Robotic applications for infertility surgeries





Introduction


The concept of robots mechanically assisting humans with tasks has been a longstanding aspiration in society. Although this desire has been one of great interest in many diverse fields, in medicine this goal has been realized. The development of the da Vinci robotic system represents the most advanced robotic platform to date with real-world clinical utility. This system was initially developed for gross surgical procedures and has progressed for use in microsurgical procedures, which lends itself especially well to male fertility procedures, which have traditionally been performed with an operative microscope by reproductive urologists. In male fertility surgery, the robotic platform is particularly useful for robotic-assisted vasectomy reversal (RAVR) and robotic-assisted varicocele repair (RAVx), two of the most common microsurgical male fertility procedures. The operative microscope was initially used for surgery in 1970. This allowed for surgery on smaller anatomic structures that were considered inoperable or high risk prior to the use of the operative microscope because of the lack of precision with gross visualization. Microsurgery has been considered the standard of care for male fertility surgery, and surgical advantages may be gained with the application of the robotic platform for these microsurgical procedures.


Approximately 500,000 men undergo vasectomy for contraception in the United States annually. Of those men, 6% (30,000 men) will pursue a vasectomy reversal (VR) to reestablish fertility potential. The high number of VRs in the United States is mainly attributable to the 50% divorce rate. , VR was initially described in the 1930s, but significant improvements in patency rates were not reported until the 1970s with the use of the operative microscope for magnification to assist with the microscopic anastomosis. A varicocele is the most common diagnosis in infertile men. Varicoceles are abnormally dilated scrotal veins, with an incidence of approximately 15% in the general population, and are diagnosed in 40% of men presenting for fertility evaluations, as well as being a common etiology for scrotal pain. Varicocele repair has been shown to improve semen parameter values and pregnancy rates. Traditionally, varicocele repair has been performed microsurgically to visualize and ligate all the offending veins and preserve the gonadal arteries and lymphatics in the spermatic cord. Both VR and varicocele repair were initially attempted without any magnification tools and were performed using the naked eye, resulting in fairly poor outcomes. With the evolution of surgical magnification technology, these procedures progressed first with the use of optical loupes, then the operative microscope, and now the robotic platform. The da vinci robotic platform offers the microsurgeon improved ergonomics and less fatigue, with robotic EndoWrists allowing for movements beyond those that the hand and wrist of a human being can make. The instrumentation allows for seven degrees of freedom, scalability of microsurgical motion, and high-definition three-dimensional visualization of the microsurgical field up to 10X–15X. Operative times tend to be shorter after mastering the learning curve on the use of robotics for microsurgical male fertility surgery. The components of the da Vinci system ( Fig. 42.1 ) include the surgeon console and the bedside robotic arms for the camera and selected instrumentation.




Fig. 42.1


The components of the da Vinci robot include the surgeon console and the bedside robotic arms for the camera and selected instrumentation.


Anatomy


As with all forms of surgery, for successful and safe outcomes, a masterful knowledge of the male reproductive anatomy is crucial for VR and varicocele repair. The distal end of the cauda of the epididymis extends to form the vas deferens. The vas deferens originates from its embryologic origin, the mesonephric (Wolffian) duct. The segment of the vas deferens exiting the distal cauda of the epididymis as a tortuous hollow tube is known as the convoluted vas deferens, with a length of 2 to 3 cm. The vas deferens has a total length of 25 to 30 cm, measuring from the distal cauda of the epididymis to its termination into the ejaculatory duct. The vas deferens runs adjacent and posterior to the spermatic cord vessels. The luminal diameter of the vas deferens varies between 0.2 and 0.7 mm depending on the segment. The deferential artery, a branch off of the superior vesical artery, is the primary blood supply to the vas deferens. The venous drainage of the scrotal vas deferens is the deferential vein that drains into the pampiniform plexus. A varicocele is an abnormal dilation of the veins draining into the pampiniform plexus. The venous drainage of the pelvic vas deferens is via the pelvic venous plexus. The lymphatic drainage of the vas deferens travels to the internal and external iliac lymph nodes.


