The Options for Sperm Retrieval
Choosing the Best Technique for You
By: Michael A. Witt, M. D.
Reproductive Biology Associates
Intracytoplasmic sperm injection has opened a whole new world in the area of sperm retrieval. By reducing the critical number of sperm needed to establish fertilization to a single sperm, urologists can now be much more aggressive in their search for sperm in any reservoir. The demand for usable sperm by our patients, reproductive endocrinologists and embryologists has created a need for urologists' skill in sperm retrieval that did not exist 10 years ago. As experience with sperm retrieval has grown, so has its sophistication and application. We can now treat many more patients than formerly, and with greater success. Experience has also answered many questions about sperm retrieval, but it has also created many unanswered questions.
The purpose of this article is to address some of the unanswerable and answerable questions. The discussion surrounding these questions can be broadly categorized into 7 areas:
- What are the various sperm retrieval techniques?
- When should each technique be employed?
- How is each technique performed?
- How often can these procedures be performed?
- How should specimens be processed, and by whom?
- When, can and how should specimens be cryopreserved?
- What are the results with each type of specimen?
The various techniques for sperm retrieval are defined by the type of surgical approach and reservoir. The surgical approaches are either an open or a percutaneous procedure. Open procedures involve direct visual inspection of the reservoir during which excisional or aspiration techniques are employed. Percutaneous techniques utilize aspiration techniques combined with palpation or ultrasonographic imaging. The reservoirs available for sperm retrieval are seminal vesicle, vas deferens, alloplastic, epididymis and testicle.
Table I - Techniques for Sperm Retrieval
a. Seminal vesicle
b. Vas deferens
The type of procedure performed depends upon reservoir availability, indications for the procedure, the cost of the procedure, the type assisted reproductive technique couple will utilize, the experience of laboratory personnel handling the specimen, the importance to the patient of cryopreservation, and the potential for success.
The type of reservoirs available will be largely dependent upon the indication for the procedure and where sperm can be found. Identical diagnoses do not produce the same available sperm reservoirs. This is why careful evaluation by a skilled urologist is necessary. The fact that the patient is azoospermic and has a testicle does not necessarily mean that the testicle is the reservoir to utilize. For structural or functional obstructive azoospermia, the best reservoir may be the epididymis. The epididymis will provide the cleanest specimen with the greatest numbers of motile sperm. For these reasons the epididymal specimen will be relatively easy to handle by the laboratory for use with any of the assisted reproductive techniques and/or for cryopreservation. The epididymis can be accessed with an open or percutaneous technique. I prefer the percutaneous technique because it reliably provides the best specimen with the fewest complications and the lowest cost. If the epididymis is not available, then the testicle becomes the next choice. The testicle can be accessed either percutaneously or with an open excisional biopsy. I prefer the percutaneous technique for obstructive azoospermia because it is equally reliable when compared to the open technique, but provides a cleaner specimen for the laboratory with less expense and invasion for the patient.
If the seminal vesicle is accessible because it is obstructed, then the patient is better served by correcting the ejaculatory duct obstruction, then aspirating the seminal vesicle. The vas deferens can be used in men with functional obstructive azoospermia. This is most frequently encountered in psychogenic, traumatic or neurologic anejaculation.
For non-obstructive azoospermia, non-obstructive sero-oligospermia or non-obstructive necrospermia, the best reservoir is the testicle. The testicle can be accessed in an open or percutaneous manner, but the best method is the open excisional approach using microdissection. This provides the greatest chance of retrieving sperm with the least amount of tissue removed.
The principal qualification for the surgeon performing sperm retrieval is the ability to perform all of the various techniques. This is because the goal of these procedures is to obtain sperm and not to reconstruct or extirpate. It is not uncommon to have to modify the original procedure because you do not find sperm where you originally thought they would be. The secondary requirement for performing these procedures is the necessity of having a skilled andrology laboratory that can inspect and process these specimens as they are procured. It is the laboratory that will inform you whether sperm have been obtained and when they have been obtained, if they are usable for the intended assisted reproductive technique. The laboratory will also handle any processing or cryopreservation of the specimen. It is important to remember that the criterion for successful procedure is the placement of sperm in the reproductive tract or oocyte. The fact that sperm have been found and procured by the urologist does not necessarily mean the retrieval procedure is complete until the laboratory reports that a usable specimen has been obtained.
The open surgical techniques involve exposing the vas deferens, epididymis or testicle and retrieving sperm from these various sites of the dissection. For optimal results, optimal magnification is recommended and, when possible, an operating microscope. The vas deferens is handled in the same way as an open vasotomy. It is optimal to irrigate the testicular and abdominal end of the vasotomy in order to flush sperm out of the luminal compartment. The effluent is collected, inspected and processed. The epididymis is approached by identifying visually tubules with the potential of good sperm quality. The ideal tubule is one that is dilated and possesses a pearl gray appearance as opposed to a yellow or white appearance. The tubule is opened or punctured and the fluids extracted and inspected. As many tubules as necessary are entered. Meticulous hemostasis is critical for securing an uncontaminated specimen. I recommend closing all tubules as well as the parietal tunica vaginalis in order to increase the likelihood of successful repeat aspirations.
For open retrieval of sperm from the testicle, I use the microdissection technique. In this procedure, the testicle is opened so all of its contents can be inspected under the microscope. The microdissection technique increases the probability of finding sperm and decreases the amount of tissue that needs to be extracted. Multiple biopsies are taken until sperm can be isolated, or until no more of the testicle can be sampled. Once tissue is obtained, it is given to the laboratory personnel for inspection and processing. This technique does require an operating room and IV sedation because the testicle is vigorously manipulated, and the procedure can take upwards of 2 hours.
