Sperm Mapping, Also Known As Testicular Mapping or FNA Mapping
Alternative To Testis Biopsy (Microdissection)
Sperm Mapping is a technology invented by fertility Dr. Turek to “map” out the location of sperm in the testis. The technique is designed to benefit severely infertile men. It is a minimally-invasive, non-surgical procedure performed under local anesthesia in one of our clinics.
With Sperm Mapping, Dr. Turek can determine if a man with azoospermia (no sperm in the ejaculate) is a candidate for sperm retrieval to have children. Sperm Mapping also helps to minimize invasive testis sperm retrievals and reduces the potential damage to the testis from these procedures.
To learn more about Sperm Mapping, please watch the video below or read the following topics. If you are ready to schedule a consultation for Sperm Mapping, please request a consultation here.
Sperm Mapping for Azoospermia
For the last 50 years, the evaluation of men with azoospermia has involved determining if sperm production is normal or not through a surgical procedure called a testis biopsy. Sperm Mapping is a non-surgical alternative to the testis biopsy and is done with a technique called fine needle aspiration (FNA). FNA has been used to examine human tissue for over 100 years, and is very popular now for breast cancer diagnosis. Testis FNA is similar to a testis biopsy in terms of the information gained about sperm production, but much less invasive and less painful than a biopsy. Because of this, it can be used to sample many places throughout the testis and is therefore more informative than a testis biopsy. Recently, testis FNA has become popular in the field of male infertility because:
- It is a minimally invasive method that offers a wealth of information about a man’s sperm production.
- It is clear that testis biopsy patterns as currently reported do not correlate well to either a) the reason for infertility, or b) to the ability to find sperm in the testis.
- Assisted reproduction (IVF) has advanced such that sperm from the testis are routinely used for pregnancy, further fueling the development of this novel technique as a way for azoospermic men to become biological fathers.
Sperm Mapping Procedure
Sperm Mapping is a small procedure performed in the office on a come-and-go basis. It takes about 45-50 minutes to do (Figure 1) under local anesthesia; oral sedatives can be taken if the patient desires. First, the scrotum is sterilely prepped and the area numbed with local anesthesia. Each testis is approached separately and anywhere from 11-18 FNA samples are taken from each side (Figure 1) through the scrotal skin. There are no cuts or incisions in the scrotum or testis. Pressure is applied for several minutes and the patient is advised to rest for one day after the procedure (post-procedure instructions can be found here). Patients are prescribed pain pills and take an average of two pain pills after the procedure. They can return to work and normal activity within 24 hours. Side effects and complications are few. In Dr. Turek’s experience with over 1,200 cases, there is a < 0.5% chance of infection, bleeding or chronic pain.
Sperm Mapping for the Health Care Professional
An example of how the sperm mapping procedure is setup is shown in Figure 2.
Each FNA sample is collected from a specific location in the testis according to a standard template (Figure 1). After sampling, the tissue within the needle is placed on a microscope slide and smeared using standard hematologic technique to spread out the cells over the whole slide (Figure 3). After smearing, the sample slide is placed in alcohol fixative. It is then stained with a standard PAP (Papanicolou) stain and reviewed in detail by an experienced team of cytologists who study the slides under high power microscopy to find sperm with tails.
Only a very small amount of testis tissue is needed from each mapped site for the Sperm Mapping technique (Figure 3). This is quite different from the much larger samples of testis tissue obtained by open surgical biopsy.
After staining, the slides are reviewed for several hours by a team of trained cytologists for the presence or absence of sperm (Figure 4). Importantly, these sperm are stained at this point and cannot be used clinically for pregnancies.
In addition to finding sperm, many other testis cell types can be readily identified on each mapped slide, including supporting cells such as Sertoli cells, Leydig cells and myoid cells, and various cells of the germ cell sequence that lead up to mature sperm including spermatogonia, primary spermatocytes, spermatids (round and elongating) and mature sperm with tails (Figure 5).
