This article provides an overview of extirpative laparoscopic and robotic procedures used in the management of renal cell carcinoma, including laparoscopic radical nephrectomy, laparoscopic partial nephrectomy, and robotic-assisted partial nephrectomy. The clinical indications and principles of surgical technique for each of these procedures are discussed. The oncologic, renal functional, and perioperative outcomes of these procedures are also assessed and compared, as are complication rates.
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Laparoscopic renal surgery is associated with decreased blood loss, shorter hospital stay, improved cosmesis, and more rapid convalescence relative to open renal surgery.
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Laparoscopic partial nephrectomy is a minimally invasive, nephron-sparing alternative to laparoscopic radical nephrectomy for the treatment of small renal masses.
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While offering similar oncologic outcomes to laparoscopic radical nephrectomy, the technical challenges and steep learning curve associated with laparoscopic partial nephrectomy limits its wider dissemination.
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Robot-assisted partial nephrectomy, although still an evolving procedure with no long-term data, has emerged as a viable alternative to laparoscopic partial nephrectomy, with favorable initial outcomes.
Introduction
Because of the increased detection of small renal masses on abdominal imaging, the incidence of renal cell carcinoma has increased significantly in recent years. Accompanying this trend is a clear stage migration favoring stage I tumors and a significant decrease in tumor size even within the stage I group. By 2007, 13.5% of newly diagnosed renal tumors measured less than 2 cm, 37% less than 3 cm, and close to 60% less than 4 cm.
The gold standard for the treatment of renal tumors traditionally has been radical nephrectomy. Investigation over the last decade, however, has found the surgical feasibility and equivalent oncologic efficacy of partial nephrectomy for small renal masses. Furthermore, a growing body of evidence has suggested that overtreatment of renal masses with radical nephrectomy is associated with increased risk of chronic renal insufficiency, cardiovascular events, and premature deaths. Accordingly, the American Urological Association guidelines now explicitly place partial nephrectomy as the standard of care for managing T1a renal tumors (<4 cm) and as an alternative treatment option for T1b tumors (4–7 cm). Reflecting this paradigm shift, the use of partial nephrectomy has increased substantially at many centers of excellence over the last decade, approaching 90% for T1a tumors at some centers. Nevertheless, radical nephrectomy remains the standard of care for managing tumors greater than 7 cm in size, tumors extending into the renal vein, and tumors invading Gerota’s fascia or adjacent organs.
In 1990, Clayman and colleagues performed the first laparoscopic radical nephrectomy (LRN), showing the feasibility of this minimally invasive alternative to open radical nephrectomy (ORN). With the rapid uptake of minimally invasive technology by the urologic community, laparoscopic partial nephrectomy (LPN), first reported in 1993, and robot-assisted partial nephrectomy (RAPN), first performed in 2004, emerged as viable alternatives to open partial nephrectomy (OPN) for the management of suspected renal malignancy. The long-term oncologic and functional outcomes of minimally invasive renal surgery are comparable with those of open renal surgery, with the potential benefits of estimated blood loss (EBL), shorter hospital stay (LOS), improved cosmesis, and more rapid convalescence. Herein, we review the technique and outcomes of LRN, LPN, and RAPN, evaluating the current role and future prospects of each of these approaches for the treatment of renal malignancy.
Laparoscopic radical nephrectomy
Principles in Surgical Technique
LRN can be performed for most patients with organ-confined T1–T3a renal tumors who are not candidates for nephron-sparing surgery. Previously considered contraindications to LRN, larger organ-confined tumors and tumors with renal vein thrombus may be amenable to a laparoscopic approach, depending on individual surgeon experience.
Preoperative assessment of pulmonary and cardiac function before LRN (and minimally invasive renal surgery in general) is essential, as the pneumoperitoneum, combined with the lateral decubitus position characteristic of minimally invasive renal surgery, can impact patients with severe cardiopulmonary disease by compromising ventilation and venous return. Patients with chronic pulmonary disease may be unable to compensate for pneumoperitoneum-induced hypercarbia and may require lowering of pneumoperitoneum pressures, use of helium as an insufflant, or open conversion.