Sperm transits from the testis through the epididymis to reach the vas deferens. The epididymis is a tightly coiled tubular network, which, if straightened, would stretch 12–15 feet in length. The epididymis is composed of three regions: the caput (head), the corpus (body), and the cauda (tail). Eight to twelve ductuli efferentes from the testis make up the caput of the epididymis. The most distal segment of the cauda transitions to become the vas deferens. The caput and corpus receive epididymal arterial supply originating from branches of the testicular artery. The cauda of the epididymis receives its arterial supply from branches of the deferential artery. The vena marginalis of Haberer provides venous drainage of the cauda and corpus of the epididymis, which eventually drains into the pampiniform plexus via the vena marginalis of the testis or the cremasteric or deferential veins. The lymphatic drainage of the caput and corpus of the epididymis are via channels traveling alongside the internal spermatic vein, and they drain into the preaortic nodes. The lymphatic channels draining the cauda of the epididymis join those draining the vas deferens to the external iliac nodes.


Preoperative assessment


Vasectomy reversal patient


The preoperative evaluation of a man interested in undergoing RAVR should include an estimation of the level of spermatogenesis. A history of proven fertility prior to vasectomy is considered sufficient. A complete physical examination with focus on the genital examination should be performed prior to RAVR. Firm consistency and normal volumes of the testicles on exam are good indicators of spermatogenesis, as opposed to small, soft testes, which raise suspicion for spermatogenic dysfunction. Men who have undergone vasectomy will commonly have palpably dilated epididymides on exam. Induration of the epididymis may indicate a level of obstruction of the epididymis and may be a predictor for the need for robotic-assisted vasoepididymostomy (RAVE). When the physical exam reveals a large vasectomy gap by palpation, the patient should be counseled that a larger incision and a more extensive dissection may be required to perform the anastomosis in a tension-free manner. A palpable sperm granuloma at the testicular end of the vasectomy defect is associated with improved VR outcomes, as the granuloma is formed by sperm extravasation due to a pop-off valve-like mechanism to protect the ductal system by reducing intraepididymal pressures. A nonstandard incisional approach may be expected when an extremely long vasectomy defect is palpable on exam. As societal trends are consistent with older men desiring VR to reestablish fertility potential and younger men being diagnosed with hypogonadism, the preoperative history should include whether the man uses testosterone replacement therapy because of its adverse impact on spermatogenesis. Men on testosterone replacement therapy who are interested in pursuing VR should discontinue testosterone therapy and initiate testicular salvage medical therapy with clomiphene citrate (CC) or human chorionic gonadotropin (hCG) for at a minimum of 3 months before proceeding with RAVR.


The obstructive interval since the vasectomy plays a significant role in the level of RAVR that may be necessary, either robotic-assisted vasovasostomy (RAVV) or RAVE. Generally, longer obstructive intervals are associated with lower patency rates and make the patient a more challenging candidate for RAVR. , Experienced surgeons should still be able to offer RAVR to men with longer obstructive intervals with technical proficiency and good outcomes. In the hands of technically skilled surgeons, patency rates are high regardless of the need for RAVV or RAVE in men with obstructive intervals longer than 10 years. Nomograms have been developed to preoperatively predict which patients would require vasovasostomy (VV) versus vasoepididymostomy (VE) by assessing factors such as age, testicular volumes, the presence of a sperm granuloma, and the obstructive interval. , The data on these types of nomograms have been inconsistent, and their ability to predict which type of VR is needed preoperatively has been challenged. , Because prediction is typically not accurate based on factors such as if a VE will be required preoperatively, it is recommended that only surgeons proficiently trained and skilled in performing both VV and VE perform VRs. , The female partner of the man desiring VR should undergo a fertility evaluation to assess tubal status and ovarian reserve prior to the decision that VR is the optimal decision for that couple. ,


