ALTERNATIVES AVAILABLE FOR SPERM EXTRACTION

Edward D. Kim, M.D., and Larry I. Lipshultz, M.D.

(From RESOLVE of Houston Quarterly Newsletter, Vol. 3, No. 3, July 1996.)

The ability of the urologist to address problems of severe male factor infertility has been revolutionized with the introduction of intracytoplasmic sperm injection (ICSI), a micromanipulative technique in which a single sperm is injected into an oocyte retrieved through an in vitro fertilization (IVF) cycle. Now, men previously considered untreatable and incapable of fathering their own genetic offspring are potentially able to initiate a pregnancy with ICSI. Although the first success using this technique was reported as recently as 1992, ICSI is now being performed by most major IVF centers in the United States.

PREGNANCIES RESULTING FROM EXTRACTED SPERM

The initial ICSI experiences used fresh ejaculates with severely decreased sperm densities and/or motilities. Successes using this source led to investigations employing sperm extracted from the epididymis and the testis in azoospermic (no sperm in the ejaculate) men with vasal and epididymal obstruction.

In these obstructed conditions, typically as a result of a previous vasectomy, acquired inflammation, or congenital absence of the vas deferens, sperm are abundant within the testis and epididymis because of preserved sperm production. In contrast, azoospermic men with intrinsic testicular damage or testicular failure may have sperm found within the testis, but in severely diminished numbers.

Although the best ICSI results have been with fresh ejaculates, similar pregnancy rates can be achieved using epididymal-extracted sperm. Even sperm harvested directly from the testis are capable of initiating fertilization and pregnancy, although with lower rates in comparison with epididymal and ejaculated sources. Recent reports have also demonstrated that cryopreserved (frozen) sperm produce equivalent fertilization rates compared to fresh ejaculates.

With the success of ICSI using epididymal and testicular-derived sperm in men with no sperm in the ejaculate, the question of the optimal sperm retrieval technique has been raised. The presently practiced techniques of sperm extraction include:

(1) Percutaneous methods avoiding a skin incision.

(2) "Open" methods utilizing a surgical incision.

As will become evident, each method has distinct advantages and disadvantages.

PERCUTANEOUS

Epididymal. Percutaneous epididymal sperm aspiration (PESA) involves the aspiration of sperm from the epididymis using a small (21-23 gauge butterfly) needle. Multiple passes of the needle are made until sufficient sperm are obtained. No skin incision is required, and the procedure has been performed using intravenous sedation. Researchers have reported obtaining sperm suitable for ICSI in most patients with obstruction.

In men with vaso-epididymal obstruction, we clearly prefer microepididymal sperm aspiration (MESA) to percutaneous sperm aspiration (PESA) as an epididymal sperm retrieval technique because of the 1) need for a single procedure for harvesting, 2) the diminished risk of epididymal tubular damage, and 3) ability to perform a concomitant reconstructive vaso-epididymal procedure. The increased cost of MESA and the relatively high sperm recovery rates do, however, make PESA a secondary alternative for select patients.

The results of microepididymal sperm aspiration (MESA) for obstructive azoospermia have been compared using ICSI and conventional IVF.²⁰ Because of significantly higher rates of ICSI fertilization, clinical pregnancy, and ongong pregnancy/delivery rates, ICSI has been recommended as the treatment of choice for men with obstructive azoospermia requiring MESA.^23,25,30

The cryopreservation of sperm in azoospermic men undergoing MESA is mandatory given the success of using thawed spermatozoa.⁶ Sperm cryopreservation should also be strongly encouraged at the time of procedures such as vasectomy reversal if motile sperm are present. Devroey and associates reported on seven patients who had not become pregnant after MESA and the first cycle of ICSI.⁶ A second cycle of ICSI using cryopreserved sperm resulted in one twin delivery and two ongoing singleton pregnancies. The fertilization rates between frozen and fresh sperm were comparable, but only slightly lower in the cryopreserved group (57% vs. 45%). Although the mean sperm concentration decreased from 12.3 million/ml when fresh to 1.9 million/ml after thawing, clearly enough sperm were present for ICSI.