A transperitoneal or retroperitoneal approach is chosen depending on tumor location, patient surgical history, and surgeon preference. Although safe and effective in experienced hands, the retroperitoneal approach is potentially more challenging because of its confined workspace and relatively fewer anatomic landmarks. The transperitoneal approach is the most widely used approach for minimally invasive renal surgery.
The most commonly used camera and trocar configuration for the transperitoneal approach places the camera in a medial position, superior to the umbilicus; a 30° downward-angled lens is used. Two additional trocars are placed just cephalad of the anterior superior iliac spine and a few centimeters below the costal margin in the midaxillary line. During transperitoneal LRN, the peritoneum is incised sharply along the line of Toldt and the bowel mobilized medially, thus developing the avascular plane between Gerota’s fascia and the posterior mesocolon. For right-sided tumors, mobilization of the duodenum may be necessary. Attachments between the renal upper pole and the liver/spleen are then released. Further medial reflection of the mesentery exposes the ureter and gonadal vein. The ureter is lifted, exposing the psoas muscle, and the dissection is continued proximally toward the renal hilum. The renal vein can be identified by tracing the gonadal vein cranially to its insertion in the renal vein on the left side and the inferior vena cava, in proximity to the right renal vein, on the right side. With the kidney on stretch, the renal vein and more posteriorly located renal artery are dissected. The renal artery and, subsequently, renal vein are clipped and transected. Importantly, large hilar tumors distorting the renal hilum must be approached cautiously to avoid transection of aberrant major aortic branches. The ureter is then clipped and transected.
For retroperitoneal LRN, access is obtained through a 1.2-cm skin incision just below the tip of the 12th rib. The flank muscle fibers and thoracolumbar fascia are bluntly split, and the surgeon’s fingertip creates a potential space between the psoas muscle and Gerota’s fascia; this space is further developed by injection of 800 mL of air into the retroperitoneum through a balloon dilator. The camera port is then placed at the site of the balloon dilator. Two additional working ports are triangulated with the camera at an obtuse angle to minimize clashing of the instruments. When performing retroperitoneal LRN, the renal hilum is approached posteriorly after development of a working space between Gerota’s fascia and the psoas muscle and subsequent exposure of the ureter and gonadal vein. In contrast to the transperitoneal approach, the renal artery is usually encountered before the renal vein during retroperitoneal LRN given the posterior relationship of the artery to the vein.
Established guidelines for renal cancer surgery, including preservation of tumor integrity and Gerota’s fascia, must be applied to achieve the best oncologic outcomes. To avoid contact with the abdominal wall, the excised surgical specimen must be removed in an impermeable sac. Either intact specimen extraction or specimen morcellation may be performed safely, although extreme caution must be exercised to avoid sac perforation with potential tumor spillage if morcellation is to be performed.
Oncologic Outcomes
The oncologic efficacy of LRN seems to be equivalent to that of the traditional ORN. In a multicenter study comparing the oncologic outcomes of 64 patients who underwent LRN with 69 patients who underwent ORN, Portis and colleagues reported a Kaplan-Meier–estimated 5-year disease-free survival of 92% and 91%, respectively; respective cancer specific survival was 98% versus 92%. The authors concluded that LRN does not increase the risk of local tumor recurrence or distant metastasis.
LRN does not seem to result in a significant risk of port-site seeding. In a comprehensive review of port-site metastasis in urologic surgery, Tsivian and Sidi found only 3 documented cases of port-site metastasis following LRN for renal cell carcinoma. The authors note that 2 of those cases occurred in patients who had undergone specimen morcellation before extraction, although the role of morcellation in contributing to these rare cases of port-site recurrences is debatable. Others have reported that specimen morcellation does not confer an increased risk for port-site seeding when proper surgical technique is adhered to.
