THE SIMPLE VERSION
Your DNA fragmentation index (DFI) is the percentage of sperm with damaged DNA. Lower is better, but there’s no single cutoff that applies to every test: each lab method and each lab sets its own ranges. Read your number against the range on your own report, and go through it with a clinician.
What your DNA fragmentation report shows
Most reports give a DNA fragmentation index (DFI): the estimated percentage of sperm with damaged DNA. For example, a DFI of 20% means about one in five sperm had DNA damage.
Some methods add other numbers. SCSA reports, for example, often include HDS (high DNA stainability). It’s a marker of sperm whose DNA isn’t packed as tightly as it should be.2
How DFI results are usually grouped
Labs and studies use different cutoffs, and each lab sets its own reference range.1 For SCSA, the most widely studied method, results are often grouped like this:
These ranges only apply to SCSA. Always read your number against the range printed on your own report.
Why the lab method matters for your result
Labs use four main methods: SCSA, TUNEL, SCD and COMET. They measure DNA damage in different ways and report on different scales. So 20% on one test doesn’t mean the same thing as 20% on another.12
Your report should name the method. If it doesn’t, ask the lab. If you retest, use the same method.
What a higher DFI can mean
Studies have linked higher DNA fragmentation with taking longer to get pregnant and a higher chance of miscarriage. Some also link it with lower success in fertility treatment, though findings vary.1
A higher result isn’t a diagnosis on its own. It doesn’t mean pregnancy is out of reach.
What to do next with your DFI result
- Share the full report with a urologist or fertility specialist.
- Ask about possible causes, such as a varicocele, smoking, heat, infection or long gaps between ejaculations. Our guide to lowering DNA fragmentation covers the options.
- If you retest, wait about three months and use the same method and lab.
- If you’re having IVF, ask your clinic whether the result changes how it selects sperm.1
A DFI result is most useful alongside a full fertility evaluation of both partners. On its own, it isn’t a reason to start or change treatment.
If you haven’t had a DNA fragmentation test yet
Testing isn’t necessary for everyone. Guidelines suggest considering it in specific situations, such as repeated miscarriage.3
If you and your clinician decide to test, our comparison shows the price, method and results time for each at-home option.
Common questions about DFI results
What is a normal DFI?
There’s no universal normal. Each method and lab sets its own ranges, so use the range printed on your report.1
Can I compare my result with a friend’s, or with an older test?
Only if both used the same method, ideally at the same lab. A 20% on one method doesn’t mean the same as 20% on another.12
Does a high DFI mean I can’t have children?
No. A higher result has been linked to a lower chance of pregnancy in some studies, but it isn’t a diagnosis on its own, and many people with high results still conceive.1
When should I retest?
If you retest, wait about three months, the time new sperm take to develop, and use the same method and lab.
SCIENTIFIC SOURCES
- Agarwal A, Majzoub A, Baskaran S, et al. Sperm DNA fragmentation: a new guideline for clinicians. World J Mens Health. 2020;38(4):412–471. doi:10.5534/wjmh.200128
- Evenson DP. The Sperm Chromatin Structure Assay (SCSA®) and other sperm DNA fragmentation tests for evaluation of sperm nuclear DNA integrity as related to fertility. Anim Reprod Sci. 2016;169:56–75. doi:10.1016/j.anireprosci.2016.01.017
- Schlegel PN, Sigman M, Collura B, et al. Diagnosis and treatment of infertility in men: AUA/ASRM guideline part I. J Urol. 2021;205(1):36–43. doi:10.1097/JU.0000000000001521