Microsurgical Testicular Sperm Extraction: Technical Considerations

Fig. 7.1

Schematic illustration of testicular microdissection technique, demonstrating initial incision with wide exposure of seminiferous tubules, digital pressure exerted on the tunica albuginea to evert tissue, allowing the ability to dissect deep within testicular parenchyma

Microdissection TESE

In order for all areas of potential sperm production to be identified, microdissection must allow examination of all seminiferous tubules within the testis. Seminiferous tubules are highly convoluted and exist within very fine septae, with centrifugal vessels running in parallel to the tubules and septae (Fig. 7.1.) Dissection between the tubules allows access to deeper sections of the seminiferous tubules, down to the level of the tunica albuginea. It is critical to maintain blood supply along the tubules during the dissection and to avoid separation of tubules from the tunica albuginea. The space between the tubules and tunica has an extensive array of subtunical vessels that are prone to excessive bleeding and very difficult to control if this space is entered during microdissection. The higher the power of magnification used during microdissection, the easier it is to determine which of the tubules is larger/more normal. The sperm retrieval procedure can be tedious, especially in larger testes, and may take several hours to adequately and safely examine all areas of the testis, even for microsurgeons experienced in this technique.

Critical Points of Surgical Technique

Wide incision along an equatorial plane allows complete exposure of seminiferous tubules.
Exposure of the initially exposed tubules is inadequate to find many sites of sperm production.
Dissection parallel to the centrifugal vessels allows dissection deep within testicular parenchyma.
Gentle pressure across the tubules being dissected is important to allow blunt separation of tissue.
Pressure under the tunica albuginea to evert the testicular tissue for microdissection.
A vertical incision in the tunica albuginea is an alternative, but carries a greater risk of injury to testicular vessels and does not allow organized dissection of seminiferous tubules.

The original description of microdissection TESE was published in 1999. In the study, Schlegel reported that historical rate of sperm retrieval using multibiopsy TESE was 45%. Sperm retrieval increased to 63% with application of micro-TESE. In a controlled study, where testicular sperm extraction was performed on one side with TESE on the other, sperm retrieval using TESE with multiple biopsies alone would miss sperm in nearly a third of the men who could have sperm found by micro-TESE. Another study by Amer et al. in 2000 documented higher sperm retrieval rates with micro-TESE (47%) compared to standard, multibiopsy TESE (30%). In addition, the rate of acute and chronic complications including testicular atrophy and devascularization was markedly lower for patients who had micro-TESE [12]. A further study by Okada et al. documented improved sperm retrieval rates using microdissection TESE compared to standard TESE, with differences most pronounced in those patients who had predominant Sertoli cell-only pattern (where the difference in size of seminiferous tubules is more dramatic.). In an update of results of this technique, with experience in 460 patients who underwent microdissection for NOA, sperm retrieval was accomplished with micro-TESE in 62% of cases whereas the sperm retrieval rate with standard multibiopsy TESE was only 32% [13]. The safety of micro-TESE was also demonstrated in a retrospective review by Ramasamy et al. from Cornell. In this study, effects of testicular sperm extraction using a multibiopsy technique or microdissection were compared by following patients with serial scrotal ultrasound as well as serial testosterone levels after TESE. Patients had earlier and more complete recovery of testosterone production after microdissection TESE, with return of serum testosterone to 95% of baseline after 18 months, whereas patients after standard TESE had recovery only to 85% of baseline levels. Similarly, acute and chronic changes as detected on scrotal ultrasound were less common in patients who had microdissection TESE. The lower complication rate after microdissection TESE is likely related to the ease and complete achievement of hemostasis during this procedure.

Sperm Processing

If sperm production is present within testicular parenchyma for men with NOA, then the sperm are within the seminiferous tubules. The efficiency of finding sperm is enhanced by aggressively mincing the testicular tissue to allow sperm to be released from the tubules and identified. The amount of tissue that is removed during microdissection TESE is typically much less obtained from multibiopsy TESE procedures (50-fold less tissue excised). To assure that the testicular tissue suspension has been adequately disrupted and sperm can be most easily identified on wet-prep in the operating room, the testicular suspension is passed sequentially through a 24-guage angiocatheter to confirm adequate suspension. This approach can increase sperm yield up to 300-fold [14]. Each specimen with enlarged seminiferous tubules should be sequentially examined for the presence of sperm in the operating room, since the procedure can be terminated once sperm are found. Since sperm do not survive freeze–thaw very efficiently, intentional removal of additional testicular tissue may waste the sperm production that is present and create additional scar tissue within the testis, potentially compromising future attempts at fertility treatment.