Functional Outcomes
Comparing the renal functional outcomes of LRN and OPN for tumors measuring ≤4 cm, Matin and colleagues noted that patients who underwent nephron-sparing surgery experienced less postoperative deterioration in renal function, as determined by the percentage of increase in serum creatinine level postoperatively (0% in the OPN group vs 25% in the LRN group, P <.001).
Regardless of surgical technique (ie, minimally invasive vs open), radical nephrectomy is clearly associated with inferior renal functional outcomes relative to partial nephrectomy. A Memorial Sloan Kettering study examining 3-year renal functional outcomes in patients undergoing radical nephrectomy versus those undergoing partial nephrectomy found a 65% probability of the development of new-onset stage 3 or higher chronic kidney disease in the radical nephrectomy group compared with a 20% probability in the partial nephrectomy group ( P <.0001).
Perioperative Outcomes
LRN is clearly associated with decreased EBL, decreased LOS, and more rapid convalescence relative to ORN. A comparative perioperative assessment of 33 patients with T2 tumors (≥7 cm) who underwent LRN at the Cleveland Clinic and 34 patients who underwent ORN for tumors of similar stage at the same institution found a mean EBL of 294 mL in the laparoscopic group, compared with 837 mL in the open group; mean LOS was 1.8 days in the LRN group versus 6.1 days in the ORN cohort.
A more recent comparison of 65 patients with T2 renal tumors who underwent LRN and 34 patients with tumors of equivalent stage who underwent ORN found decreased analgesic requirements ( P <.001) and more rapid convalescence ( P = .02) in the LRN group.
Complications
Reported complication rates can vary substantially depending on prospective versus retrospective reporting and the appropriate use of standardized classification criteria. Nevertheless, LRN is generally associated with a low incidence of complications when performed by surgeons experienced in minimally invasive techniques. Siqueira and colleagues reported a major complication rate of 4% in their review of 61 LRN cases; these included one vascular complication, one hemorrhagic complication, one visceral injury (liver injury during port placement), and one bowel injury. Steinberg and colleagues reported a complication rate of 6.2% in 33 patient undergoing LRN for T2 tumors versus a complication rate of 23.5% in 34 patients undergoing ORN for tumors of equivalent stage, although the difference was not statistically significant.
Laparoscopic radical nephrectomy
Principles in Surgical Technique
LRN can be performed for most patients with organ-confined T1–T3a renal tumors who are not candidates for nephron-sparing surgery. Previously considered contraindications to LRN, larger organ-confined tumors and tumors with renal vein thrombus may be amenable to a laparoscopic approach, depending on individual surgeon experience.
Preoperative assessment of pulmonary and cardiac function before LRN (and minimally invasive renal surgery in general) is essential, as the pneumoperitoneum, combined with the lateral decubitus position characteristic of minimally invasive renal surgery, can impact patients with severe cardiopulmonary disease by compromising ventilation and venous return. Patients with chronic pulmonary disease may be unable to compensate for pneumoperitoneum-induced hypercarbia and may require lowering of pneumoperitoneum pressures, use of helium as an insufflant, or open conversion.
A transperitoneal or retroperitoneal approach is chosen depending on tumor location, patient surgical history, and surgeon preference. Although safe and effective in experienced hands, the retroperitoneal approach is potentially more challenging because of its confined workspace and relatively fewer anatomic landmarks. The transperitoneal approach is the most widely used approach for minimally invasive renal surgery.
