Sperm may be retrieved from two main sites:
- the epididymis, the structure beside the testis where sperm are stored and mature before ejaculation,
- the testis, the tissue in which sperm are produced.
The choice of site depends mainly on whether the azoospermia is obstructive or non-obstructive.
Epididymal sperm-retrieval techniques
PESA — Percutaneous Epididymal Sperm Aspiration
Intrauterine PESA is one of the simplest sperm-retrieval techniques. It is usually performed under local anaesthesia and uses a fine needle and syringe to aspirate fluid from the epididymis.
This technique is used mainly for obstructive azoospermia, where sperm production in the testes is preserved but a blockage prevents sperm from reaching the ejaculate.
PESA is minimally invasive and quick, and may be suitable in selected cases. It is not always feasible or successful, however, and another technique may sometimes be required.
MESA — Microsurgical Epididymal Sperm Aspiration
Intrauterine MESA is a specialised microsurgical technique in which the epididymis is viewed directly under a microscope to collect sperm precisely.
The procedure requires an operating theatre and is usually performed under general anaesthesia. It may be used when percutaneous aspiration is not feasible, after an unsuccessful PESA attempt, or when a more targeted approach is needed.
In selected cases, a microsurgical approach may also assist in assessing or correcting an obstruction, depending on the findings.
Testicular sperm-retrieval techniques
Micro-TESE — Microdissection Testicular Sperm Extraction
Intrauterine Micro-TESE is a specialised technique for retrieving sperm from the testis. It is used mainly in non-obstructive azoospermia, where sperm production is severely reduced or limited to small areas of testicular tissue.
The procedure is performed under general anaesthesia. Using an operating microscope, the urologist examines the testicular tissue and takes small samples from areas most likely to contain sperm.
The samples are examined in the laboratory to identify even very small numbers of sperm that may be suitable for ICSI.
Micro-TESE is more invasive than other techniques, but it is an important option in difficult cases of non-obstructive azoospermia where sperm retrieval requires specialist expertise.
When is sperm retrieval planned?
Sperm retrieval may be planned in two main ways.
In many cases, retrieval is performed in advance. If sperm are found, they can be frozen for future use in an IVF cycle.
In other cases, retrieval may be coordinated with the woman’s ovarian stimulation and performed on the day of egg collection, with the surgical and urology teams available when the eggs are collected.
The choice between fresh and frozen sperm depends on the type of azoospermia, the expected number and quality of sperm retrieved, and the overall treatment plan.
Frozen sperm can be effective, but in some cases of non-obstructive azoospermia only very small numbers are retrieved and some may not survive freezing and warming. Planning is therefore essential: eggs may be collected on the same day, or previously frozen eggs may be warmed if sperm are successfully retrieved.
