Abstract

The SCSA® test assesses DNA fragmentation using established methods that
are supported by 25 years of research published in peer reviewed journals. These
and ongoing studies indicate that sperm with elevated DNA fragmentation, as
measured by the SCSA® test, have a lower probability of supporting a successful
pregnancy.

The severity of male factors should be assessed prior to determining the appropriate
treatment of couples presenting with infertility. The most common screening
for male factors in the infertility evaluation is conventional semen analysis,
which measures basic parameters including sperm concentration, motility and
morphology. Severe and irreversible male factors are often treated successfully
with intracytoplasmic sperm injection (ICSI) by injecting individual sperm into
the egg cytoplasm.

ICSI bypasses all requirements of normal sperm motility and sperm/oocyte oolemma
interaction. The only requirement for fertilization and early embryonic development
is oocyte activation and adequate DNA integrity. Thus, a test of DNA integrity
is very helpful in deciding which couple would most likely benefit from ICSI
and which might be advised to consider other options such as donor insemination
due to decreased odds for pregnancy with the male partner's sperm. Table I lists
conditions when DNA fragmentation testing could potentially benefit a couple.

The Sperm Chromatin Structure Assay (SCSA®) test measures the percent
of sperm in a semen sample that has fragmented DNA as well as the extent of
DNA fragmentation. In the SCSA® test, sperm with very low levels of fragmentation
fluoresce green, while sperm with moderate to high levels of fragmentation fluoresce
red. The flow cytometer measures the ratio of red to green fluorescence in each
of 5000 sperm. The percent of sperm with DNA fragmentation (red fluorescence)
is expressed as the DNA Fragmentation Index (DFI; Evenson et al 2002).

The SCSA® test is a rapid, consistent, statistically robust test providing
evidence for the relationship between sperm nuclear DNA fragmentation and function
(Evenson et al 1991). DFI statistically derived thresholds of 0-15%, 16-29%,
and >30% correlate with high, moderate, and low in vivo fertility potential,
respectively (Evenson et al 1999). Specifically, if the DFI is >30%, there
is a significantly greater risk for infertility (Evenson et al 1999, Evenson
et al 2002, Spano et al 2002).

A preliminary study of in vitro fertility found a similar DFI threshold (>27%)
to be predictive of a negative pregnancy outcome following ART (conventional
in vitro fertilization and ICSI; Larson et al 2000). Larger subsequent studies
including hundreds of infertile couples have validated that a man with >30%
DFI has a significantly greater risk for infertility even with ART. Although
this risk is influenced by a myriad of potential sources (maternal age, clinical
techniques, etc.), exceeding this DFI threshold appears to decrease pregnancy
rates by 50% upwards to 100% in some studies (Larson et al 2002a, Selah et al
2002, Virro et al, submitted).

SCSA® test parameters are weakly correlated with conventional examinations
of sperm concentration, motility, and morphology (Evenson et al 1991, 1999).
Semen samples with normal conventional parameters may have very poor DNA quality
that contributes to infertility. Therefore, the SCSA® test offers additional
clinical information not provided by conventional semen analysis alone.

Twelve couples with multiple failed ART cycles and no known male factors progressed
to therapeutic donor insemination following discussion of their abnormal SCSA®
test results (>30%). Nine of these couples conceived within 3 cycles of donor
insemination after years of infertility (Virro et al, submitted). Insight into
DNA integrity provided by the SCSA® test appears to offer an explanation
for these previous failures.

Age (Evenson et al 2002a, Spano et al, 1998), long periods of abstinence (Spano
et al, 1998), high fever (Evenson et al, 2000), and leukocytospermia (Alvarez
et al, 2002) appear to be related to a significant increase in sperm DNA fragmentation.
Data also show that exposure to environmental stresses, some prescription drugs
(Evenson et al, 1999), pollutants (Selevan et al, 2000) or cigarette smoking
(Spano et al, 1998; Potts et al, 1999) may have a detrimental effect on sperm
DNA.

DNA fragmentation by the SCSA® test reflects the quality of sperm that
have just undergone maturation in the male reproductive tract. While an excellent-quality
sample is likely reflective of previous and future quality, poor DNA quality
may be transient due to high fever, medications, physical or mental stress,
or other unidentified conditions. Therefore, if SCSA® test results are poor,
it is necessary to question the patient as to whether he has been exposed to
conditions that may negatively affect sperm quality, correct these conditions
if possible, and repeat the SCSA® test in 2 to 3 months.

The SCSA® test is a rapid, sensitive, unbiased, quantitative assessment
of sperm DNA fragmentation that independently predicts natural and in vitro
infertility. This prognostic information provides a significant medical, emotional,
and financial benefit to couples considering ART, donor sperm or adoption.

Table I. Conditions Indicating SCSA® Testing

• Unexplained Infertility


• Persistent Infertility after Treatment of Female


• Recurrent Miscarriage


• Prior to Assisted Reproductive Technologies


• Cancer in Male: Before and after Treatment


• Abnormal Semen Analysis


• Advancing Male Age (> 50 years)

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