DNA Fragmentation Index (DFI) Medically Reviewed

Last Updated: April 7, 2020

Definition - What does DNA Fragmentation Index (DFI) mean?

DNA fragmentation index (DFI) is a measurement used to determine the amount of sperm that have abnormal genetic material.

Sperm contains half of the DNA required to fertilize an egg. If the DNA in sperm is damaged, it may be unable to fertilize the egg, or if fertilization occurs, the resulting embryo may fail to progress normally or properly implant into the uterine lining.

A DFI above 30% is related to infertility and above 20% is considered to be suboptimal. One study found that in couples with unexplained infertility 26% of men had a DFI of 20% or greater.

FertilitySmarts explains DNA Fragmentation Index (DFI)

A semen analysis is a common test to evaluate male infertility that assesses:

  • The number of sperm (concentration)
  • The shape of sperm (morphology)
  • Movement (motility)

A semen analysis does not assess DNA fragmentation. DNA fragmentation is a supplemental test to traditional sperm parameters assessed by a semen analysis.

How is DFI Evaluated?

The most common test for DNA fragmentation is the sperm chromatin structure assay (SCSA). The SCSA is a specialized test that stresses the sperm in an effort to break down the DNA. The sperm are then tested to determine how well thy can repair the broken DNA. The higher the DFI, the less likely the sperm will be able to fertilize an egg.

What causes high DFI?

There are multiple causes of a higher DFI, including:

  • Varicocele
  • Smoking
  • Age
  • Obesity
  • Testicular cancer
  • Infection

Some of these lifestyle factors can be controlled to reduce DFI and increase male fertility.

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