For most of human history, fertilisation of a single egg produced by the female partner involved a swimming race between millions of sperm. The single winning sperm was the one that entered the egg first. The modern infertility treatments intracytoplasmic sperm injection (ICSI) and in vitro fertilisation (IVF) now make it possible to extract a single sperm and use it to directly fertilise an egg. The latest surgical sperm retrieval techniques combined with ICSI and IVF also mean that infertility can be overcome even in men who produce hardly any sperm.
A low sperm count is a common cause of male infertility but if a man produces even the tiniest number of sperm in his semen, these can be collected fairly easily. Men who ejaculate no sperm, because of blocked tubes in their testes, or because of a genetic condition that prevents their sperm being released, require some form of surgical sperm retrieval to enable intracytoplasmic sperm injection to take place.
The main methods of surgical sperm retrieval available include:
Which method is used depends on the nature of the problem in the male partner, which needs to be explored carefully first.
A man that produces no sperm in his semen is said to have azoospermia. This may be because of a blockage in one of the tubes that carry sperm from the areas of the testes where they are produced, out to the penis during ejaculation. Obstructive azoospermia can be caused by testicular cancer, as the tumour presses on the vas deferens. This type of cancer is common in young men and can be treated successfully. It can, however, lead to infertility, so surgical sperm retrieval may be performed to store some sperm before treatment begins.
Other conditions cause non-obstructive azoospermia, including having an abnormal cystic fibrosis gene. Men with this condition may not show all the symptoms, but they often have no vas deferens. Surgical sperm retrieval is possible but there is a 50:50 chance that the embryos produced by subsequent ICSI and IVF will have the same genetic abnormality. Options then include using a sperm donor and intrauterine insemination (IUI) or IVF, or having pre-implantation genetic diagnosis (PGD) performed on the embryos to select ones that carry the normal gene.
If the problem that underlies poor sperm production is physical rather than genetic, or if a couple wants to have children after the male partner has had a vasectomy that cannot be reversed, surgical sperm retrieval can go ahead.
When the release of sperm is prevented by a blockage in the vas deferens, or by a vasectomy, several techniques can be used to retrieve the large numbers of sperm that remain inside the testes. The first three involve aspirating sperm using needles or tubes placed through the skin of the testis and are carried out under local anaesthetic. The fourth requires open surgical sperm retrieval and is usually carried out under general anaesthetic.
Some small studies have been done to compare success rates after the different types of surgical sperm retrieval. These concluded that MESA gives the highest number of sperm, with a hundred times more sperm being recovered compared to TESA and perc biopsy. MESA also produced sperm that were better swimmers and therefore more useful for infertility treatments, including IVF and ICSI.
Men who have no sperm in their semen, despite having clear tubes in their testicles, usually have a problem with the process of sperm production. It is unlikely that sperm are present in large numbers, so the surgical sperm retrieval techniques required are more invasive.
Evidence is still accumulating because all of these infertility treatments are relatively new, but one of the most successful combinations appears to be MESA followed by ICSI, which has reported fertilisation and pregnancy rates between 45 % and 52 %.
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