The percutaneous technique involves placing a fine needle into the intended reservoir and aspirating its contents in hopes of obtaining sperm. These procedures have the advantage of being less expensive and less invasive, but the disadvantage of being less reliable and with a lower yield. The seminal vesicle reservoir is punctured under ultrasonographic guidance with an 18 g. needle and aspirated. This technique was developed as a diagnostic technique for identifying complete or partial ejaculatory duct obstruction. This technique is seldom used. The epididymal reservoir can be entered percutaneously after being localized and isolated with palpation. A 21-23 g. needle is used with aspiration. Multiple passes are required and slow placement is critical in order to successfully withdraw fluid. This procedure is performed in the office, and has the potential of yielding the greatest number of motile sperm.
Percutaneous testicular aspiration, or non-surgical sperm aspiration, involves entering the testicle with a needle and making multiple passes with a 2-3" 21 g. needle under high negative pressures. This procedure can be performed in the office using only local anesthesia. Typically, fragments of seminiferous tubules become trapped in the tip of the needle and drawn out to the skin. The sperm are found within the seminiferous tubules. This technique is performed for men with obstructive azoospermia.
Multiple procedures can be performed in any reservoir as long as previous retrieval did not completely eliminate the compartment from which the sperm were obtained. Percutaneous retrieval of sperm from the testicle in the case of obstructive azoospermia has almost unlimited application. Repeat percutaneous aspiration of sperm from the epididymis is fraught with more difficulty because the uncontrolled access to the tubules at the first aspiration obliterates most of the remaining tubules. This is in contrast to an open epididymal aspiration in which controlled access and anatomic restoration of the tubule and tunica vaginalis allows for repeat procedures. Open testicular sperm retrieval can be readily repeated. It is recommended to wait at least 6 months between attempts in order to allow for better delineation of viable and non-viable segments of the seminiferous tubules, and for full recovery of the terminal epithelium from the initial insult period. In general repeat open retrievals of the epididymis and testicle are more difficult than the initial attempt due to the inevitable formation of scar tissue.
I cannot stress how important the laboratory function is in guaranteeing successful retrieval and outcome. The laboratory is solely responsible for the processing and manipulation of the specimen. It is important the laboratory personnel be motivated in handling these specimens because it can be a tedious and painstaking process. It is also essential for good communication to be established between the urologist and the laboratory. Feedback is crucial for modifying procedures intraoperatively, planning for future retrievals and reviewing past successes and failures in order to improve outcomes. Limitations to the laboratory also need to be defined, being that not all described procedures can be performed by all laboratories.
The cryopreservation of vasal, epididymal and testicular specimens has provided patients with the capacity to perform multiple cycles of assisted reproduction from one retrieval procedure. This has significantly reduced the total cost of establishing a pregnancy, subjected the patient to fewer invasive procedures, and allowed for greater predictability in scheduling of the initial sperm retrieval.
I have found many misconceptions exist about the cryopreservation of vasal, epididymal, and testicular specimens. It is presumptive to think that all specimens and all sperm can be successfully cryopreserved. Just as ejaculated specimens vary in their post-thaw survivability, so do retrieved specimens. This survivability rate determines the critical number of sperm needed before freezing in order to end up with a usable specimen after thawing. Even when good numbers of sperm survive upon thawing, identifying viable, non-motile sperm is still not an exact science. Until this identification process is more refined, then the fact that you can freeze specimen does not mean it is usable. This fact is particularly critical in the area of intracytoplasmic sperm injection because a single sperm is matched with a single oocyte. A general rule to follow is that the better the specimen you begin with, the greater the likelihood that a usable fraction will be obtained when the specimen is finally thawed. In addition, it is imperative to determine how well your laboratory can freeze and thaw these specimens and what are the fertilization and pregnancy rates with these cryopreserved specimens. I have found that all specimens cannot be frozen. Our laboratory makes a decision of freezing based on numbers and motility. Our laboratory has also found that pregnancy rates with poor epididymal specimens and testicular sperm in the non-obstructive patient pale in comparison to the pregnancy rates with fresh or epididymal specimens and testicular sperm. For that reason we do not routinely freeze poor epididymal or testicular specimens. I also recommend to all patients with frozen, good epididymal sperm to be prepared for retrieval procedure on the day of the wife's ovulation, in the event that the frozen specimen thaws poorly.
Results in general fresh epididymal or testicular specimens for men with obstructive azoospermia will generate fertilization rates between 50 to 70% with an associated pregnancy rate between 35 and 50% when used in combination with intracytoplasmic sperm injection. Fresh testicular specimens from men with non-obstructive azoospermia will generate fertilization rates between 40-60% with associated pregnancy rates between 35 and 55% when used in combination with intracytoplasmic sperm injection. I do not think identical epididymal sperm behave any differently than identical testicular sperm, except that from the testicular reservoir there is a higher risk of genetic abnormalities that can reduce the fertilization and pregnancy rates. Testicular sperm do present some additional challenges to the laboratory in that the numbers of sperm obtained are significantly less in the specimen that is predominantly non-motile. Another factor, which affects these success rates, is the age of the wife. As maternal age exceeds 37 years, the fertilization and pregnancy rates drop significantly.
Sperm retrieval from the genital tract has provided couples previously
considered terminally infertile a means of initiating a pregnancy in which
both partners contribute genetically to the offspring. As these techniques
have developed, it has created a bigger role for the expertise of the
urologist in performing the procedure and managing the couple. Contrary to
some predictions that intracytoplasmic sperm injection has eliminated the
need for someone with the skill to evaluate and treat the male, I think it
has accomplished just the opposite.