A recent history of proven fertility (having achieved a pregnancy)
or a history of fertilization at In Vitro Fertilization are powerful
indications that the sperm can act (to fertilize a human egg)
The semen analysis is the best screening
lab test that we currently have available for the evaluation of
sperm. The three most commonly used parameters of the test are
the sperm concentration (how many sperm are present per unit volume),
the morphology (percentage of the sperm with a normal shape) and
the motility (percentage of sperm that are moving, occasionally
with some further characterization of the quality of motion).
A single isolated poor quality semen analysis is not necessarily
ominous. The same man may produce two samples within the same
week under ideal conditions for analysis and the quality of the
sperm can be very different. Research has also demonstrated that
the same sperm sample tested at multiple labs yields large variations
in all of the parameters including the concentration. Therefore,
the initial evaluation of the semen should most likely include
two independently timed semen analyses (within 1-2 weeks) if the
initial analysis is abnormal. If the initial semen analysis is
normal then there is no reason to repeat it.
Spermatogenesis, spermiogenesis and the storage of sperm in the
epididymis occur over relatively long periods of time. The sperm
produced by ejaculation today started its course of development
about 3 months ago. Thus, if the repeat semen analysis confirms
an abnormal result then a transient insult (such as a viral infection
or fever) can be essentially ruled out by checking a semen sample
a few months later to allow for submission of a "new"
sample (one created under different and non-overlapping production
conditions). If the initial analysis is very abnormal (such as
azoospermia or severe oligospermia then treatment options do not
need to be delayed in order to reevaluate in 3 months).
Once there is a relatively consistent set of semen analyses, the
question of interpretation becomes important. Unfortunately, there
are no universally accepted reference ranges for semen analysis.
In Monmouth and Ocean counties of New Jersey, I am familiar with
the values considered normal for semen analysis at 7 different
medical centers. The normal ranges in these closely spaced medical
centers vary considerably from one another. Thus, if the same
semen sample readings are reported by 2 different local medical
centers one center may report the analysis as normal while the
other might report it as abnormal. This can lead to confusion
and frustration. I prefer to use the World Health Organization
(WHO) guidelines and reference ranges for normality since they
are also supported by the American Society for Reproductive Medicine.
The semen analysis can provide a great deal of information. It
should be routinely ordered during the evaluation for all infertile
The collection process of the sample is important. Basic instructions
- Call the office to schedule the semen analysis to avoid delays
in evaluating the sample.
- Sexual abstinence for at least 2 days but not longer than
7 days before obtaining the sample.
- Obtain the sample by manual masturbation only. There should
be no vaginal, oral or anal contact with the penis since this
may produce a poor result. Avoid using lubricants since they may
be toxic to sperm.
- Collect the entire semen specimen in a warm, clean, wide mouthed,
plastic or glass container. It is very important to obtain the
whole specimen. Also, please check to be sure the top is properly
fastened prior to transport to prevent spillage.
- Label the specimen with both names (of partners), the period
of abstinence, the date, and the time of collection.
- The specimen must arrive at the lab within about 1 hour of
collection and should be protected from temperature extremes (cold
The semen analysis supported by the WHO includes the following
* volume: normal is 2-5 ml. Less than 2 ml might be due
to incomplete collection. Historically, a low volume has been
thought to be associated with decreased numbers of sperm able
to swim into the cervical mucus. This has recently been questioned.
A large volume of sperm may result in low concentration (since
the total number of ejaculated sperm are in a larger volume).
Thus, there might be decreased numbers of sperm able to move into
the cervical mucus at the sperm-mucus interface.
* pH: normal is 7.2-7.8, which is alkaline. A higher pH
is associated with an infection in the prostate. The pH of the
vaginal tract is low (acidic), about 3-4, while the pH of the
pre-ovulatory cervical mucus is generally greater than 7. Sperm
in the vagina does not last longer than 1-2 hours. In the pre-ovulatory
mucus sperm can often survive for 2 or more days since the pH
and other mucus characteristics are friendly to sperm.
* concentration: greater than 20 million per milliliter
is normal. There have been several recent articles claiming to
document a decrease in the sperm counts of men. This normal value
was determined in the early 1950s and has not been changed since
that time. Many experts in male factor infertility now believe
that only very low concentrations, such as 5-10 million per milliliter,
accurately reflect a decrease in concentration that is important
for fertility. Since the low normal volume is 2 milliliters, a
normal number of sperm per ejaculate is 40 million sperm (20 million
per milliliter times 2 milliliters).
* motility and progression: the WHO divides motility into
nonmotile, nonprogressive but moving, slow but linear or nonlinear,
and rapid linear movement. Greater than 50% of sperm showing either
slow but linear, nonlinear or rapid linear movement is normal.
Also, greater than 25% showing rapid linear movement is normal.
Poor motility may be able to be enhanced using chemical agents
similar in structure and function to caffeine.
* morphology: greater than 30% normal forms is normal.
Until a few years ago, the WHO required 50% normal forms to be
considered normal. A "strict morphology" which excludes
any sperm with even minor abnormalities from being considered
normal was developed by a researcher named Thinus F. Kruger from
South Africa while working with the infertility group at the Jones
Institute for Reproductive Medicine in Norfolk Virginia. Using
the strict morphology if greater than 14% normal forms are identified
then this is associated with a normal fertilization rate (70-80%)
at In Vitro Fertilization, if 4-14% normal forms are identified
there is a proportionate decrease in fertilization, and if less
than 4% normal forms are identified then there is only a poor
(7-8%) fertilization rate at IVF. Although advocates of the strict
morphology claim it to have good predictive value in terms of
fertilization at IVF, it has not been widely accepted by the infertility
community as a standard test (at least in 1997).