A semen analysis with examination of the centrifuged pellet may be performed prior to VR, although it is not a common clinical practice. Ten percent of the time, whole sperm are found in the centrifuged pellet suggesting that sperm will be found in the vas deferens intraoperatively, at the very least unilaterally. If a very low semen volume is encountered on this preoperative semen analysis, transrectal ultrasound should be performed to rule out concomitant ejaculatory duct obstruction. Indicators of spermatogenic dysfunction on physical exam, such as small, soft testicles, should prompt the clinician to obtain a serum follicle stimulating hormone (FSH) level. An elevated FSH level is a marker of poor spermatogenic function and indicates that higher levels of assisted reproductive care may be warranted over the option of VR. It is not recommended to test for serum antisperm antibodies (ASAs) prior to VR, as circulating ASAs are detectable in approximately 60% of men after vasectomy, and the consequence of circulating serum ASAs on fecundability has been challenged considering the high conception rate in couples after VR.


Varicocele patient


As with all diagnoses, the history and physical examination are paramount for the diagnosis of a varicocele. Particularly, the scrotal exam as a varicocele is a diagnosis of physical examination. The testicular volumes should be assessed. Varicoceles are present more frequently on the left due their length on the left side with drainage to the renal vein, rather than directly to the vena cava on the right, accounting for higher hydrostatic pressure in the left spermatic vein with resulting dilation and reflux. , However, 30%–80% of the time, an associated right-sided varicocele is present, but it is most commonly subclinical. Isolated right-sided varicoceles are very rare and should indicate to the clinician to rule out other right-sided retroperitoneal pathology. The classic varicocele is described as feeling like a “bag of worms” on palpation. Men should be examined in the standing and supine positions. Ultrasound is not indicated for the diagnosis of varicocele unless the presence or absence of a varicocele is inconclusive by physical exam.


The laboratory evaluation of men with varicoceles should include a bulk semen analysis with a DNA fragmentation index in select patients, as varicoceles are known to have an adverse impact on both. Varicoceles have been associated with hypogonadism; therefore, the clinician may elect to obtain morning serum testosterone levels on men with varicoceles who present with signs and symptoms of hypogonadism.


Anesthesia


Although local, regional, or general anesthesia may be administered for RAVR to minimize patient movement and to optimize patient comfort, and considering the meticulous nature of tissue handling for this operation, general anesthesia is considered the anesthesia of choice to optimize outcomes. It is possible to perform RAVR under local anesthesia with sedation; however, it is much more challenging due to patient motion while operating on microscopic structures, especially when a more difficult anastomosis or a RAVE is indicated with longer operative times. General anesthesia is also recommended for RAVx to minimize patient motion while ligating microscopic veins and preserving 1-mm gonadal arteries, as well as microscopic lymphatic channels ( Fig. 42.2 ) and the vas deferens.




Fig. 42.2


Magnified view of the spermatic cord with identification of microscopic lymphatic channels.


Patient/robot positioning and settings


For both RAVR and RAVx, the patient is placed supine on the operative table, general anesthesia is induced, all pressure points are padded, and a timeout is performed. The scrotum is shaved, prepared, and draped in a sterile fashion for RAVR (further details on RAVx are described below). Once the vasa are prepared and approximated for the anastomoses, the operative robot is wheeled into position on the patient’s right side at a 90-degree angle to the patient. The camera with a zero-degree lens is positioned directly above the operative field, perpendicular to the ground. Robotic platform settings include a 4× digital zoom, haptic zoom, a close-up working distance setting, and the three-dimensional viewer mode.


