What is the test?
A sperm DNA fragmentation (SDF) test measures the proportion of sperm in a sample with damaged or broken DNA.
What does it assess?
Sperm DNA integrity, which standard semen analysis does not measure.
Who might need it?
It may be considered in selected cases, such as recurrent miscarriage, repeated unexplained IVF failure, or when a specialist feels it could change management.
When is it performed?
Usually after standard semen analysis and other investigations, on specialist advice.
How is the test carried out?
A semen sample is produced in the same way as for a standard semen analysis and processed using one of several laboratory methods.
How should I prepare?
Follow the same abstinence guidance as for semen analysis; your clinic will advise.
What can the results mean?
Results are reported as a percentage (DNA fragmentation index). Thresholds differ between test methods and labs.
What are its limitations?
Different methods give different results, and evidence that acting on results improves live birth rates is limited. Results should be interpreted by a specialist.
Is it routinely recommended?
Not recommended as a universal first-line test. The HFEA lists sperm DNA testing among treatment add-ons with limited evidence.
What happens next?
A specialist may discuss lifestyle factors, treating underlying causes such as varicocele, or treatment options. Ask what difference the result would make before paying.
Before paying for additional tests, read the HFEA Treatment Add-ons guidance.
Frequently asked questions
Can DNA fragmentation be reduced?
Stopping smoking, reducing heat exposure and treating infections or varicoceles may help in some cases, though evidence varies.