Sperm Chromatin Structure Assay (SCSA)

Routine male fertility testing (semen analysis) assesses a number of aspects of male fertility such as sperm morphology, count and motility. However, fertility can also be assessed by measuring the amount of damage to the genetic material carried by sperm (DNA or DNA fragmentation). The level of sperm DNA fragmentation has only a minor association with parameters measured by a routine semen analysis, and so it has little to do with the shape of the sperm or whether the sperm are moving. Men with an otherwise normal semen analysis can have a high degree of DNA damage and men with a very "abnormal" semen analysis can have very little DNA damage. This may explain at least in part why a routine semen analysis is of limited predictive value in many cases for male fertility.

The degree of DNA fragmentation can be associated with reduced ability of sperm to result in a healthy pregnancy no matter what technology is used to fertilize the egg such as insemination (IUI), IVF or ICSI. Sperm with high DNA fragmentation may fertilize an egg but embryo development may be compromised before implantation or may even initiate a pregnancy but with a significantly higher likelihood that it will result in miscarriage. By testing for sperm DNA fragmentation, some cases of otherwise "unexplained" infertility may be explained. This information can be helpful in providing evidence for a need to address a man's lifestyle such as being overweight or smoking.

How is an SCSA test performed?

There are a number of ways to test for sperm DNA fragmentation; the most commonly used is called the Sperm Chromatin Structure Assay or SCSA. The semen sample is frozen and shipped in a liquid nitrogen container to the SCSA laboratory, where the sperm are then thawed out and subjected to stress (a low pH). The sperm are then labelled with a special orange coloured dye that only attaches to the ends of broken DNA within the sperm. If the DNA is intact then no dye will attach to the sperm. A machine called a flow cytometer is used to analyze a large number of sperm from the sample. Sperm are passed by a beam of light that hits the dye inside the sperm cell and the reflected light is either orange (damaged sperm DNA) or green (normal sperm DNA). A computer then counts the percentage of green versus orange-labelled sperm.

What are the causes of Increased Sperm DNA Fragmentation?

The causes of high DNA fragmentation include exposure to chemicals/toxins, infection, smoking, and perhaps a varicocoele.

Can an abnormal SCSA test result be treated?

Sperm DNA fragmentation can change with time and it can be improved in many cases by lifestyle changes. Recent studies have demonstrated that the incidence of DNA fragmentation in ejaculated spermatozoa can be reduced by oral treatment with two antioxidants, vitamins C and E. In addition, there is some evidence that if a man's vitamin D levels are low then oral vitamin D therapy can improve sperm motility. A further option for couples undergoing IVF is to undergo HA-ICSI in order to have a higher chance of selecting sperm for fertilization that have intact DNA.

How much does the test cost and how long will it take?

An SCSA test costs $258 of which approximately $40 to $50 is claimable from Medicare. The results are usually available within seven days of the semen sample reaching the SCSA laboratory.