• Obstructive azoospermia – when reconstruction has failed, or is not possible (e.g. failure of a vasectomy reversal surgery, absence of vas deferens by birth or multiple blocks following tuberculosis), or if the couple chooses ICSI over surgery.
• Non-obstructive azoospermia – in those men who have areas of focal spermatogenesis.
• Failure to ejaculate during an ICSI procedure (if vibrator stimulation fails and electro-ejaculation is not available).
• Total astheno-/necrozoospermia – when all sperm are immotile they may be viable but immotile, or non-viable and hence immotile. In case of viable, non-motile sperm, these can be identified by the hypo-osmotic swelling test and used for ICSI. However, in case of necrozoospermia (non-viable, immotile) it is necessary to use sperm aspirated from the testis since these are usually viable and may sometimes even be motile.
TESA/ TESA – the sperm are retrieved from the testes

Intra-cytoplasmic sperm injection (ICSI) and testicular sperm extraction (TESE) have reduced the need for donor sperm.

Because sperm might be present in some but not all parts of the testes of such men, multiple samplings of the testicular tissue are usually performed to increase the probability of finding sperm in NOA patients.

These samplings can be done by 3 methods: 1) TESE (testicular sperm extraction), which is actually a surgical biopsy of the testis; or 2) TESA (testicular sperm aspiration), which is performed by introducing a needle in the testis and aspirating fluid and tissue with negative pressure.

TESA and TESE procedures can be done for diagnostic purpose or therapeutic.The testicular tissue obtained through TESA/ TESE are analysed for presence of sperm under a high resolution microscope and a part of the tissues are sent for history-pathological examination to identify conditions such as testicular atrophy,orchitis, Sertoli cell only syndrome, hypospermatogenesis, maturation arrest or tubular hyalinization.

TESE  might be superior to TESA at obtaining sperm  in terms of the quantity and subsequent motility of the sperm found. Thus , TESE provides a better chance of cryopreservation of sperm obtained by TESE rather than TESA. such  cryopreserved sperm can be used in subsequent cycles if needed rather than the patient having to go through another TESE or TESA procedure. The sperm obtained through TESE or TESA can be used for ICSI but not IUI as the number of sperm that can be obtained through these will not be sufficient for performing an IUI.

The sperm recovery rate by these procedures is < 50%.

Other techniques are PESA, MESA, and MICRODISSECTION TESE

PESA (percutaneous epididymal sperm aspiration)- is where the sperm are recovered by aspiration from the epididymal  part of the male reproductive tract situated above the testes. The fluid aspirated from the epididymis is evaluated for the presense of sperm. If motile sperm are not seen the procedure is repeated at a slightly different location on the epididymal head (in obstructive azoospermia, better sperm are obtained from the proximal epididymis rather than the distal body or tail). Since this is a blind procedure sometimes several attempts are required before good quality sperm are found.

Advantages

The procedure is simple, quick, avoids open surgery and can be repeated.

Disadvantages

Since the epididymis is not visualized, the location of puncture is guided by palpation alone and cannot be precisely controlled. As a result, occasionally the sperm-containing ductule may be missed and hence the sperm may not be required. There is also  the possibility of puncturing a blood vessel and contaminating the sample with red blood cells.

Open versus closed epididymal sperm retrieval

Since PESA can obtain enough sperm for ICSI and for cryopreservation there is no reason to subject a patient to an open surgical procedure. If PESA fails then open fine needle aspiration biopsy can be performed. Alternatively, percutaneous testicular sperm retrieval can be done to avoid an open procedure.

MESA- Microsurgical epididymal sperm aspiration

Technique

The epididymis is exposed through a scrotal incision. Under an operating microscope the epididymal tunica is incised and an epididymal ductule is mobilized. The ductule is opened and the spermatic fluid that flows out is aspirated. Once enough sperm are recovered the ductule is closed with microsutures. If no sperm are found another ductule is dissected.

Advantages

Microsurgical visualization of the epididymis allows for precise, blood-free aspiration from multiple locations. A large number of motile sperm can be recovered and cryopreserved for future cycles of ICSI. Microsurgical handling of the ductule may preserve it for future repeat aspiration, if required.

Disadvantages

This is a time-consuming and demanding procedure that needs an operating microscope and a trained andrological microsurgeon. There is no evidence that closing the ductule microsurgically improves chances of future retrieval.

Microsurgical testicular sperm extraction – MICRO-TESE

This is a technique of surgical sperm retrieval where in the  testes is exposed by making a  long incision in the tunica ( the covering layer of testes) to expose the testicular parenchymal tissue. The seminiferous tubules are gently separated and examined under a high resolution operating microscope. Fibrous tubules can be distinguished from “healthy fat” tubules that are more likely to contain sperm. Only the promising tubules are biopsied and examined for sperm. Dissection and biopsy are continued till adequate sperm are retrieved and then the tunica is sutured.

Advantages

Since only selective tubules are biopsied, less tissue needs to be removed resulting in less testicular damage. A large area of testicular tissue can be visually  examined,evaluated and biopsied, improving the chances of finding sperm in cases with focal spermatogenesis, especially in men with Sertoli cell syndrome only and high follicle-stimulating hormone (FSH). Chances of retrieval of sperm by microdissection TESE is nearly 56% in those men where no sperm had been found in previous one to two biopsies, and in 23% of men with no sperm in previous three to four conventional biopsies.

Disadvantages

Though only a small amount of tissue is removed, the large tunical incision and the dissection of the testicular tissue can cause devascularization and fibrosis of the testis.