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Using sperm from the epididymis and testis for ICSI in order to treat patients with obstructive azoospermia is logical, and thus conceptually easy to understand. However, surprisingly, it is possible to find sperm even in patients who have testicular failure (nonobstructive azoospermia) --- even in those men with very small testes. The reason for this is that defects in sperm production are "patchy"--- they do not affect the entire testis uniformly. This means that even if sperm production is absent in a certain area, there may be other areas in the testis where sperm production could be normal (this could be because the genetic defect that causes abnormal spermatogenesis may be "leaky"). Since such few sperm are needed for ICSI, we can find enough sperm in over 50 per cent of patients with testicular failure, even if their testes are as small as a peanut!
However, while finding sperm is quite easy in men with obstructive azoospermia (since their testes are functioning normally), patients with nonobstructive azoospermia (testicular failure) can be very challenging. Often, sperm production in these men is sparse, and multiple sites in the testis may need to be sampled before being able to find sperm. Performing multiple tiny micro biopsies can do this, and this is called TESE or testicular sperm extraction. (One of our patients suggested that we call this procedure TSEICSI - which stands for testicular sperm extraction with ICSI, and pronounce it as "sexy"!) This can be done through the needle, or as an open procedure performed under direct vision through a tiny skin incision under local anesthesia and sedation. Finding sperm in the testicular tissue can be a laborious process, depending on the degree of sperm production, and testicular sperm are hard to work with in the laboratory. For men with nonobstructive azoopsermia, we usually perform the TESE the day prior to egg retrieval, because culturing the testicular tissue in the incubator for 24 hours helps the sperm to acquire motility, which makes them easier to work with. In case no sperm are found, either the couple decides to cancel the egg retrieval and abandon the cycle, or to go ahead with using donor sperm for IVF, as a backup option.
In patients in whom surgery needs to be performed in order to recover testicular or epididymal sperm, it is now possible to freeze the excess sperm. These sperm can then be thawed and used in future cycles if needed, thus sparing the patient the need for repeated surgery for sperm retrieval.
Once eggs and sperm have been collected, the actual process of injecting a single sperm into the egg is carried out in a laboratory. The injection is performed on a heating stage, on a specialized inverted microscope (which allows one to magnify details up to 400 times) equipped with Hoffman modulation contrast optics (which enhance "optical contrast", so that the details of the egg can be visualized easily). Using specialized micromanipulators, which allow one to execute very fine movements, provides the precise control that is needed for microinjection.
© Dr. Aniruddha Malpani and Dr. Anjali Malpani www.drmalpani.com
Credits: How to Have a Baby: Overcoming Infertility
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