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 donor insemination.
• 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 PESA – 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.