DNA Fragmentation Index (DFI)
Definition - What does DNA Fragmentation Index (DFI) mean?
DNA fragmentation index (DFI) is a measurement of sperm affected by DNA damage. Sperm contains half of the DNA required to fertilize an egg. If the DNA in a sperm is damaged, it may be either unable to fertilize the egg, or the resulting embryo will fail to progress and properly implant into the uterine lining. An index above 30% is related to infertility.
FertilitySmarts explains DNA Fragmentation Index (DFI)
A semen analysis is a common test that can evaluate the number of sperm (concentration), the shape of sperm (morphology), and the movement (motility). It is possible that semen that has no abnormal findings in a semen analysis may still be unable to fertilize an egg due to a high percentage of sperm with DNA fragmentation.
The most common test for DNA fragmentation is called the sperm chromatin structure assay (SCSA) is used. The SCSA is a specialized test that places the sperm through certain stressors that breakdown the DNA to determine how well the sperm can repair the broken DNA. The higher the DFI, the less likely the sperm will be able to fertilize an egg.
There are multiple causes that may lead to a higher DFI, including varicocele, smoking, age, obesity, testicular cancer, and infection. Some of these factors can be controlled and may lead to a reduction in the DFI and increase male fertility.