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Robotic urologic microsurgery
Introduction
In the field of male reproductive surgery, optical magnification is crucial due to the microscopic anatomic structures. The microsurgeon gains advantages with tools and technology for ease of use and ergonomics. These surgical procedures had fairly poor outcomes due to the limitation of direct visualization by the naked eye prior to the 1970s when the operative microscope began being used. Beyond direct visualization without magnification, optical loupes were utilized; however, the outcomes which are considered acceptable today were not possible until the application of the operative microscope. There were still some unmet needs with the operative microscope, including the surgeon’s ergonomics and comfort, as well as the ability of a single surgeon to have complete autonomy in controlling all steps of the surgery. Male fertility microsurgery is a perfect field for the application of the robotic platform to address some of these challenges. Robotic microsurgery offers potential benefits over surgery with the traditional operative microscope, including less fatigue; better ergonomics; robotic EndoWrists offering seven degrees of freedom, which allow for movements beyond what the human hand and wrist can do; microsurgical scalability of motion; a high-definition three-dimensional visualization of the microsurgical field up to 10 to 15X; an extremely stable platform; elimination of any physiologic tremor; the ability for the surgeon to control three surgical instruments and the camera at once, diminishing the need for microsurgically skilled specialized assistants; and shorter operative times after learning curves are reached. The two most commonly performed male fertility microsurgical procedures are varicocele repair and vasectomy reversal, which lend themselves readily to the application of the robotic platform to meet some of these previously unmet needs for the microsurgeon.
Society has had a longstanding fascination with the concept of humans gaining mechanical advantage in our tasks by the use of robots. Many diverse fields have described interest in this goal; however, it has been realized in surgery. The da Vinci robotic system brought the most advanced robotic platform to date with real-world clinical utility to the forefront to meet this goal. The platform was developed initially for gross surgical procedures and has progressed for use in microsurgery. This robotic system lends itself particularly well to microsurgical male fertility procedures which were traditionally performed with the use of an operative microscope. Such procedures include robot-assisted vasectomy reversal (RAVR) and robot-assisted varicocele repair (RAVx).
With 500,000 men undergoing vasectomy for contraception in the United States annually, approximately 6% (30,000 men) will pursue a vasectomy reversal (VR) for another chance at fatherhood. This frequency of vasectomy reversals in the United States is primarily due a divorce rate of 50%. , VR was initially described in the 1930s, but adequate patency rates were not reported until the 1970s when the operative microscope was applied for magnification of the microscopic anastomosis. The most common diagnosis made in infertile men is varicocele, which is abnormal dilation of the scrotal veins, which has an incidence of approximately 15% of men in the general population and 40% of men presenting for fertility evaluations, as well as being a common diagnosis in men presenting with scrotal pain. Varicocele repair (Vx) has been demonstrated to improve semen parameter values and pregnancy rates. Vx has traditionally been performed with an operative microscope in order to visualize and ligate all the veins that are considered culprits while preserving the gonadal arteries and lymphatics in the spermatic cord. Both VR and Vx were initially performed without the use of magnification tools with only the use of the naked eye, with fairly poor outcomes. As surgical magnification technology progressed, these procedures evolved first with the use of optical loupes, then the operative microscope, and now the robotic platform. The da Vinci system components include the surgeon console and the bedside robotic arms for the camera and selected instrumentation ( Fig. 35.1 ).
Anatomy
A masterful understanding of the male reproductive anatomy is paramount for Vx and VR for safe and successful outcomes. The vas deferens is formed from the extension of the distal end of the cauda of the epididymis. The mesonephric (wolffian) duct is the embryologic origin of the vas deferens. The convoluted vas deferens is the segment of the vas deferens extending from the distal cauda of the epididymis as a tortuous hollow tube, measuring 2 to 3 cm in length. The total length of the vas deferens is 25 to 30 cm, from the distal cauda of the epididymis to its final destination into the ejaculatory duct. The spermatic cord vessels run adjacent to the vas deferens. The vas deferens luminal diameter varies between 0.2 and 0.7 mm depending on the vasal segment. The main blood supply to the vas deferens comes from the deferential artery which is a branch off of the superior vesical artery. The scrotal vas deferens’ venous drainage is via the deferential vein to 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 vas deferens’ lymphatic channels drain into the internal and external iliac lymph nodes.
Transit of sperm occurs from the testis, through the epididymis to the vas deferens. The epididymis is a tightly coiled tubular network and would stretch 12 to 15 feet in length if uncoiled. The three regions of the epididymis include the caput (head), the corpus (body), and the cauda (tail). , The caput of the epididymis is comprised of 8 to 12 ductuli efferentes from the testis. The most distal segment of the cauda of the epididymis becomes the most proximal portion of the vas deferens. The caput and corpus of the epididymis receive arterial supply from branches of the testicular artery. The cauda of the epididymis receives its arterial supply from deferential artery branches. The cauda and corpus of the epididymis have venous drainage via the vena marginalis of Haberer, which ultimately drains into the pampiniform plexus via the vena marginalis of the testis or the cremasteric or deferential veins. The caput and the corpus of the epididymis have their lymphatic drainage via channels traveling adjacent to the internal spermatic vein, which drain into the preaortic nodes. The cauda of the epididymis has lymphatic channels which drain into those draining the vas deferens to the external iliac nodes.