The most commonly used camera and trocar configuration for the transperitoneal approach places the camera in a medial position, superior to the umbilicus; a 30° downward-angled lens is used. Two additional trocars are placed just cephalad of the anterior superior iliac spine and a few centimeters below the costal margin in the midaxillary line. During transperitoneal LRN, the peritoneum is incised sharply along the line of Toldt and the bowel mobilized medially, thus developing the avascular plane between Gerota’s fascia and the posterior mesocolon. For right-sided tumors, mobilization of the duodenum may be necessary. Attachments between the renal upper pole and the liver/spleen are then released. Further medial reflection of the mesentery exposes the ureter and gonadal vein. The ureter is lifted, exposing the psoas muscle, and the dissection is continued proximally toward the renal hilum. The renal vein can be identified by tracing the gonadal vein cranially to its insertion in the renal vein on the left side and the inferior vena cava, in proximity to the right renal vein, on the right side. With the kidney on stretch, the renal vein and more posteriorly located renal artery are dissected. The renal artery and, subsequently, renal vein are clipped and transected. Importantly, large hilar tumors distorting the renal hilum must be approached cautiously to avoid transection of aberrant major aortic branches. The ureter is then clipped and transected.
For retroperitoneal LRN, access is obtained through a 1.2-cm skin incision just below the tip of the 12th rib. The flank muscle fibers and thoracolumbar fascia are bluntly split, and the surgeon’s fingertip creates a potential space between the psoas muscle and Gerota’s fascia; this space is further developed by injection of 800 mL of air into the retroperitoneum through a balloon dilator. The camera port is then placed at the site of the balloon dilator. Two additional working ports are triangulated with the camera at an obtuse angle to minimize clashing of the instruments. When performing retroperitoneal LRN, the renal hilum is approached posteriorly after development of a working space between Gerota’s fascia and the psoas muscle and subsequent exposure of the ureter and gonadal vein. In contrast to the transperitoneal approach, the renal artery is usually encountered before the renal vein during retroperitoneal LRN given the posterior relationship of the artery to the vein.
Established guidelines for renal cancer surgery, including preservation of tumor integrity and Gerota’s fascia, must be applied to achieve the best oncologic outcomes. To avoid contact with the abdominal wall, the excised surgical specimen must be removed in an impermeable sac. Either intact specimen extraction or specimen morcellation may be performed safely, although extreme caution must be exercised to avoid sac perforation with potential tumor spillage if morcellation is to be performed.
Oncologic Outcomes
The oncologic efficacy of LRN seems to be equivalent to that of the traditional ORN. In a multicenter study comparing the oncologic outcomes of 64 patients who underwent LRN with 69 patients who underwent ORN, Portis and colleagues reported a Kaplan-Meier–estimated 5-year disease-free survival of 92% and 91%, respectively; respective cancer specific survival was 98% versus 92%. The authors concluded that LRN does not increase the risk of local tumor recurrence or distant metastasis.
LRN does not seem to result in a significant risk of port-site seeding. In a comprehensive review of port-site metastasis in urologic surgery, Tsivian and Sidi found only 3 documented cases of port-site metastasis following LRN for renal cell carcinoma. The authors note that 2 of those cases occurred in patients who had undergone specimen morcellation before extraction, although the role of morcellation in contributing to these rare cases of port-site recurrences is debatable. Others have reported that specimen morcellation does not confer an increased risk for port-site seeding when proper surgical technique is adhered to.
Functional Outcomes
Comparing the renal functional outcomes of LRN and OPN for tumors measuring ≤4 cm, Matin and colleagues noted that patients who underwent nephron-sparing surgery experienced less postoperative deterioration in renal function, as determined by the percentage of increase in serum creatinine level postoperatively (0% in the OPN group vs 25% in the LRN group, P <.001).
Regardless of surgical technique (ie, minimally invasive vs open), radical nephrectomy is clearly associated with inferior renal functional outcomes relative to partial nephrectomy. A Memorial Sloan Kettering study examining 3-year renal functional outcomes in patients undergoing radical nephrectomy versus those undergoing partial nephrectomy found a 65% probability of the development of new-onset stage 3 or higher chronic kidney disease in the radical nephrectomy group compared with a 20% probability in the partial nephrectomy group ( P <.0001).