Sperm Mapping vs. Testis Biopsy
In men with nonobstructive azoospermia in which there is no sperm in the ejaculate due to a sperm production problem (and not a blockage), there may still be usable sperm within the testis. However, Dr. Turek’s infertility research has shown that in such instances the sperm may be located in “pockets” and may not be found everywhere (Figure 6). That is, some places in the testis may have sperm and others may not, like apples on the branches of a tree. This “patchy” or “focal” nature of sperm production makes finding testis sperm difficult in many cases. Due to this fact, a single testis biopsy, or even multiple testis biopsies, can “miss” finding sperm in men with nonobstructive azooospermia. Potentially, many more testis biopsies than are currently taken may be needed to find sperm, but adding more biopsies can jeopardize the health and survival of the testis. Another issue with finding sperm in biopsies is that many laboratories that receive the fresh biopsy tissue to look for sperm are not looking at the sample with as much effort as is needed to find sperm. And even if the laboratory is very experienced, they do not have the benefit of a PAP stain (used with Mapping) that precisely and accurately distinguishes all of the germ cell types in the testis sample.
Regarding the standard testis biopsy that is also often performed in nonobstructive azoospermic men, Dr. Turek has also published that testis biopsies that are sent to a pathologist for review may not be read as accurately for the presence of sperm as one might want. Unlike a biopsy, Sperm Mapping allows for precise, systematic examination of many areas of the testis and can allow men with even the severest forms of infertility, including cancer survivors to become biological fathers.
Your Sperm Mapping Results
The Location and Quantity of Sperm
Think of Sperm Mapping as “testis GPS” or “testicular cartography” as some patients have put it. If you were planning a long drive across half of the country, headed to a specific place, wouldn’t it be more efficient and waste less gas if you had help from a map? Sperm Mapping informs you whether or not there is sperm in the testis, where it is located and how much is present. As Dr. Turek has published, this information is then used to “guide” or “direct” sperm retrieval for IVF-ICSI performed at a later date. In this way, sperm retrieval is tailored to the patient, and is potentially less damaging to the testis as described further below.
In his experience, sperm retrieval guided by prior Sperm Mapping found sufficient sperm for all eggs at IVF-ICSI in 95% of cases. In addition, prior Sperm Mapping helped to minimize the number of biopsies and volume of testicular tissue taken to acquire sufficient sperm. So, Sperm Mapping really is a form of “testis GPS.”
There is another matter to consider here. Remember that the testis makes the male hormone testosterone in addition to sperm. Sperm retrieval procedures that “spare” the testis are particularly important in men with small or solitary testes. That is because if too much testis tissue is removed during the sperm retrieval, some men can have too little testis tissue left to maintain normal healthy testosterone levels. And this could result in the need for lifelong testosterone replacement. Think of having to drive across the country to that special place without a map and with only a limited amount of gas. If you take too many wrong turns, you might not make it to the destination at all because you simply run out of gas. So, Sperm Mapping can help conserve testis tissue, since knowing the location of sperm in the testis in advance of sperm retrieval (i.e. having a “map”) allows one to minimize the invasiveness of the sperm retrieval procedure.
The Testis Biopsy PatternSperm Mapping can also be used to “read” the biopsy histology without the need for a formal biopsy. In fact, Dr. Turek has published on the accuracy of Sperm Mapping to read biopsy histology. He developed a working classification system for doing this based on pattern recognition. The patterns represent histological diagnoses but are based on relative numbers of 3 easily identified germ cell types found on Sperm Mapping: primary spermatocytes, spermatids, and spermatozoa (Figure 5, 7). The relative number of various germ cells and Sertoli cells are quantified and a standard ratio of cell types for comparison to Sertoli cell numbers is created. An example of how this system is used to define Sertoli cell-only, and early maturation arrest pathology by Mapping is shown in Figure 7. In a series of 87 patients with paired FNA maps and biopsy, this classification system was observed to be reproducible and accurate (94%) suggesting that Sperm Mapping can replace testis biopsy histology. Of note, although Sperm Mapping has been used to noninvasively identify testis tumors the testis biopsy is still the “gold standard” for these diagnoses.
