SDF Testing FAQs

Over the past 20 years, Examen has led pioneering research into Sperm DNA Fragmentation (SDF). Our Exact test, a direct measurement of global SDF, has consistently demonstrated excellent diagnostic accuracy for male infertility (AUC > 0.9 across multiple studies). This contrasts with indirect assays such as SCSA and SCD, which repeatedly show lower AUC values and, in some studies, perform no better than chance.

More recently, we developed Extend, powered by the neutral COMET assay and supported by ExamenLab’s proprietary, patent-pending technology. Extend is uniquely capable of measuring double-strand SDF alone, which is increasingly recognised as the clinically relevant form of DNA damage. Examen has led the global research effort into double-strand fragmentation, in collaboration with internationally recognised experts, including Prof. Scott Nelson, Prof. Stephen Drakeley (Hewitt Fertility), Prof. Sandro Esteves (Skive Hospital, Denmark) and Prof. Peter Humaidan (Horsens Hospital, Denmark).

Key prospective research findings

1. Recurrent Pregnancy Loss (RPL) – Hewitt Fertility
A recent prospective study of 100 men from RPL couples (no identified female factor) and 81 fertile controls demonstrated:
A strong association between double-strand SDF and male-factor RPL
AUC = 0.909 for double-strand SDF measured via Extend
66% of men in RPL couples had normal semen analysis, yet over half showed elevated double-strand SDF
This highlights the risk of missed diagnosis when male investigation stops at routine semen analysis.

2. IVF live-birth outcomes – Skive, Horsens, and Hewitt (n=302)
This multicentre prospective study found:
Higher double-strand SDF was strongly associated with lower IVF live-birth rates
Each 1% increase in double-strand SDF was associated with a 16% reduction in the odds of live birth (p=0.026)
The published data have been translated into a clinically useful predictive matrix combining female age and male double-strand SDF level to support personalised counselling around IVF prognosis.

In 2025, the Global Andrology Forum and the European Association of Urology updated their guidelines to recommend SDF testing in circumstances such as unexplained infertility, recurrent miscarriage and failed ART, based on the available evidence.

The WHO 6th edition discusses SDF under its extended investigations, and mentions it represents “one of the most discussed and promising biomarkers in basic and clinical andrology“.

1. Semen Analysis is not enough
Beyond confirming the presence of motile sperm, semen analysis has limited value in diagnosing male infertility. It has no prognostic value for ART and recurrent miscarriage.

2. Sperm DNA quality is central to male fertility
DNA integrity influences:
• Fertilisation
• Embryo development
• Implantation
• Ongoing pregnancy viability

3. High rates of missed male-factor infertility
SDF is a non-invasive way for men to gain a complete picture of sperm health.
Our research shows that >60% of men with normal semen analysis may still have elevated SDF. A normal analysis can therefore provide false reassurance, discouraging lifestyle improvement and delaying appropriate intervention.
Identifying elevated SDF instead:
• Creates a strong motivational trigger for lifestyle change
• Ensures ART planning accounts for compromised sperm quality

Diagnosis is important for patients
A recent Fertility Network survey highlights treatment uncertainty and lack of control as leading contributors to mental-health burden.

Clear diagnosis enables:
• Accurate risk counselling
• Appropriate expectations
• Targeted treatment planning

For example, men with SDF above the fertile threshold of 6% have 50% reduced odds of IVF live birth – a crucial factor to incorporate alongside female age during pre-ART counselling.

How does improved male investigation benefit couples?
Historically, infertility investigation and treatment have centred on women, contributing to significant emotional strain (40% of patients report suicidal feelings during treatment).

Thorough male evaluation:
• Reduces burden on women
• Encourages men to actively engage in their own health
• Promotes couple-level healthy behaviours
• Identifies treatable male-factor contributors before resorting to ART

Emerging evidence also links poor sperm quality with increased risks of childhood disease, underscoring the importance of optimising sperm DNA for both pregnancy outcomes and long-term offspring health.

Identifying elevated SDF opens multiple pathways to improve outcomes:

For clinicians
• Investigate for infections, varicocele, or unmanaged chronic disease
• Use SDF as leverage to motivate lifestyle optimisation
(Men receiving a “normal semen analysis” often perceive no need to change behaviour, even when suboptimal.)

For embryologists
• Consider sperm-selection devices (e.g., ZyMot)
– New data show significant reductions in double-strand SDF using these technologies.

For patients
• Target lifestyle factors known to impair sperm quality
• Use SDF as a measurable baseline to track improvement
• Optimise sperm health ahead of subsequent ART cycles (spermatogenesis refreshes every 2–3 months)
• Gain a greater sense of agency and shared responsibility within the couple

In the Fertility Network survey:
• Average spend on fertility treatment/investigation: £13,750
• 44.5% spent over £10,000
• Only 21% achieved a live birth

Examen’s SDF tests cost £360–£475 and are typically offered to patients for £500–£600 – around 4% of the average total spend.

Early investment in accurate diagnostics supports:
• More personalised treatment plans
• Better reproductive outcomes
• Improved clinic success rates (failed cycles negatively affect clinic metrics and patient acquisition)

While some patients may prioritise diagnostic ART cycles due to limited funds, offering SDF testing ensures informed choice – the cornerstone of patient-centred care.