Condition & Treatments
/ Sperm DNA fragmentation
Sperm DNA damage: the problem a normal semen test can't see
Sperm can look normal under the microscope and still carry broken DNA. High sperm DNA fragmentation is linked to lower natural pregnancy rates, poorer embryo development in IVF, and miscarriage. It is measured with a specific test, and it can often be reduced.
I N S H O R T
DNA fragmentation is measured on a semen sample, and reported as a percentage of sperm with damaged DNA.
Common causes are varicocele, infection, smoking, excess weight, heat, older age and long gaps between ejaculations.
Treating the cause can lower DNA damage within around three months.
Who should be tested
-
Couples with recurrent miscarriage.
-
Couples with failed IVF or ICSI, or poor embryo quality.
-
Unexplained infertility, where all other tests are normal.
-
Men with a varicocele and borderline semen results.
Tests
Sperm DNA fragmentation test (such as SCSA, TUNEL or SCD), in a lab that does the test regularly.
Scrotal ultrasound, to look for varicocele.
Semen culture, to look for infection.
Semen microbiome, using DNA sequencing to find bacterial imbalances that a standard culture can miss, which may contribute to DNA damage.
Hormone profile, where relevant.
Treatment options
Treating the cause:
varicocele repair, or antibiotics for infection.
Lifestyle changes:
stopping smoking, losing weight, avoiding heat and reducing alcohol.
Targeted antioxidants,
at the right dose and for the right length of time.
Shorter abstinence:
ejaculating more often, and producing the IVF sample after 1 to 2 days rather than longer.
Testicular sperm for ICSI:
for men with a good count but high DNA damage, sperm taken directly from the testis on the day of egg collection carries much less DNA damage than ejaculated sperm.
S P E C I A L I S T S E R V I C E
Fresh testicularsperm on the day of egg collection
For men with a good sperm count but persistently high DNA fragmentation, Prof Raheem can retrieve sperm directly from the testis on the same day as your partner's egg collection, for use in ICSI.
-
Less DNA damage. Testicular sperm usually carries two to three times less DNA damage than ejaculated sperm, because much of the damage happens as sperm travel through the tubes.
-
Better outcomes in studies. A meta-analysis found higher pregnancy and live birth rates and fewer miscarriages with testicular sperm in men with high DNA damage, although the evidence is still limited.
-
Co-ordinated with your IVF clinic, so the sperm is used fresh, without being frozen
Why this matters to your care
Prof Raheem supervised a 2019 research project at UCL's Institute for Women's Health, as part of the MSc in Prenatal Genetics and Fetal Medicine: a systematic review of how the male partner contributes to recurrent pregnancy loss in natural conceptions [5]. He uses DNA fragmentation results to guide treatment, not just to report a number.
What level is too high?
+
There is no single cut-off, because each test measures DNA damage differently. Published indicative levels are above about 17–20% for TUNEL, above about 25–30% for SCSA (often reported as the DFI), above about 15–25% for SCD, and above about 26% for the alkaline Comet test [1]. A DFI of 30% is the figure most often quoted [2], but results between about 20% and 40% are best seen as a grey zone [3]. These are guides, not absolute limits. A result above them doesn't mean pregnancy is impossible; it is linked with a longer time to conceive and a higher risk of miscarriage, and a result below them doesn't rule out a problem [4]. Prof Raheem interprets your result in context: the test and lab used, your other semen results, your partner's age, and the treatment you are planning.
My partner has had several miscarriages. Is it worth testing me?
+
Yes. Recurrent miscarriage guidelines now recommend checking the male partner.
Will antioxidants fix it on their own?
+
Sometimes, but finding and treating the cause usually matters more.
References
1. Sperm DNA fragmentation testing in the era of assisted reproduction: clinical utility, thresholds, and management strategies. Narrative review. Link
2. Sperm DNA fragmentation and its impact on pregnancy outcomes: a narrative review focusing on threshold definition and clinical strategies. Translational Andrology and Urology. Link
3. A single cut-off value of sperm DNA fragmentation testing does not fit all. Translational Andrology and Urology. Link
4. Utility of sperm DNA fragmentation testing in different clinical scenarios of male reproductive abnormalities and its influence in natural and assisted reproduction. Link
5. UCL EGA Institute for Women's Health. People: Reproductive Health, Dr Amr Abdel Raheem. Link