Next Steps after Sperm Mapping
Overall, sperm retrieval for IVF-ICSI with infertility due to nonobstructive azoospermia is successful 40-60% of the time without the guidance of Sperm Mapping. This means that many couples have to settle for egg freezing, IVF cycle cancellation or using donor sperm at the time of IVF instead of using their partner’s sperm. With the addition of Sperm Mapping, the rate of successful sperm retrieval is increased substantially, as shown in Figure 8. In addition, based on Sperm Mapping findings and the knowledge of sperm location in advance, sperm retrieval procedures can be tailored for each patient and proceed from the least invasive to the most invasive methods. From a review of 159 of Dr. Turek’s cases of nonobstructive azoospermia, 44% of Mapped cases required sperm retrieval by needle aspiration (TESA, least invasive), 33% required open, directed surgical biopsies (TESE, more invasive) and only 23% needed microdissection TESE (most invasive) for successful sperm retrieval (Figure 8). In other centers, all of these men might have undergone the most invasive sperm retrieval procedure, microdissection TESE, when it could have been avoided.
In addition, the majority (78%) of Mapped cases require sperm retrieval from only one testis and not both to find sufficient sperm for IVF-ICSI which reduces the risk of lowering testosterone after sperm retrieval even more. Lastly, among men who underwent a second sperm retrieval procedure guided by prior Sperm Mapping, sperm was successfully retrieved in 91% of attempts. This suggests that knowledge of sperm location with Sperm Mapping can simplify and streamline sperm retrieval procedures in difficult cases of nonobstructive azoospermia and can also be relied upon to guide subsequent sperm retrievals.
Advantages of Sperm Mapping for Azoospermia
In Dr. Turek’s first published research with Sperm Mapping, he designed a head-to-head comparison of the Sperm Mapping technique and testis biopsy procedure in finding sperm in azoospermic men. He undertook this study because Sperm Mapping and testis biopsies are evaluated differently: Sperm Mapping is evaluated by cytology and a testis biopsy by histology. Because only with cytology can one see actual sperm tails, Dr. Turek thought that in a head-to-head comparison, cytology would be more accurate for identifying sperm. In this study, infertile men underwent both testis biopsies and site-matched Sperm Mapping, and Mapping found sperm more often than a biopsy. That is, more men had sperm found by Mapping than on biopsy from the same location. Since it was far less invasive than a biopsy but more informative about sperm, this paved the way for Dr. Turek to push the technology further and develop his sophisticated Sperm Mapping technique.After this study, Dr. Turek has continued to examine the power of Sperm Mapping and continues to improve the technique. He has increased the number of mapped sites in each testis from 6 to 8 to 11 and now can safely sample up to 18 sites in each testis. The ability to detect sperm has grown as the intensity of sampling has increased, as shown in Figure 9.
New Techniques Beyond Sperm Mapping
Never content to leave well enough alone, Dr. Turek is developing and has recently published on a method of mapping sperm in the testis that is entirely noninvasive and nonsurgical in nature. It is termed metabolic mapping. Using metabolomic technology and MRI scanning, men will undergo a simple MRI scan that incorporates perfectly safe spectroscopy (e.g. PET scans) to obtain important metabolic information about the cellular activity within the testis. Since the vast majority of cellular activity in the testis is associated with the production of sperm, this may be able to be measured and a chemical “signature” for sperm identified. Not only that, it is likely that the testis can be imaged and chemically “sampled” for sperm in as many as 100-200 areas instead of the 15-18 areas currently examined by Sperm Mapping. Dr. Turek’s published preliminary data on this technology has shown that metabolic sampling of testis biopsies from infertile men can already read testis biopsy patterns quite accurately. Dr. Turek is counting on this technology to better identify sperm in azoospermic men than is currently possible with much more invasive techniques and truly believes that men would prefer to be scanned than biopsied to learn whether they can be biological fathers.