Preoperative assessment
Patient with a varicocele
The history and physical examination are crucial for the diagnosis of a varicocele. The scrotal exam is especially important, as a varicocele is purely a diagnosis of physical examination. Assessment of testicular volumes should be included in the exam. Varicoceles are more common on the left due to greater lengths on the left side with drainage to the renal vein, rather than directly to the vena cava on the right. The longer lengths on the left side result in greater hydrostatic pressure in the left spermatic vein resulting in more significant dilation and venous reflux. , An associated right-sided varicocele is present 30% to 80% of the time but is typically subclinical and not relevant. Isolated right-sided varicoceles are uncommon and should prompt an investigation to rule out other right-sided retroperitoneal pathology resulting in the varicocele. The classic physical description of a varicocele is feeling like a “bag of worms” on palpation. Physical exam should be performed with the patient in the standing and supine positions. Sonography is not indicated for the varicocele diagnosis except for the rare scenario where the examiner is unsure of the presence or absence of a varicocele by physical exam.
Men with varicoceles may undergo a laboratory evaluation including a bulk semen analysis with a DNA fragmentation index in select patients, as varicoceles are known to have an adverse impact on both. Testosterone deficiency has been associated with varicoceles; therefore the morning serum testosterone level may be obtained in men with varicoceles with signs and symptoms consistent with testosterone deficiency.
Vasectomy reversal patient
Men interested in undergoing RAVR should undergo a preoperative evaluation including an estimation of the level of spermatogenesis. A history of proven fertility prior to vasectomy is considered adequate. A physical examination focused on the genital examination should be performed. Normal volume testicles with firm consistency on examination are positive indicators of spermatogenesis, in contrast to small testes with a soft consistency, potentially indicating spermatogenic dysfunction. Palpably dilated epididymides on the exam are common in men who have undergone a vasectomy. Epididymal induration may reveal a level of obstruction of the epididymis and may predict the need for robot-assisted vasoepididymostomy (RAVE). When the vasectomy gaps are found to be lengthy on palpation, this is a predictor that a larger incision and a more extensive dissection may be necessary for the anastomosis to be performed in a tension-free manner. A sperm granuloma which is palpable at the testicular end of the vasectomy gap is correlated with improved VR outcomes. This is due to the granuloma being resultant of sperm extravasation due to a pop-off valve-like mechanism to reduce intra-epididymal pressures to protect the ductal system. An unconventional incisional may be predictable with an extremely lengthy palpable vasectomy defect. As older men continue to desire VR for another opportunity to father children, and more men are being diagnosed with testosterone deficiency at younger ages, the use of testosterone replacement therapy should be elucidated in the history with its known suppressive impact on spermatogenesis. Men being treated with 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 least 3 months before proceeding with RAVR.
The complexity of repair required during the RAVR may be impacted by the obstructive interval since vasectomy, necessitating robot-assisted vasovasostomy (RAVV) versus RAVE. Typically, longer obstructive intervals are associated with lower patency rates and may require a more challenging technical reconstruction during RAVR. , RAVR may still be offered to men with longer obstructive intervals with technical proficiency and acceptable outcomes in the hands of technically skilled, experienced microsurgeons, and should allow for high patency rates regardless of the need for RAVV or RAVE in men with obstructive intervals longer than 10 years. Nomograms exist to predict which patients might require vasovasostomy (VV) versus vasoepididymostomy (VE) preoperatively, by evaluating factors including age, testicular volumes, the presence of a sperm granuloma, and the obstructive interval. , The data on nomograms, ability to do so accurately has been inconsistent, and some data indicates these nomograms are ineffective at truly predicting which type of reconstruction will be required. , This suggests that only surgeons proficiently trained and skilled in performing both VV and VE perform VRs. , A fertility evaluation for the female partner of the man desiring VR is recommended to assess tubal status and ovarian reserve prior to confirming that VR is the optimal route toward conception for these couples. ,
Prior to VR, a semen analysis with an examination of the centrifuged pellet may be done, although it is not a typical practice. Whole sperm is found in the centrifuged pellet 10% of the time, predicting that sperm will likely be found in the fluid from the vas deferens intraoperatively, at least unilaterally. If the preoperative semen analysis reveals a very low semen volume, transrectal ultrasound can rule out a simultaneous ejaculatory duct obstruction. Small, soft testicles on physical examination are indicators of spermatogenic dysfunction and prompt the clinician to have a serum follicle stimulating hormone (FSH) drawn. When FSH levels are elevated, this indicates spermatogenic dysfunction and suggest, that higher levels of assisted reproductive care may be indicated rather than VR. It is not recommended to obtain serum antisperm antibodies prior to VR, as serum antisperm antibodies are present in around 60% of men who have had a vasectomy. Circulating serum ASAs, impact on fecundability has been refuted considering the high conception rate following VR.
Anesthesia
It is recommended that RAVx is performed under general anesthesia to minimize patient motion while ligating microscopic veins and preserving gonadal arteries which are no larger than 1 mm in diameter ( Fig. 35.2 ), as well as microscopic lymphatic channels, and the vas deferens. Although RAVR may be performed under local, regional, or general anesthesia, general anesthesia is recommended to minimize patient movement and to help with patient comfort. General anesthesia is considered the anesthesia of choice, considering the fine level of tissue handling required for success. RAVR may be performed with the administration of local anesthesia with sedation; however, this adds the challenge of patient motion to the already technical challenge of operating on microscopic structures, particularly when a more complex anastomosis or a RAVE is needed with inherently lengthier operative times.
Patient/robot positioning and settings
When positioning for either RAVx or RAVR, the patient is placed in the supine position, general anesthesia is administered, all pressure points are padded, and a time-out is performed. The scrotum is shaved, prepared, and draped in a sterile fashion for RAVR, as is the subinguinal region and the genitalia for RAVx. For RAVR, after 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 same is done for RAVx after the spermatic cord is isolated and the portion selected for repair is elevated through the subinguinal incision. The camera with a zero-degree lens is placed directly above the operative field, perpendicular to the floor. Settings for the robotic platform are entered, including a 4× digital zoom, haptic zoom, a close-up working distance setting, and the three-dimensional viewer mode.
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