Azoospermia is the absence of sperm in the semen or
failure in the formation of sperm. May occur as a result of primary
testicular failure, obstruction or prior vasectomy. Azoospermia means
complete infertility. Common Causes of azoospermia include:
Primary testicular failure
This may be due to genetic defects, undescended testicles,
testicular injury or mumps in puberty. Often, the cause is unknown. Patients
with primary testicular failure usually have small testes and smooth and a
grossly elevated plasma FSH. Although undescended testicles can be
surgically corrected, the probability of restoring fertility is remote.
Obstruction
This is the second most important cause of azoospermia. It
is sometimes appropriate for surgery and surgical exploration may be
performed in patients with normal-sized testes and normal FSH. The results
of surgery depend on the location of the block and there is at least a
success rate of 50% in those patients with an obstruction in the tail of the
epididymis due to gonorrhea.
Sexually transmitted diseases can cause
epididymitis and establish a blockade of the tube, resulting in permanent
azoospermia. Obstructive azoospermia may also be due to agenesis (absence)
of the epididymis and other parts of the tubular system, including the vas
deferens. Some of these cases appear to be genetic in origin. Congenital
bilateral agenesis of the vas deferens is found in most patients with cystic
fibrosis. It has been shown that mutations of the cystic fibrosis gene may
be present in at least two-thirds of men with bilateral agenesis of vas
deferens isolated, with no other symptoms of cystic fibrosis. This means
that men with congenital absence of vas deferens that produce sperm, and
thus have indications for ART should be counselled regarding the risk of any
of their children likely to have cystic fibrosis.
Prior Vasectomy
This is a question increasingly common in azoospermia in
Western countries and in countries such as India, which is a favourite method
of contraception.
Absence of germ cells
In many men with azoospermia, the seminiferous tubules
contain only Sertoli cells. This can result from numerous causes, including
the use of cytotoxic drugs, irradiation or due to factors present during
fetal life. However, in most cases, the aetiology is unknown.
