TESA and PESA are surgical techniques developed to retrieve
sperm from azoospermic men who have a complete absence of sperm in their
ejaculate. These men have to have their sperm surgically retrieved from their
testes or epididymis.
TESA is a day case procedure performed under a local anaesthetic
involving a needle biopsy of the testicle in which a sample of tissue is taken
directly from the testes and used to extract sperm for ICSI.
PESA is a day case procedure performed under a local anaesthetic
involving a needle inserted into the epididymis in an effort to locate and
aspirate a pocket of sperm for ICSI.
Sperm of virtually any quality and from any level of the male
reproductive tract can be used to achieve a pregnancy with the
ICSI procedure. The only criterion is that the sperm is alive even
if it is not moving (immotile). Hence, immature sperm extracted from the testes
and epididymis are also capable of achieving a pregnancy.
There is some concern about the safety of the ICSI procedure. It has been
suggested that the rate of major birth defects may be twice as high as in the
background population (7.4% vs.3.8%) There is no apparent reason to suspect
that ICSI technique is
itself harmful (not procedure related). It is possible that the genetic
disorders, which have led to the sperm problem in the father's sperm, may be
passed on to the offspring.
There is an association between the more extreme forms of male infertility and
the following disorders:
Defects in the Y chromosome (the male chromosome) - "Y chromosome
micro-deletion" - occurs in about 5% of men with azoospermia or very
severe oligozoospermia. If severe deletions are present there will be no sperm
in the testes and the only option will be donor insemination or adoption. If
minor defects are present then sperm can be retrieved from the testes and used
for ICSI; however, if a boy
is born he will inherit the same defect and will be infertile.
Abnormalities in the total number of chromosomes can also cause
azoospermia. The commonest problem is Klinefelter's syndrome which occurs 10
times more commonly in azoospermic men as compared to the normal population. In
Klinefelter's syndrome there is an extra X chromosome (the genotype is XXY
instead of the normal XY). These men will have small testes, varying degrees of
androgen deficiency and azoospermia. Surprisingly, in a large number of these
men a few sperm can be found in their small testes. These sperm can be
retrieved by TESA
and used for successful ICSI. Usually these sperm are normal but may sometimes
be abnormal and carry an extra chromosome which would put the child at risk.
Hence, when using these sperm for ICSI it is necessary to do
PGD (Preimplantation Genetic Diagnosis) after the embryo is formed –
this will confirm that the embryo has no genetic defect and the child will be
normal. If no sperm are present the only option is
Cystic fibrosis and Vas Aplasia. Some men are azoospermic because
their vasa deferentia (the tubes that connect the testes to the urethra) are
absent since birth. As a result, even though their testes produce sperm
normally, their semen is very thin and scanty and does not have any sperm. This
condition is called CBAVD – Congenital Bilateral Absence of the Vasa Deferentia
and is due to a genetic defect related to cystic fibrosis. Cystic fibrosis is a
very serious disease that affects the lungs and other organs. However,
there are a wide range of genetic defects associated with the cystic
fibrosis gene. In the mildest form of the genetic defect there is no problem
with the lungs or other organs but the vasa do not develop. Such men can father
a child through the process of
– ICSI. Pregnancy rates with this method are high. The only precaution required
is screening of the wife to make sure that she is not a silent carrier of the
cystic fibrosis gene mutation. If she is normal the child is generally not at
risk of being born with cystic fibrosis. If the wife is a carrier, then her
genetic defect may combine with the husband’s defect and the child may be born
with vas aplasia or cystic fibrosis. Hence, in those cases where both partners
have a cystic fibrosis gene mutation PGD is required to select the normal
embryos during ICSI.
Androgen receptor gene defects. Since the gene is on the X
chromosome the daughters of men who become fathers by ICSI will eventually
carry such defects and the sons of these women would have a fifty percent
chance of being affected.
Hence, before embarking upon the treatment of severe forms of
male factor infertility, it is advisable to have some cytogenetic screening
performed. Incidentally, very subtle compromise in sperm quality are known to
be responsible for a marginally lower embryonic viability rate and a slightly
higher early miscarriage rate.