Sperm is produced in the testicles and carried to the penis through the tubes which are known as the epididymis and the vas deferens.
When it is not possible for the sperm to travel beyond the testicles to reach the penis for ejaculation, then sperm can be retrieved by two different methods: TESE (testicular sperm extraction) and PESA (percutaneous epididymal sperm aspiration).
PESA is a minimally invasive technique which is used to extract sperm from the epididymis under local anaesthesia with a fine needle. If sperm cannot be retrieved using this method then the patient may have to proceed to TESE which is also a minimally invasive procedure performed under local or general anaesthesia, and is used to extract sperm from the testicles.
Lack of sperm in the ejaculate can occur as a result of various circumstances, for example, when a man is born without a vas deferens, if the ducts areblocked by scarring from a previous infection, or if the man has undergone vasectomy in the past and reversal has failed.
Sperm obtained from either the testicles or the epididymis will usually have poor motility. Therefore, in order to improve the chances of fertilisation the sperm are usually microinjected into each egg by ICSI.