Perioperative Outcomes
LRN is clearly associated with decreased EBL, decreased LOS, and more rapid convalescence relative to ORN. A comparative perioperative assessment of 33 patients with T2 tumors (≥7 cm) who underwent LRN at the Cleveland Clinic and 34 patients who underwent ORN for tumors of similar stage at the same institution found a mean EBL of 294 mL in the laparoscopic group, compared with 837 mL in the open group; mean LOS was 1.8 days in the LRN group versus 6.1 days in the ORN cohort.
A more recent comparison of 65 patients with T2 renal tumors who underwent LRN and 34 patients with tumors of equivalent stage who underwent ORN found decreased analgesic requirements ( P <.001) and more rapid convalescence ( P = .02) in the LRN group.
Complications
Reported complication rates can vary substantially depending on prospective versus retrospective reporting and the appropriate use of standardized classification criteria. Nevertheless, LRN is generally associated with a low incidence of complications when performed by surgeons experienced in minimally invasive techniques. Siqueira and colleagues reported a major complication rate of 4% in their review of 61 LRN cases; these included one vascular complication, one hemorrhagic complication, one visceral injury (liver injury during port placement), and one bowel injury. Steinberg and colleagues reported a complication rate of 6.2% in 33 patient undergoing LRN for T2 tumors versus a complication rate of 23.5% in 34 patients undergoing ORN for tumors of equivalent stage, although the difference was not statistically significant.
Laparoscopic partial nephrectomy
Principles in Surgical Technique
Patient positioning, port placement, and kidney exposure during LPN follow the same principles as those for LRN. In contrast to LRN, Gerota’s fascial must be incised and the perirenal fat swept away from the kidney during LPN to gain full exposure of the renal tumor. Care must be taken to preserve the fat directly overlying the renal lesion in anticipation of extracapsular tumor extension. With the tumor exposed, the precise position and borders of the tumor are delineated, often under intraoperative ultrasound guidance.
Traditionally, renal hilar vessels are clamped before tumor excision during partial nephrectomy. In contrast to OPN, which often is performed under conditions of renal hypothermia to minimize ischemic insult to the clamped kidney, minimally invasive techniques for achieving renal hypothermia during renal hilar clamping have failed to achieve widespread clinical application.
In recognition of the potential impact that even a limited duration of warm ischemia time may have on renal function, variations in surgical technique have been attempted to minimize or eliminate warm ischemia during LPN. Some investigators have adopted an early unclamping technique, whereby the hilar vessels are only clamped during sharp dissection of the tumor from kidney and while suturing obvious vessels and the collecting system at the resection base. Gill and colleagues were able to decrease their warm ischemia time for LPN from 31.6 to 14.4 minutes using this technique. Others have described successful use of a selective renal parenchymal clamping technique, whereby the renal parenchyma is regionally clamped only in the area of the planned excision. Benway and colleagues reported improved renal functional outcomes with segmental rather than complete hilar clamping in a porcine model, whereas Figenshau showed the safety and feasibility of this technique in humans. More recently, some surgeons have performed LPN without any clamping of the renal hilum, often in the setting of medically induced hypotension, and have suggested that off-clamp, zero-ischemia, LPN can be safely performed in carefully selected patients. Nevertheless, multiple studies in humans have failed to demonstrate long-term improvement in renal functional outcomes after any modification of clamping technique or in the absence of renal hilar clamping. Additional studies are needed to establish the efficacy and reaffirm the safety of these unconventional and, arguably, still experimental surgical approaches.
Traditionally, 12.5 g of mannitol is administered intravenously 15–20 minutes before renal hilar clamping, because this is believed to minimize reperfusion injury after release of the renal vascular clamps. Tumor excision is performed sharply with a rim of normal renal parenchyma, with simultaneous use of electrocautery to facilitate hemostasis. Hemostatic agents, such as gelatin matrix thrombin sealant (Floseal, Baxter; Deerfield, IL), may aid in achieving hemostasis, although larger vessels at the resection base may necessitate sutured vascular repair.
