A testis biopsy is done in order to find out whether sperm production in the testis is normal or not. This is the "gold standard" for judging testicular function, since here the testicular tissue is being examined directly. How is a testicular biopsy performed? This is a simple surgical procedure, which can be done under a local anaesthetic, in an operation theatre or even in the doctor's clinic, if it is well equipped. The test takes about 5-10 minutes to be carried out; and a biopsy could be taken from just one testis, or from both testes, depending upon the nature of the problem.

The removed bit of tissue is then placed in a special preservative fluid called Bouin's fluid which is then sent to a pathologist for examination under a microscope after staining.

The biopsy surgery doesn't hurt, because the local anesthetic numbs the tissues. There may be dull ache for a few days after the procedure, but this can be relieved by mild analgesics.

Since testis biopsy is a surgical procedure, most doctors would use it as the last resort when testing the man. If you are advised to have a testis biopsy, ask the doctor how the result will change your treatment (a question you should ask before being subjected to any medical test, in fact!).

The only group of infertile men who should be offered a testis biopsy are those with azoospermia. Men with oligospermia should NOT be subjected to a testis biopsy because the biopsy report is always normal in these men (and this is not surprising - after all, since sperm are present in the semen, they are obviously being produced in the testes!)

Similarly, testis biopsy should NOT be done for men with azoospermia because of hypogonadototropic hypogonadism ( these men have a low FSH level); or men with an absent vas deferens ( a diagnosis which can be confirmed by a simple clinical examination !)

Formerly, when doctors performed a testis biopsy, they would send only one chunk of tissue for testing. However, today we know that a single biopsy may not be representative of the entire testis. Sperm production is not uniformly distributed throughout the testis, especially in men with non-obstructive azoospermia because of testicular failure. The key question we need to answer in these men is : do they have complete testicular failure ( no sperm production at all in the entire testes) ? or partial testicular failure ( sperm being produced in a few areas of the testes, but the amount produced being so little, that they cannot reach the ejaculate, as a result of which the sperm count is zero) ?

This means that in order to get a true picture of sperm production in the testis, the doctor needs to sample at least 4 different areas of the testis, all of which need to be examined.

In the past, a testis biopsy was purely a diagnostic procedure. Today, it is also used to retrieve testicular sperm in order to treat men with severe male factor infertility. These testicular sperm can be used for intracytoplasmic sperm injection (ICSI). Specialised infertility clinics also have the ability to freeze the testicular tissue. This testicular sperm freezing can be very useful, especially in men with small testes, as the biopsy does not need to be repeated again during treatment.

The interpretation
While the biopsy is an easy test to perform, it is difficult to interpret properly, unless done by an expert. The doctor looks for evidence of sperm production in the seminiferous tubules. In some cases, there is no sperm production at all (absent spermatogenesis); or the sperm production is arrested at a particular stage (maturation arrest). This implies testicular failure, which is usually irreversible, and there is no treatment for this malady. The key question is whether there is partial testicular failure; or whether the testicular failure is complete, which is why examining multiple areas of the testes is important. Men with complete testicular failure have no sperm production at all in the entire testes. Men with partial testicular failure will have a few areas of their testes which still produce sperm normally. These sperm can be used for TESE-ICSI treatment. However, their testicular sperm production is so poor , that the testicular sperm do not reach the ejaculate, as a result of which the sperm count is zero.

If, on the other hand, sperm production in the testes is completely normal, and yet there are no sperm in the ejaculated semen, this clearly means that there is a block in the male reproductive tract. This is called obstructive azoospermia, and is the one condition in which a testis biopsy is extremely useful (i.e., in the evaluation of the azoospermic male, to determine if there is a block to sperm transport).

A testis biopsy is often a procedure which is done badly because it is so "minor" so beware! It is preferable that the biopsy be done by a specialist; a poorly done biopsy may make reconstructive surgery on the epididymis more difficult later on, by causing adhesions and fibrosis (scarring). The commonest problem with the biopsy, however, is that the biopsy result is not reported accurately by the pathologist. Interpreting a testis biopsy is difficult and requires special expertise and is not something that the ordinary pathologist does well. You should retrieve and retain your own slides and preserve them carefully. The pathology laboratory can also be instructed to keep the tissue ("blocks") carefully. It is unfortunately common to find that a testis biopsy has to be repeated simply because the first one was done so badly that its results could not be accurately interpreted. It may also be a good idea to get a second specialist's opinion on the testis biopsy slides.