Sperm DNA fragmentation (SDF)
Assays, thresholds, and impact on IVF/ICSI/IUI and miscarriage
Last updated: October 2026 — Sources: Cochrane / EAU / ESHRE / WHO / CDC
Key takeaways
SDF is not a general fertility test — it's an add-on for RPL, implantation failure, or unexplained with borderline semen. Umbrella 2026 & 2025 meta show association but high heterogeneity and varying thresholds.
Assays (SCSA/TUNEL/SCD/Comet) give different DFI — no single cutoff: 15%/27%/30% all used.
Umbrella 2026: high SDF lowers IVF CP RR 0.66 & IUI 0.47, raises ICSI miscarriage RR 2.29 — low certainty, retrospective.
DFI ≥30% lowers euploid embryos OR 0.74 in 2025 meta — no effect at 15%.
EAU 2025: assess SDF in RPL/implantation failure — Strong; not routine for all.
When to evaluate?
- RPL ≥2 with borderline semen.
- Repeated unexplained IUI/IVF failure.
- Unexplained >12 mo, near-normal semen — to discuss lifestyle/antioxidants cautiously.
What not to do?
- Don't use DFI alone to choose ICSI vs IVF — multifactor decision.
- Don't promise ‘lower SDF = guaranteed pregnancy’ — trials didn't prove causality.
- Don't mix assays when comparing — each lab & cutoff.
Healthcare-professional notice
This hub is independent of NPF products and does not promote them. It is informational only and does not replace individual clinical judgment. Surrogate outcomes (SDF, motility, HOMA, IIEF) are never converted into pregnancy/cure promises, and GRADE certainty is quoted as published.
Binding rule: surrogate outcomes are never converted into patient outcomes. Every certainty grade and limitation is quoted as published.
Deep dive
Assays & cutoffs
SCSA most standardized, TUNEL direct breaks, SCD cheap but operator-dependent. WHO 6th lists as Extended without cutoff.
2025 meta: 30% cutoff showed effect on euploidy — 15% didn't.
Testicular sperm for high SDF?
Esteves 2017: testicular ICSI may raise live birth OR 2.58 & lower miscarriage, but small observational — not routine.
EAU not routine; discuss only after repeated failure with counselling.
Evidence in this domain
Each study broken into five questions: why it was run, who was studied, how it was done, the finding, and why it came out that way — then the clinical takeaway and limits, as published.
FAQ
Do antioxidants lower SDF?
MOXI & SUMMER showed no consistent SDF fall; some CoQ10 studies showed drop but no proven pregnancy.
Notice: this reference is informational only and not a substitute for medical advice. Consult your doctor before making any treatment decision.