Sperm can be obtained directly from the testis using testicular biopsy. The most common reason for this procedure to be undertaken is the obstruction to the sperm transport system.
As a result, no sperm are present in the ejaculate, however, large numbers of sperm may still be produced in the testis. This situation can be congenital or can follow scarring and blocking of the fine tubules that lead from the testis as a result of infection or after vasectomy.
In some patients a fine needle biopsy is performed. Local anaesthetic is placed above the testis and as a result, the skin and the testis itself become numb. A fine needle is then placed through the skin into the testis and a small piece of tissue (perhaps the size of half a grain of rice) is removed, or sperm may be removed directly from the epididymis. The embryologist then examines the fine tubes contained in the biopsy sample and removes sperm for the microinjection procedure. The fine needle biopsy takes about fifteen minutes. Occasionally leftover sperm can be frozen and used for subsequent microinjection cycles. Alternatively the biopsy can be performed again. The results of the microinjection procedure using testicular sperm in such cases are good (approximately 25% clinical pregnancy rate per cycle). This procedure performed under local anaesthetic may not be used at all sites.
Another indication for testicular biopsy is in men with severely damaged testis in whom few sperm are produced and none are available in the ejaculate. In this setting a larger biopsy of the testis is performed under a general anaesthetic and in 50% of cases, adequate sperm numbers can be obtained by carefully processing the biopsy tissue to find the small "islands" of sperm production that persist, despite damage elsewhere in the testis. In cases where no sperm are found, couples must consider whether to discard the eggs or use donor sperm.