Low or no sperm count used to be the end of the fertility road - but not any longer, says Dr Gillian Lockwood

Before 1995, men with low or no sperm counts had no prospect of having their own genetic baby. However, the development of ICSI (intra-cytoplasmic sperm injection - in which individual healthy sperm are micro-injected into eggs obtained during an IVF cycle) transformed the fertility prospects for thousands of couples with severe male-factor infertility.

Although many men may suffer from azoospermia (absence of sperm in the ejaculate), the majority will produce viable sperm in their testes. The challenge for the fertility clinician is to find the sperm so that the embryologist can perform ICSI. (Unfortunately, even ICSI can't overcome complete azoospermia and these couples still need to use donor sperm.)

New hope
Progress with surgical sperm retrieval began with long and complex operations requiring general anaesthesia such as MESA (micro-epididymal sperm aspiration) or open biopsy. Today, outpatient procedures - such as PESA (percutaneous epididymal sperm aspiration) and TESE (testicular sperm extraction) -- have simplified the sperm retrieval process.

A further advance pioneered in the UK, at Midland Fertility Services, was the discovery that sperm-containing tissue obtained at PESA or TESE could be frozen without loss of viability. This meant that the process of sperm retrieval could be separated from ovarian stimulation for IVF. You could start your IVF drugs secure in the knowledge that your partner's sperm could be defrosted and made available on the right day to fertilise the eggs.

What causes azoospermia?
Men may be azoospermic for many reasons. Sometimes the cause is obvious - a vasectomy that couldn't be reversed, for example. Sometimes the cause may be CBAVD (congenital bilateral absence of the vas deferens - a genetic problem that can be associated with cystic fibrosis).

Incomplete descent of the testes into the scrotum, surgery, trauma or infection may block the delicate tubes leading from the testes, or the man may have early testicular failure (a premature andropause) and only be producing small quantities of sperm.

Tests for success
In all cases, it is vital to know whether sperm is being produced in the testes. That way, the man is not subjected to a surgical procedure when there is no hope of finding any sperm. The couple can also be appropriately counselled about their chance of success with ICSI.

About five years ago, a new endocrine hormone was identified called inhibin B. In women, inhibin B is a marker of ovarian reserve, but in fertile males it is produced by the Sertoli cells (the site of sperm production). Other 'male' hormones such as testosterone and follicle-stimulating hormone (FSH) are also useful guides to an azoospermic man's fertility potential. It has been found (after measuring the inhibin B levels in over 100 azoospermic men undergoing PESA or TESE) that the level of inhibin B accurately predicts whether or not viable sperm will be found.

Irrespective of the cause of the azoospermia and the level of FSH, it has been found that if the man's inhibin B level is greater than 80pg/ml, sperm will be retrieved at PESA, TESE or open biopsy. All azoospermic men are now routinely offered the inhibin B test at MFS (and all men would rather have a blood test than a fruitless testicular biopsy!).