Witt confirmed the Belgian experience with cryopreserved sperm by studying five couples after an initial cycle of failed MESA and ICSI.³⁴ With cryopreserved sperm for the second cycle, 44% of the oocytes had normal fertilization, and 2 pregnancies were established. It has been speculated that the success using cryopreserved sperm is a function of selecting out "only the best sperm." The return of motility in cryopreserved testicular spermatozoa with initial lack of spontaneous activity has also been described.²

Testicular. Percutaneous testicular sperm aspiration has been described using a small (20 gauge) needle and an aspiration cytology apparatus in men with obstruction and testicular failure. Using intravenous sedation in the office, sperm suitable for ICSI were obtained in most men with obstruction and in 50% of the men with testicular failure. A similar technique has been reported in which researchers were able to recover sperm suitable for ICSI in approximately two-thirds of men. This procedure has been termed TESA, for testicular sperm aspiration.

OPEN

Epididymal. Microepididymal sperm aspiration (MESA) has perhaps been the procedure most commonly performed in men with vasal obstruction. A scrotal skin incision is made, and the testis and epididymis are exposed. Using an operating microscope, a single epididymal tubule is opened and sperm aspirated. This procedure may be performed with a general anesthetic, or a local anesthetic with intravenous sedation.

Testicular. The performance of an open testis biopsy for extraction of sperm may be performed with either a local or general anesthetic, in the office or in the operating room. A small skin incision is utilized to expose the testis. The biopsy specimen is obtained under direct vision and may be immediately assessed for sperm using a touch preparation cytology or wet-mount examination.

PROS AND CONS

Epididymal. In men with an underlying vasal obstruction, the epididymis is the first choice for obtaining sperm due to more advanced sperm maturation and higher pregnancy rates.

PESA has the main benefits of being successful in most of the cases, while avoiding a skin incision. Costs are lower because an operating microscope, the skills of a microsurgeon, and the possibility of a general anesthetic are not necessary or likely. The most significant drawback is the ìblindî nature of the procedure, often requiring multiple, potentially damaging needle insertions. The delicate, coiled anatomy of the epididymal tubules are easily damaged with such maneuvers. While PESA may be successful for oneís first ICSI cycle, future cycles will require repeated procedures and the increased likelihood of progressive epididymal damage.

MESA has been our procedure of choice because of the ability to retrieve large numbers of sperm that may be cryopreserved (frozen) and used in future cycles. Thus, the need for future procedures is eliminated and the amount of epididymal damage quite limited. Many men may be candidates for a reconstructive epididymovasostomy (connection of the vas and epididymis, thereby bypassing a blockage) at the same time of sperm harvest, thus increasing the chances of having sperm appear in the ejaculate. Recovery time from this operative procedure is only a few days, and complications, such as infection or excessive bleeding, are rare.

Testicular. When sperm cannot be retrieved from the epididymis, the testis is often a successful alternative. Sperm may be retrieved from the testis in cases of both obstruction and failure of adequate sperm production, but significant differences exist in the two etiologies in the ability to obtain sperm.

The only condition in which percutaneous retrieval is appropriate is in the obstructed testis. In this situation, large numbers of sperm are present for retrieval, and the chances of successful recovery are high. Numerous needle passes may, however, still be required, increasing the chances of injury to the testicular blood supply and resultant testicular damage.

The open testis biopsy is appropriate for both obstruction and testis failure. A much larger biopsy is typically required for testis failure, since fewer sperm are being produced. In addition to a larger number of recovered sperm, the open technique can be performed through a tiny 5-10 mm skin incision, often with less discomfort than MESA.

CONCLUSIONS

In men with vasoepididymal obstruction, we clearly prefer MESA to PESA as an epididymal sperm retrieval technique because of:

(1) The need for a single procedure for harvesting.

(2) The diminished risk of epididymal tubular damage.

(3) The ability to perform a concomitant reconstructive vasoepididymal procedure.

The increased cost of MESA and the relatively high sperm recovery rates do, however, make PESA a secondary alternative for select patients.

When sperm cannot be retrieved from the epididymis because of severe scarring or testicular failure, we prefer the open biopsy technique because of:

(1) The larger amount of tissue and sperm which can be retrieved.

(2) The minimally invasive nature of the open technique.

Repeated needle bypasses through the testicular parenchyma places the testis at increased risk for vascular damage. While the open biopsy technique is mandatory for ICSI in patients with testicular failure, it may be considered as a second