Percutaneous Epididymal Sperm Aspiration (PESA)
PESA is done under local or general anaesthesia with the specialist inserting a needle attached to a syringe into the epididymis (the tiny collecting tubules next to the testicles), then gently aspirating fluid. The epididymis is the structure into which the sperm first flow after developing and leaving the testicles.
PESA is used for men who have had a prior vasectomy and in those who have a congenital or acquired obstruction of the genital tract such as absence of the vas deferens. The sperm retrieved with this technique can only be used in conjunction with ICSI treatment.
Sperm may not always be obtained with the PESA technique and the specialist may have to perform an open procedure.
Testicular Sperm Aspiration (TESA)
TESA can be used as a diagnostic procedure to detect Azoospermia (medical condition of a man not having sperm in his seminal fluid), or as a procedure to recover sperm from the testicles from men with obstructions or ejaculatory problems that cannot be treated by any other methods.
In the TESA procedure, a very fine needle is passed into the testicles under anaesthetic, and a tiny amount of tubules is removed from the seminiferous tubules (network of tiny tubes inside the testicles where sperm are produced). These tubules are then processed in the laboratory and checked for the presence of sperm, which can either be used to fertilise eggs or frozen.
Sperm retrieved from the seminiferous tubules in a TESA procedure are less mature and less motile than sperm found in ejaculated seminal fluid. As such, ICSI – a specialised form of IVF - is required to achieve fertilisation with TESA sperm.