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The TUNEL test is a test that looks at DNA damage, or fragmentation, within sperm heads. Increased DNA fragmentation of sperm has been linked to recurrent miscarriage and unexplained infertility.

What is sperm DNA fragmentation?

DNA is the hereditary material in humans that consists of two long polymers of simple units with backbones — DNA strands. The information in DNA is stored as a code made up of four types of molecules called bases, which are attached to the DNA strands. The order, or sequence, of these bases determines the information available for building and maintaining an organism. DNA fragmentation occurs when there is an alteration to the bases or a physical break in one or both of the DNA strands.

Causes of Sperm DNA Fragmentation

The main contributor to DNA fragmentation is the cumulative damage of free radicals not adequately neutralised by antioxidants, called oxidative stress. Sperm DNA fragmentation is associated with drug use, cigarette smoking, exposure to environmental and occupational pollutants, advanced age, varicocele, elevated testicular temperature (laptop computers, hot tubs), and poor diet.


What is involved in a TUNEL test?

This procedure involves isolating swimming (motile) sperm, therefore a fresh semen sample is required to carry out this test. Our scientists will wash the sperm and prepare slides to accurately assess the DNA fragmentation within sperm heads using a high power magnification microscope. This is a specialised test where results can take up to a week to be reported.