After tumor excision, renorrhaphy is traditionally performed in 2 layers. A deep-layer closure of the resection bed, including repair of large blood vessels or any collecting system defects, is first performed, followed by an outer layer closure of the renal capsule. To enhance the tension of the parenchymal closure, surgical bolsters are generally placed in the renal defect after the deep layer closure and before the outer layer closure. Knotless renorrhaphy using Weck Hem-O-Lock clips (Weck Closure Systems, Research Triangle Park, NC, USA) to anchor the capsular sutures on opposite sides of the renal defect has been adopted by some to expedite the closure and, thus, reduce warm ischemia time. Importantly, absorbable suture must be used during renal reconstruction, because nonabsorbable suture may serve as a nidus for stone formation.
LPN remains technically challenging, requiring considerable technical expertise to achieve adequate tumor resection, pelvicaliceal reconstruction, and parenchymal renorrhaphy while maintaining hemostasis and minimizing ischemia times during hilar clamping. Despite the development of novel techniques to facilitate LPN by expert laparoscopic surgeons, the steep learning curve associated with this technique has impeded its wider dissemination into general practices in the United States and may contribute to the underutilization of partial nephrectomy.
Given its technical challenges, LPN traditionally has been performed in select patients with small, exophytic, easily accessible tumors, although successful and safe application of this technique has been described for larger, more complex tumors by expert minimally invasive surgeons.
Oncologic Outcomes
In a study by Gill and colleagues comparing 100 early cases of LPN (median tumor size 2.8 cm) with 100 cases of OPN (median tumor size 3.3 cm), positive parenchymal margin occurred in 2 cases of LPN versus zero cases of OPN; of note, no patients in the LPN group had local tumor recurrence.
More recently, Gill and colleagues compared the 3-year oncologic outcomes of 514 patients who underwent LPN and 676 patients who underwent OPN and had a Kaplan-Meier-estimated 3-year cancer specific survival of 99.3% and 99.2%, respectively. Kaplan-Meier-estimates of local recurrence were 1.4% versus 1.5%, whereas estimates of distant recurrence were 0.9% versus 2.1%, respectively.
Long-term oncologic outcomes from the largest series of LPN were recently reported by Lane and colleagues and were comparable with those of OPN. At 7-year follow-up, metastasis-free survival was 97.5% in the LPN group versus 97.3% in the OPN group ( P = .47). Using propensity score matching to account for baseline differences between the 2 cohorts, 7-year metastasis-free survival was similar after LPN and OPN. On multivariate analysis, surgical approach (LPN vs OPN) failed to predict all-cause morality.
Functional Outcomes
Comparing a cohort of 100 patients who underwent LPN with a cohort of 100 patients who underwent OPN—each with similar preoperative serum creatinine levels (1.0 vs 1.0 mg/dL, P = .52)—Gill and colleagues reported no difference in postoperative serum creatinine level between the 2 groups (1.1 vs 1.2 mg/dL, P = .65).
In a more recent multicenter comparison of 771 patients who underwent LPN and 1028 patients who underwent OPN, Gill and colleagues reported similar renal functional outcomes 3 months postoperatively for the patient cohort. In the LPN group, mean preoperative serum creatinine level was 1.01 compared with 1.18 postoperatively; in the OPN group, mean preoperative serum creatinine level was 1.25, compared with 1.42 postoperatively. Of note, in the subset of patients with a solitary kidney, a statistically significant advantage in renal preservation favored the OPN approach over the LPN approach. Patients with a solitary kidney who underwent LPN had a mean preoperative serum creatinine value of 1.24 versus 1.90 postoperatively, whereas those who underwent OPN had a mean preoperative creatinine value of 1.32 compared with 1.73 postoperatively. These results raise concerns about the appropriateness of the LPN approach in patients with a solitary kidney or compromised baseline renal function.
