MLT GlobeSperm DNA fragmentation index (DFI)
Semen & Infertility · also called SDF test, SCSA, TUNEL
What it measures
Measures the proportion of sperm with broken DNA strands. It is used in unexplained infertility, recurrent miscarriage and failed IVF/ICSI.
Specimen and preparation
- Specimen: Fresh semen
- Tube: Semen top
- Preparation: 2–7 days abstinence; deliver promptly.
Reference range
| Group | Range |
|---|---|
| Normal | < 15 (method dependent) % DFI |
| Intermediate | 15–30 % DFI |
| High | > 30 % DFI |
Reference ranges differ between laboratories, methods and populations. Always use the range printed on your own lab report.
Causes of high values
- Varicocele
- Smoking, heat exposure, oxidative stress
- Advanced paternal age
- Infection or leukocytospermia
Method
Sperm chromatin structure assay (flow cytometry), TUNEL, SCD (Halo) or Comet assay
Good to know
Cut-offs are assay-specific; high DFI may favour ICSI or treatment of reversible causes.
Related tests
📱 Practise with a timer, track your score and earn certificates in the free MLT Globe app – Google Play or practise online.