Overall Results with micro-TESE at Cornell

Encouraging experience has been obtained at Weill Cornell with TESE-ICSI in the past 1,357 attempted treatment cycles for couples in whom the man had NOA. The mean age of patients entering treatment was 36.1 years for men and 31.8 years for women. In men, the initial mean serum FSH level was 21.6 IU/L (normal 1–8 IU/L), and average testis volume 9.6 cm³. During the past 1,357 attempted TESE-ICSI cycles, sperm were retrieved for injection in 763 cycles (56.1% retrieval rate). For those cycles in which sperm were retrieved, the fertilization rate per injected oocyte was 51.1% (4,272/8,365), and embryo transfer occurred in 92% of cycles. Clinical pregnancies (fetal heartbeat on ultrasound) were established in 49.1% (375/763) of evaluable cycles and live deliveries occurred in 40% of cycles with retrieved sperm for which sufficient time had passed for completed gestation. Over 320 children have been born from our center. Twin deliveries occurred in 11% of cases, triplets in <1%, and singleton deliveries for the remainder.

No etiology of azoospermia provided an absolute predictor for the presence or absence of sperm within the testes, except for complete deletions of the AZFa and AZFb regions of the Y chromosome, that was associated with a 0% retrieval rate.

Micro-TESE After Failed Standard TESE

The superiority of microdissection TESE as an approach for sperm retrieval in NOA is also suggested by a recent publication by Ramasamy et al. where patients who had previous failed biopsy or TESE procedures subsequently underwent microdissection TESE [15]. In this report, patients who had no prior biopsy had a 52% rate of sperm retrieval with micro-TESE. Patients who had one or two biopsies per testis for an attempt at testicular sperm extraction had a sperm retrieval rate of 50% as well. If three or four or more biopsies per testis were done in an attempt to extract sperm, the subsequent sperm retrieval rate with microdissection TESE was 22%. These data strongly suggest that blind, random biopsies of the testis will commonly miss areas of sperm production. Indeed, one or two biopsies per testis provide inadequate evaluation of testicular parenchyma and provides information that is little better than proceeding with micro-TESE with no prior biopsies whatsoever. Even if TESE is done with three or more biopsies per testis, the chance of sperm identification using the micro-TESE approach was still 22%. So, failure of sperm retrieval with standard TESE still leaves open the opportunity of sperm retrieval with micro-TESE.

Predictors of micro-TESE Success

FSH

In another study performed at Cornell, the relationship between serum FSH and sperm retrieval results were analyzed for men who underwent microdissection TESE. Patients who had serum FSH of 15–30, 30–45, or greater than 45 all had similar sperm retrieval results (average of 63%). Even men with FSH levels over 90 IU/L can have sperm retrieved with micro-TESE. These observations suggest that small areas of spermatogenesis, inadequate to affect serum FSH (or testicular volume) may be present and will commonly be found using microdissection TESE [16]. Indeed, the only patients with NOA who had a different rate of sperm retrieval was for men with an FSH <15, where sperm retrieval rate is 51%. This subgroup of patients has an increased risk of uniform maturation arrest, where genetic abnormalities are common and the chance of sperm retrieval is adversely affected [17]. Previous studies have suggested that serum FSH is a good predictor of the chance of sperm retrieval. These studies were done predominantly with single or multiple random biopsies of the testis for sperm retrieval. These observations suggest that random biopsies of the testis may identify the predominant pattern of sperm production but do not necessarily identify the best area of sperm production within the testis. The observation from this retrospective review that microdissection TESE is superior in finding sperm for men with the most severe defects in sperm production further supports micro-TESE as the optimal approach for sperm retrieval in men with NOA.

Klinefelter Syndrome

One paradigm for the most severe cases of NOA is those men with Klinefelter syndrome. These patients typically have a testicular volume of 2.5 cm³’s with markedly elevated FSH. In an initial report, the chance of sperm retrieval for men with Klinefelter syndrome who underwent microdissection TESE was 71%. These excellent results were obtained despite the very small testicular volume present in these patients, likely because the micro-TESE technique is effective at finding small, limited areas of sperm production within the testis.

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