Perioperative Outcomes
In a study of 50 LPNs performed for tumors with a mean size of 3 cm, investigators reported a mean warm ischemia time of 23 minutes, a mean operating time of 3 hours, and a mean LOS of 2.2 days. In the study by Gill and colleagues, comparing 100 cases of LPN with 100 cases of OPN, mean operating time was 3 hours versus 3.9 hours, respectively; mean warm ischemia time was 28 versus 18 minutes; mean EBL was 125 mL versus 250 mL; mean LOS was 2 days versus 5 days; mean analgesic requirement was 20.2 mg morphine sulfate equivalent versus 252.5 mg; average convalescence was 4 weeks versus 6 weeks. This study found a clear advantage in postoperative recovery favoring the LPN approach over the OPN approach.
Similar findings were reported in the more recent analysis by Gill and colleagues of 771 patients who underwent LPN and 1028 patients who underwent OPN. In this study, a mean operating time of 3.3 hours was noted in the LPN group compared with 4.3 hours in the OPN group. Mean warm ischemia time was 30.7 and 20.1 minutes in the 2 groups, respectively. Mean EBL was 300 mL in the LPN group versus 376 mL in the open group. Mean LOS was 3.3 days and 5.8 days, respectively.
Complications
An international literature review of 97 patients undergoing LPN found a major complication rate of 10%. In a multicenter European study of 53 patients undergoing LPN, intraoperative bleeding was reported in 8% of patients; postoperative bleeding was noted in 2% of patients, whereas postoperative urinoma was reported in 10% of patients. Conversion to open surgery was required in 4% of patients secondary to bleeding and in 4% secondary to technical problems. Reintervention via percutaneous nephrostomy drainage occurred in 4% of patients, 2% of patients required postoperative stent placement, 4% required open revision, and 2% required nephrectomy.
In their comparative study of 100 LPN cases and 100 OPN cases, Gill and colleagues reported no difference in the overall incidence of postoperative complications between the 2 groups (16% vs 13%, P = .55). However, compared with the OPN group, the LPN cohort had a higher incidence of intraoperative complications (5% vs 0%; P = .02) as well as urologic postoperative complications (11% vs 2%; P = .01).
In their more recent comparison of 771 patients who underwent LPN and 1028 patients who underwent OPN, Gill and colleagues reported an intraoperative complication rate of 1.8% in the LPN group versus 1.0% in the OPN group; the postoperative complication rate was 18.6% in the LPN group and 13.7% in the OPN group. On multivariate analysis, the odds of a postoperative complication after LPN were 1.66 (95% confidence interval [CI], 1.33–2.05) times higher than those after OPN. The odds of urologic complications were 2.14 (95% CI, 1.39–3.31) higher for LPN than for OPN, whereas the odds of nonurologic complications were 1.53 (95% CI, 1.12–2.10) higher in the LPN group. A postoperative hemorrhage rate of 4.2% was noted in the LPN group compared with 1.6% in the OPN group. On multivariate analysis, the odds of postoperative hemorrhage after LPN were 3.53 (95% CI, 1.88–4.94) times higher than for OPN. The blood transfusion rate was 5.8% in the LPN group versus 3.4% in the OPN group. Postoperative urine leakage occurred in 3.1% of patients in the LPN group compared with 2.3% in the OPN group. The odds of requiring a secondary procedure for any reason were 3.05 (95% CI, 1.88, 4.94) times higher in the LPN group than in the OPN group. Based on these cumulative results, this large multicenter study shows that LPN is, in fact, associated with increased risk of complications relative to OPN, even in expert hands.
Robot-assisted partial nephrectomy
Principles in Surgical Technique
RAPN is performed using the da Vinci surgical system (Intuitive Surgical Inc, Sunnyvale, CA). Among its potential advantages, robotic technology offers high-definition, 3-dimensional visualization, a wider range of wristed-instrument motion, and scaling of surgeon movements. Newer robotic systems also include a fourth robotic arm (in addition to the camera arm and 2 standard working arms), which provides the surgeon an additional working channel. Nevertheless, the robotic surgeon must rely on a bedside assistant to facilitate the surgery by using conventional laparoscopic instruments to provide countertraction and suction through an additional assistant port.
