMot may provide additional benefit for couples undergoing IVF or ICSI, particularly where sperm DNA fragmentation is a known concern (Pardiñas et al., 2022).
Clinical interpretation: why expert review matters
A DNA fragmentation result should never be interpreted in isolation.
At Fertility Solutions, results are reviewed by experienced fertility specialists who consider:
- Female partner’s age and ovarian reserve
- IVF history and embryo development patterns
- Previous semen analysis results
- Lifestyle and medical history
- Physical examination
This integrated approach ensures results are translated into meaningful clinical decisions rather than standalone percentages.
Internal links for further reading
To support a full fertility work-up, you may also find these resources helpful:
Professor Ramsay is a Consultant Urologist and one of the UK’s leading experts in male reproductive medicine. He has extensive experience in diagnosing and managing complex male infertility cases, including sperm DNA fragmentation, hormonal dysfunction, and unexplained infertility.
He has worked across leading UK fertility centres and contributes to advancing diagnostic pathways in male fertility care. His clinical focus includes:
- Advanced sperm function testing
- Evidence-based fertility diagnostics
- Individualised male fertility treatment pathways
- Improving IVF and natural conception outcomes through targeted intervention
Professor Ramsay is committed to ensuring patients receive accurate, clinically meaningful testing rather than unnecessary or non-evidence-based investigations.
You should consider booking a consultation if:
- You have been trying to conceive for over 6-12 months (or 6 months if partner is over 35).
- You have experienced recurrent miscarriage.
- IVF or ICSI cycles have failed.
- A standard semen analysis is “normal”, but conception is not occurring.
Early investigation can significantly improve treatment planning and outcomes.
References
Ribas-Maynou, J., & Benet, J. (2019). Single and Double Strand Sperm DNA Damage: Different Reproductive Effects on Male Fertility. Genes, 10(2), 105. https://doi.org/10.3390/genes10020105
Agarwal, A., Virk, G., Ong, C., & du Plessis, S. S. (2014). Effect of Oxidative Stress on Male Reproduction. The World Journal of Men’s Health, 32(1), 1–17 https://doi.org/10.5534/wjmh.2014.32.1.1
Gosálvez, J., Johnston, S. D., Prado, A., López-Fernández, C., Contreras, P., Bartolomé-Nebreda, J., González-Martínez, M., Fernández, J. L., De La Vega, C. G., & Góngora, A. (2024). Strong Correlation Between Double-Strand DNA Breaks and Total Sperm DNA Fragmentation in the Human Ejaculate. Archives of Medical Research, 55(8), 103122. https://doi.org/10.1016/j.arcmed.2024.103122
Pfeiffer, P., Goedecke, W., & Obe, G. (2000). Mechanisms of DNA double-strand break repair and their potential to induce chromosomal aberrations. Mutagenesis, 15(4), 289–302. https://doi.org/10.1093/mutage/15.4.289
Lange, J., Pan, J., Cole, F., Thelen, M. P., Jasin, M., & Keeney, S. (2011). ATM controls meiotic double-strand break formation. Nature, 479(7372), 237–240. https://doi.org/10.1038/nature10508
Ribas-Maynou, J., Novo, S., Torres, M., Salas-Huetos, A., Rovira, S., Antich, M., & Yeste, M. (2022). Sperm DNA integrity does play a crucial role for embryo development after ICSI, notably when good-quality oocytes from young donors are used. Biological Research, 55(1), 41.https://doi.org/10.1186/s40659-022-00409-y
Casanovas, A., Ribas-Maynou, J., Lara-Cerrillo, S., Jimenez-Macedo, A. R., Hortal, O., Benet, J., Carrera, J., & García-Peiró, A. (2019a). Double-stranded sperm DNA damage is a cause of delay in embryo development and can impair implantation rates. Fertility and Sterility, 111(4), 699-707.e1. https://doi.org/10.1016/j.fertnstert.2018.11.035