* round cells or white blood cells (WBCs): a count of greater
than 1 million per milliliter is abnormal. It is not possible
to distinguish immature sperm from WBCs without staining the cells,
therefore, most labs report out the concentration of "round
cells" with the understanding that the identity of these
cells has not been determined. If these cells represent WBCs and
if these cells are persistently elevated in concentration, then
it suggests an infection. The usual location of these asymptomatic
infections is the prostate gland. These infections often are difficult
to treat since the blood supply to the prostate is poor, so antibiotics
are usually given for several weeks.
* agglutination of sperm (when motile sperm stick to one
another), appearance of the semen (color, time to liquefaction,
presence of streaks or grains), consistency (an estimate of viscosity),
and antibody testing are other components of the WHO's basic semen
Semen analysis is not a sperm function test. A good sperm function
test with high positive predictive value and low negative predictive
value would be useful. Unfortunately, there are no really good
sperm function tests available.
The semen analysis tells you that there is what seems to be a
reasonable number of sperm, the sperm appear to be moving well
and they are normally shaped. The strict morphology of Kruger
approaches a sperm function test but has not been widely accepted
A sperm function test would be able to identify sperm that is
able to "do its job," which in a reproductive sense
is to fertilize an egg. A great looking sperm that appears to
move well on semen analysis may not fertilize an egg while another
less attractive sperm may reliably be able to accomplish fertilization.
The sperm function test should use fertilization or pregnancy
to judge outcome.
The sperm penetration assay (SPA) has been proposed as
a sperm function test, and in fact, was widely accepted until
recently. The SPA determines the frequency with which a "sample
sperm" penetrates hamster eggs compared to the frequency
of fertilization with "known fertile sperm." To allow
the eggs to be fertilized by another species' sperm the outer
shell (zona pellucida) of the egg is removed by chemical digestion
prior to the test. Additionally, the sperm must undergo the process
of capacitation which enables it to undergo the acrosome reaction.
In the standard SPA, 16% of men with no fertilization of hamster
eggs have been reported to achieve human pregnancies. This high
false negative rate is one factor that has led to the decline
in popularity of this test. In an attempt to reduce the false
negative rate sample sperm and donor sperm are often pre-treated
with one of a number of chemical agents (follicular fluid, test
yolk buffer, calcium ionophore) that enhance capacitation. Ongoing
problems with the test such as large changes in assay results
following small changes in assay conditions have limited its acceptance.
Less popular sperm function tests have included
* (1) the hemizona assay test:
Human egg "shells" or zona pellucidae are divided into
halves and the binding of sample sperm is compared to the binding
of known fertile sperm on zona from the same egg. The almost complete
lack of available fresh human eggs for experimentation has largely
been responsible for the lack of acceptance of this test
* (2) the in vitro sperm penetration of mucus test:
Sperm is placed adjacent to mucus on a microscope slide and the
progression into the mucus is monitored. Bovine (cow) cervical
mucus is available and has been proposed to allow standardization.
This test became more popular as a means of assessing abnormal
post coital tests prior to the wide acceptance of intrauterine
* (3) sperm motility using sperm quality analyzers:
Electro-optical techniques and computer assisted techniques of
assessing sperm motility have been reported to correlate to fertilization
rates at IVF. Lateral head displacement is thought to be a good
prognostic indicator. The general lack of standardization and
interpretation of these interesting tests has restricted their
use largely to experimental settings
* (4) the hypoosmotic swelling test:
Placement of sample sperm into a solution (of fructose or sodium
citrate) of low concentration (hypoosmotic) results in the swelling
and coiling of the sperm's tail as it takes up water. Due to the
lack of standardization and predictive value of this test it has
remained of low clinical value
* (5) seminal ATP concentration:
The adenosine triphosphate level in sperm has been proposed as
a discriminator of fertile sperm. A large multicenter WHO study
failed to find a reasonable predictive value for semen ATP concentrations
when there was no recognized female factor and the sperm concentration
was greater than 20 million per milliliter
* (6) acrosome reaction:
The acrosome reaction occurs at or near the egg's shell (zona
pellucida) and examination of sperm samples to determine the percentage
of sperm having undergone this reaction has been suggested as
a screen for sperm function. In reports correlating IVF fertilization
with the initiation of the acrosome reaction only very small differences
in the percentage of acrosome reacted sperm was seen between groups
with differing fertilization rates. This lack of predictive value
and the expensive nature of this specialized test have limited
its use clinically
* (7) acrosin measurements:
Acrosin is a proteolytic enzyme within the acrosome of the sperm
head and is possibly important in aiding the sperm through the
zona pellucida. A low level of acrosin has been correlated with
deminished fertility. Research on this test is active and hopefully
will yield a useful test in the next few years.
I restrict my testing for male factor infertility to the semen
analysis. Having an experienced person (infertility specialist,
urologist with a commitment to male factor infertility, andrologist)
perform the semen analysis can make a difference and is often