As with LRN and LPN, in RAPN, a camera port is placed medial and superior to the umbilicus, and 2 trocars for the robotic arms are placed just cephalad of the anterior superior iliac spine and below the costal margin along the midaxillary line. Unique to RAPN, an additional 12-mm assistant port is placed in the midline, usually inferior to the umbilicus, although the surgeon may elect to place the assistant port in the upper quadrant depending on tumor location. If a fourth robotic arm is to be used, the trocar is placed laterally, triangulated between the 2 other robotic trocars. The robot is then docked posterior to the patient.
The technique for RAPN, although similar to that of LPN, continues to evolve. Our current approach uses the newly developed robot-controlled ultrasound probe (Aloka, Tokyo, Japan), which allows complete surgeon control of intraoperative imaging, thereby facilitating tumor identification and delineation of the resection site. Newer robotic platforms also include TilePro software integration (Intuitive Surgical Inc, Sunnyvale, CA, USA), which allows for real-time picture-on-picture display of radiographic images on the console screen, further facilitating the mapping out of the dissection. The recent introduction of robotic Bulldog clamps may provide the surgeon additional autonomy, in lieu of having to relegate the sensitive task of hilar occlusion to the bedside assistant.
Sliding-clip renorrhaphy has been described recently as a preferable alternative to the traditional tied-suture for closure of the renal defect during RAPN. This renorrhaphy method relies on the use of Weck Hem-o-Lok clips (Weck Closure Systems, Research Triangle Park, NC, USA), placed on either side of the defect and then slid into place by the surgeon to exert tension on the repair. The Hem-o-Lok clips are generally reinforced with LapraTy clips (Ethicon; Cincinnati, OH) to prevent backsliding of the clips. Although the use of Weck Hem-o-Lok clips to facilitate renorrhaphy has been applied to LPN, the sliding-clip technique described for RAPN differs from earlier laparoscopic applications in that the surgeon controls the tension of the closure by sliding the clips into the desired position, effectively eliminating the need for placement of surgical bolsters in the renal defect to achieve tight closure. This technique is ideally suited for RAPN, as the robotic instrumentation affords the surgeon the requisite precision in dictating the degree of tension placed on the repair. By simplifying the closure, while minimizing reliance on the assistant, sliding-clip renorrhaphy has been found to substantially reduce warm ischemia time compared with tied-suture renorrhaphy. A recently described variation of the sliding-clip technique is the use of barbed suture (V-loc, Covidien; Mansfield, MA) to facilitate efficient and tight renorrhaphy without slippage of sutures or clips.
RAPN seems to have a shorter learning curve than LPN and, as such, may facilitate and promote the use of minimally invasive nephron-sparing surgery. Numerous reports describe the intraoperative and perioperative outcomes of RAPN, compare the experiences of RAPN with those of LPN, and describe the utility of RAPN in the management of complex renal masses. Nevertheless, for the inexperienced robotic renal surgeon, careful patient selection is essential. The absence of haptic feedback and reliance on the bedside assistant can present challenges unique to RAPN. Candidates ideally suited for initial RAPN procedures include patients with predominantly nonhilar, exophytic T1a lesions, uncomplicated vascular anatomy, and a normal contralateral kidney.
Oncologic Outcomes
Because RAPN is a newer technique, positive surgical margin rates have often been reported as surrogates for oncologic control. Reported positive surgical margin rates for RAPN have typically ranged from 1.2% to 5.7%. A review of contemporary RAPN series by Benway and Bhayani found that the comprehensive surgical margin rate across all studies reviewed was 2.7%. These rates are comparable with those reported by Gill and colleagues for LPN and OPN—2.9% and 1.3%, respectively. Positive margin rates in various RAPN series are depicted in Table 1 , and studies comparing positive margin rates between RAPN and LPN are depicted in Table 2 .
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