The Sperm Chromatin Structure Assay (SCSA?) Test: Evaluation of the Infertile Couple.
Donald P. Evenson, Ph.D., HCLD
South Dakota State University and President and Director of SCSA? Diagnostics, Inc.08 January 2003
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
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 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)
Alvarez, JG, Sharma RK, Ollero M, Saleh RA, Lopez MC, Thomas AJ, Evenson
DP, Agarwal AA. (2002) Increased DNA damage in sperm from leukocytospermic
semen samples as determined by the sperm chromatin structure assay. Fertility
and Sterility 78;319-329.
Evenson DP, Larson KL, Jost LK. (2002) The sperm chromatin
structure assay (SCSA®): clinical use for detecting sperm DNA fragmentation
related to male infertility and comparisons with other techniques. Andrology
Lab Corner. Journal of Andrology 23;25-43.
Evenson D, Larson K, Jost L, Virro M, DeJonge C, Brannian J. (2002a)
Relationship between age of man, sperm DNA fragmentation and infertility. April
2002, Seattle Washington. American Society of Andrology.
Evenson DP, Jost LK, Corzett M, Balhorn R. (2000) Effect of
elevated body temperature on human sperm chromatin structure. Journal of
Evenson DP, Jost LK, Marshall D, Zinaman MJ, Clegg E, Purvis K, De
Angelis P, Claussen, OP. (1999) Utility of the sperm chromatin structure
assay as a diagnostic tool in the human fertility clinic. Human Reproduction
Evenson, DP, Jost LK, Baer RK, Turner T, Schrader S. (1991)
Individuality of DNA denaturation patterns in human sperm as measured by the
sperm chromatin structure assay. Reproductive Toxicology 5;115-125.
Larson-Cook K, Brannian J, Hansen K, Jost L, Evenson D. (2002a)
Relationship between assisted reproductive techniques (ART) outcomes and DNA
fragmentation (DFI) as measured by the Sperm Chromatin Structure Assay (SCSA).
American Society for Reproductive Medicine. Seattle Oct 12-17. #100777.
Larson KL, DeJonge CJ, Barnes AM, Jost LK, Evenson DP. (2000)
Relationship of assisted reproductive technique (ART) outcomes with sperm chromatin
integrity and maturity as measures by the sperm chromatin structure assay (SCSA).
Human Reproduction 15;1717-1722.
Potts RJ, Newbury CJ, Smith G, Notarianni LJ, Jefferies TM. (1999)
Sperm chromatin changes associated with male smoking. Mutation Research
Saleh RA, Agarwal A, Nelson DR, Nada EA, El-Tonsy MH, Alvarez JG, Thomas
AJ Jr, Sharma RK. (2002) Increased sperm nuclear DNA damage in normozoospermic
infertile men: a prospective study. Fertility and Sterility 78(2):313-8.
Selevan SG, Borkovec L, Slott VL, Zudova Z, Rubes J, Evenson DP, Perreault
SD. (2000) Semen quality and reproductive health of young Czech men
exposed to seasonal air pollution. Environmental Health Perspectives 108;887-94.
Spano M, Bonde JP, Hjollund HI, Kolstad HA, Cordelli E, Leter G. (2002)
Sperm chromatin damage impairs human fertility. The Danish First Pregnancy Planner
Study Team. Fertility and Sterility 73;43-50.
Spano M, Kolstad AH, Larson SB, Cordelli E, Leter G, Giwercman A, Bonde
JP. (1998) The applicability of the flow cytometric sperm chromatin
structure assay in epidemiological studies. Human Reproduction 1998;2495-505.
Virro MR, Evenson DP. (submitted) Sperm Chromatin Structure
Assay (SCSA®) related to blastocyst rate, pregnancy rate and spontaneous
abortion in IVF and ICSI cycles. Fertility and Sterility.