Robotic-assisted microsurgical vasectomy reversal


RAVR was initially performed in a laboratory with a human vas deferens ex vivo, reporting an absence of the physiologic tremor often seen under the view of an operative microscope and patency rates similar to those of microsurgical anastomoses, presenting the operative robot as an alternative technology for RAVR. Stability improvement and reduction of extraneous motion during anastomotic suturing was demonstrated with RAVV and RAVE in a rat model. The role of the robotic platform for RAVR further progressed when RAVV was performed in a rabbit model with a multilayered anastomosis with similar patency rates. The first published study on humans undergoing RAVR revealed shorter operative times and early postoperative semen analyses with higher sperm counts than cases performed microsurgically by the same surgeon. A validating study comparing RAVR to microsurgical VR demonstrated similar patency rates, operative times, sperm concentrations, and total motile counts following RAVR. The mean anastomosis time in the RAVV group was statistically longer than the microsurgical group in the early robotic cases; however, the clinical significance of the time difference is debatable as it was a 10-minute difference. The robotic platform offers potential advantages, including a more stable platform, the absence of a physiologic tremor, scaling of motion, ergonomic advantages for the surgeon including less fatigue, three-dimensional high-definition real-time image, the ability of the surgeon to control the camera and three surgical instruments simultaneously, eliminating the need for a microsurgically skilled specialized assistant, and the possibility of decreasing surgical times as caseloads increase. , The robotic platform lends itself to more challenging scenarios such as intraabdominal RAVR for men with vasal obstruction due to previous inguinal hernia mesh or men who underwent laparoscopic vasectomy while having a simultaneous other primary laparoscopic procedure. ,


Robotic-assisted microsurgical vasovasostomy


Incision approaches


A scrotal incision is made to directly access the vasectomy defect, which can be palpated through the scrotal skin, when planning the incision site. The incision may be carried in the direction of the external inguinal ring in cases of lengthy vasectomy defects or high vasectomy defects. Although both vasectomy defects can typically be isolated through one small (1–2 cm) scrotal incision, in cases where the anastomosis must be performed in the more proximal convoluted vas deferens adjacent to the cauda of the epididymis, the incision may be extended, and the testicles may be delivered. VV with a mini-incision using no-scalpel vasectomy principles has been shown to have comparable patency rates with lower postoperative pain scores and more rapid functional recovery. The author’s incision of choice for performing RAVV is a less than 1-cm midline incision to access bilateral vasectomy defects ( Fig. 42.3 ).




Fig. 42.3


The less than 1 cm scrotal incision used for robotic-assisted vasovasostomy.


In men who have undergone prior inguinal herniorrhaphy, with the repair as the suspected etiology of vasal obstruction, performing RAVV inguinally through the scar and mesh of the herniorrhaphy will be extremely challenging. In these cases, successful intraabdominal RAVV has been reported. This is an example of the robotic platform lending itself as an optimal utilization of technology to access an extremely challenging reconstruction and anastomosis. ,


