MALE
INFERTILITY
Abnormal semen analyses are found in one third of infertile
couples. In most cases, no clear cause is identified for
subfertile men, as the regulation of sperm
production in the testicle is poorly understood. Sperm is
made by seminiferous tubules in the testicle. Testicular
Leydig cells make testosterone. Almost all men with abnormal
semen analyses have normal testosterone production. Therefore,
a semen
analysis is the only way to predict male reproductive
potential, and should be one of the first tests performed
on an infertile couple.
The World Health Organization has defined a normal semen
analysis as a volume greater than 2 ccís, sperm count
greater than 20 million/cc., and 50% motility with 30% normal
appearance (morphology). Causes of low semen volume include
incomplete collection, repetitive ejaculations immediately
prior to the semen analysis, and neurologic conditions such
as diabetes and multiple sclerosis.
The cause of a low sperm count has not been well determined.
Men with extremely low sperm counts (less than 1 million/cc.)
may have small deletions in their Y-chromosome, particularly
in the area DAZ gene. If
there is a genetic cause for markedly abnormal semen, ICSI
could pass this condition onto male offspring, requiring
ICSI in a subsequent generation. Conventionally, a normal
sperm count has been defined as greater than 20 million/cc.
In reality, many men between 10-20 million/cc. count have
diminished fertility but are not absolutely infertile.
A man with a normal semen analysis, typically ejaculates
at least 20 million motile sperm into the vagina. The vast
majority of these sperm never get into the cervix or upper
reproductive tract. It has been estimated that several hundred
sperm advance to the fallopian
tube where fertilization
of the egg
occurs. For that reason, low sperm motility is a more significant
predictor of infertility
compared even to low sperm count. The causes of low sperm
motility are not well understood. Sperm is produce on a
two to three month cycle. If a man had a febrile illness,
it is possible that he may have a transiently abnormal sperm
production which reverts back to normal over time as a new
crop of sperm is created.
Sperm are comprised of a head containing an achrosome, which
is important for the sperm burrowing its way through the
egg shell (zona ellucida) of the egg. The sperm head contains
23 chromosomes. Sperm also contain a tail tht is critical
for motility. Abnormalities of sperm appearance (morphology)
are common. In general, unless there are severe defects
of the sperm head, morphology is not a good predictor of
fertility. A very technical analysis of sperm appearance,
called strict criteria, is a good predictor of men who require
ICSI. However, for the vast majority of
patients undergoing a routine semen analysis, morphology
is a poor predictor of fertility.
Most men with mild to moderate decreases in sperm count
and motility can establish pregnancies through the use of
intrauterine
inseminations. A semen specimen can be produced at home,
and transported to the office. In colder seasons, it is
helpful to keep the specimen warm, inside a sock, in your
jacket. The semen is washed with sperm wash media and the
sperm are concentrated. A very thin flexible catheter is
then placed through the woman's cervix into her uterus.
This 30 second painless procedure places all of the motile
sperm at the top of the uterine cavity, close to the entrances
to the fallopian tubes. For men with more severe abnormalities
of sperm motility, count, and morphology, in- vitro fertilization
with ICSI (direct injection of a sperm into an egg) is an
extremely successful therapy. In our experience, pregnancy
rates for conventional IVF and ICSI are equivalent. Consequently,
IVF success rates rest on the woman's age and the quality
and number of her eggs, even in cases of severe male factor
infertility.
The criteria for choosing ICSI over conventional IVF (where
a single egg is surrounded by one hundred thousand motile
sperm) have loosened over time. In general, if male factor
infertility is the reason for proceeding with IVF, ICSI
is invariably used to guarantee fertilization. In cases
that are less clear cut a sperm penetration assay can be
performed prior to the IVF cycle. The man's sperm is mixed
with hamster eggs. If few sperm penetrated into the hamster
eggs, ICSI is indicated.
The complete absence of sperm in the ejaculate is a disturbing
finding. Two causes have been identified. A urologic evaluation
is critical to assess whether there is a structural blockage
(congenital absence of the vas deferens) preventing sperm
getting from the testicle into the ejaculate. Half of the
men with congenital absence of the vas deferens are carriers
for cystic fibrosis. Their wives need to be tested to see
if they too are carriers for cystic fibrosis prior to establishing
a
pregnancy. We have had many successful pregnancies in men
with congenital absence of the vas deferens using in
vitro fertilization. The process is straightforward.
Sperm is extracted from the testicle and each of the woman's
eggs is directly injected (ICSI). The other cause of azospermia
is a lack of sperm production by the testicle. This commonly
is called sertoli only syndrome. A rare man may have a few
sperm in the testicle, but none in his ejaculate. Testicular
biopsy with subsequent ICSI has been successfully performed
in a small group of these patients. The use of donor
sperm is often the procedure of choice in cases of azospermia.
Some men have an overgrowth of veins surrounding the testicle
called a varicocele. Varicoceles are common. Their role
in male infertility is far from clear. While some men do
benefit from varicocele repair, many do not. The emergence
of in vitro fertilization with ICSI as an extraordinarily
successful therapy for male factor infertility has lessened
the role of varicocele repair.