Vas deferens preparation


The vasectomy defect is palpated through the one small scrotal incision, and the testicular and abdominal ends of the bilateral vasa above and below the defects are isolated with vessel loops. The perivasal adventitia should be kept intact and not stripped in order to preserve the microvascular supply to the vas deferens. Fig. 42.4 demonstrates the adventitia with microvasculature intact. While maintaining the adventitia, the testicular and abdominal ends of the vas deferens are mobilized to approximate the ends in a manner that allows for a tension-free anastomosis. The site of the vasectomy defect may be excised or simply excluded, taking great care to preserve the deferential artery during this maneuver. The testicular end of the vas deferens is sharply divided at an exact 90-degree angle. To minimize the risk of fibrosis, scarring, or an irregular edge, the muscularis and mucosa of the divided vas deferens should be closely inspected to confirm a healthy anastomosis site. Vasal fluid is obtained from the testicular end of the vas deferens lumen after transection and is applied to a glass microscope slide and diluted with a small volume of saline and examined with inverted light microscopy. The vasal fluid quality and the microscopic findings direct whether a RAVV or a RAVE should be performed. When whole spermatozoa with tails, regardless of motility, or copious clear vasal fluid is present from the lumen of the testicular end of the vas deferens, even without microscopic visualization of sperm, RAVV is the operation of choice. If no vasal fluid is present, a 24-gauge angiocatheter is cannulated into the testicular end of the vas deferens lumen, and barbotage is performed with 0.1 mL of saline. The barbotaged fluid is then examined under the microscope, with the presence of sperm directing the operation towards RAVV ( Fig. 42.5 ). RAVE should be performed when there is no significant vasal fluid and no sperm are seen in the barbotaged specimen, as well as when the vasal fluid is very thick and toothpaste-like, which usually translates to sperm not being visualized microscopically. Regardless of fluid quality, a 90% or greater patency rate can be expected with VV when sperm fragments, including sperm heads and/or short tails, are microscopically visualized from the vasal fluid. This 90% patency rate exceeds that of VE, making VV the operation of choice when sperm fragments are visualized. , Quality of microscopically visualized sperm has been categorized into five grades. Grade 1: visualization of motile normal sperm; grade 2: mostly normal, non-motile sperm; grade 3: the majority of findings are sperm heads; grade 4: sperm heads only; and grade 5: the complete absence of sperm or sperm fragments. ,




Fig. 42.4


Magnified view of the adventitia of the vas deferens revealing intact microvasculature.



Fig. 42.5


Spermatozoa from the fluid from the testicular end of the vas deferens as seen under inverted light microscopy.


The abdominal end of the vas deferens superior to the vasectomy defect is sharply transected at a 90-degree angle. A 24-gauge angiocatheter is carefully cannulated into the lumen of the abdominal end of the vas deferens, and saline is injected through the lumen to demonstrate patency. Once patency is confirmed, a microspike clamp is used to approximate the abdominal and testicular ends of the vas deferens to prepare for the anastomosis. Another technique to approximate the ends is to carefully place 6-0 polypropylene sutures in the vasal adventitia of both ends as traction for approximation, but this requires help from an assistant. A tongue blade or a metal ruler with a penrose drain covering it is passed under the approximated ends of the vas deferens to create a template on which the anastomosis can be performed. If there is high pressure and saline does not easily inject into the lumen of the abdominal end of the vas deferens when confirming patency, this indicates that another site of obstruction exists, further away in the abdominal end of the vas deferens. A 2-0 propylene suture can be passed gently through the lumen of the abdominal end of the vas deferens to localize the distal obstruction site. If this obstruction site is within 5 cm of the initial vasectomy site, dissection can be performed until the obstruction site is reached and excised to perform a single anastomosis in a tension-free manner with adequate dissection of both ends. This commonly requires an extension of the incision. Performing multiple anastomosis due to multiple sites of obstruction in a single vas deferens is not recommended because of the risk of devascularization, leading to stricture, and failure.


The anastomosis


For acceptable success rates, robotic microsurgical skill is a necessity. The same strict microsurgical technical principles must be adhered to for anastomoses, which will lead to excellent outcomes with RAVR. The mucosa of the lumens of the abdominal and testicular ends of the vas deferens requires perfect approximation. As sperm are extremely antigenic and can induce an inflammatory response with a potential to lead to fibrosis and obstruction with an anastomotic leak of sperm in the general tissue of the scrotum, the anastomosis must be performed in a water-tight fashion ( Fig. 42.6 ). A tension-free anastomosis is paramount for long-term success; therefore, abdominal and testicular vasal segment mobilization without devascularization of the microvasculature is crucial, and placement of reinforcing muscularis sutures helps minimize tension at the anastomosis to optimize long-term patency rates. A successful anastomosis requires a minimal touch technique with as little manipulation of the vasal ends as possible, and not stripping the adventitia of the vas deferens, which may potentially compromise the microvasculature to the vas deferens and result in an anastomotic stricture.


Aug 8, 2022 | Posted by in UROLOGY | Comments Off on Robotic applications for infertility surgeries
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