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Table of Contents
Year : 2018  |  Volume : 29  |  Issue : 4  |  Page : 193-197

Robot-assisted retroperitoneoscopic partial nephrectomy: Comparison of the 3-arm and 4-arm method

1 Department of Surgery, Division of Urology, Chi Mei Medical Center, Tainan, Taiwan
2 Department of Surgery, Division of Uro-Oncology, Chi Mei Medical Center; College of Human Ecology, Chia-Nan University of Pharmacy and Science, Tainan, Taiwan
3 Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan

Date of Web Publication23-Jul-2018

Correspondence Address:
Kau Han Lee
Department of Surgery, Division of Urology, Chi Mei Medical Center, No. 901, Zhonghua Road, Yongkang District, Tainan City 710
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/UROS.UROS_28_18

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Objective: To compare the results from 3-arm and 4-arm robot assisted retroperitoneoscopic partial nephrectomy (RARPN) in our initial case series in terms of oncologic and functional outcomes. Patients and Methods: 35 RARPN performed for malignant small renal masses in our hospital were categorized by the method used, 3-arm or 4-arm. Patient demographics (age, body mass index, tumor size, R.E.N.A.L. nephrometry score, tumor location), perioperative outcomes (operative time, warm ischemic time, estimated blood loss, length of stay, surgical margin status, complications, pathology) and functional outcomes (pre and post operative renal function change) were compared. Results: Initial 14 cases were performed in 3-arm method while latter 21 cases performed in 4-arm method. The tumor size was larger in the 4-arm group (3.5 cm vs 2.3 cm, P = 0.0261) but the warm ischemic time was significant shorter in 4-arm group (17 mins vs 23 mins, P = 0.0093). There were no other significant differences in remaining patient demographics, perioperative outcomes and functional outcomes. Conclusion: 4-arm RARPN is a safe, feasible technique in treating malignant small renal masses even the tumor is located at anterior portion as it provides good traction and exposure on surgical field, thus reducing the warm ischemic time.

Keywords: Partial nephrectomy, robot, retroperitoneoscopic

How to cite this article:
Lim CY, Lee KH, Huang KH, Liu CL, Chiu AW. Robot-assisted retroperitoneoscopic partial nephrectomy: Comparison of the 3-arm and 4-arm method. Urol Sci 2018;29:193-7

How to cite this URL:
Lim CY, Lee KH, Huang KH, Liu CL, Chiu AW. Robot-assisted retroperitoneoscopic partial nephrectomy: Comparison of the 3-arm and 4-arm method. Urol Sci [serial online] 2018 [cited 2023 Sep 25];29:193-7. Available from: https://www.e-urol-sci.com/text.asp?2018/29/4/193/237358

  Introduction Top

Nephron-sparing surgery has been advocated as gold standard in treating small renal tumor mass due to its capability in reducing the risk of progression to chronic kidney disease and in improving the subsequent overall survival in comparison with radical nephrectomy.[1],[2],[3],[4],[5] The transperitoneal approach is favored by the majority of the reported series in open, laparoscopic, and robotic devices as it offers larger working space and more anatomic landmark as compared with that in the retroperitoneal approach.[6],[7],[8] However, the transperitoneal approach has several disadvantages, including manipulation of the posterior tumor, possibility of bowel injury especially in patients with prior abdominal surgery, and subsequent bowel issues. Although retroperitoneoscopic partial nephrectomy was first described by Gaur et al. in 1993,[9] it is not used widely owing to the relatively small working space, less anatomic landmarks, and the requirement of highly advanced laparoscopic skills. Robotic technology can provide precise and easy maneuvers in confined spaces, with excellent three-dimensional (3D) environment as compared with that in the conventional 2D laparoscopic view, which results in a short learning curve in the laparoscopic partial nephrectomy.[10] Most of the reported series on robot-assisted retroperitoneoscopic partial nephrectomy used the 3-arm method, whereas the use of the 4-arm method is rarely described.[11],[12],[13],[14] With the addition of the fourth robotic arm, this method can provide steady traction on key maneuvers such as hilar dissection, tumor excision, and renorrhaphy and gain better exposure of the lesion.[15] These aspects are especially crucial when the tumor is large in volume and located in the upper pole or anteriorly. In this paper, we have presented our experience with robot-assisted retroperitoneoscopic partial nephrectomy and compared the differences between the outcomes of 3-arm and 4-arm approaches.

  Materials and Methods Top

The robotic system was introduced in our hospital in April 2012, and the first robot-assisted retroperitoneoscopic partial nephrectomy was performed in May 2012. After obtaining the institutional review board approval, a total of 35 patients who received robot-assisted retroperitoneoscopic partial nephrectomy for suspected malignant renal tumor were retrospectively evaluated. All robot-assisted retroperitoneoscopic partial nephrectomy was performed by a single surgeon, who is proficient with retroperitoneoscopic surgery. The bedside surgeon was undertaken by residents with varying degrees of robotic experience. The first 14 patients underwent the 3-arm method, whereas the latter 21 patients underwent robot-assisted retroperitoneoscopic partial nephrectomy procedures by the 4-arm method. Patient demographics, preoperative R. E. N. A. L. nephrometry score, operative and perioperative details, and oncological and functional outcomes were retrospectively analyzed. The pre- and post-operative GFRs (6 weeks) were checked using Tc-99 m DTPA. The complications were graded according to the Clavien–Dindo classification.

Surgical procedure

The patient was placed in the full-flank position. The body is fully flexed, with the anterior superior iliac spine positioned over the elevated kidney to allow maximal retroperitoneal space. The dependent arm was padded and secured in an arm board, which was elevated at 30° cephalic to avoid collision with the fourth robotic arm. The lumbar triangle was identified first to serve as an important landmark. A 2 cm length incision for the camera port was created at two fingerbreadths above the iliac crest. A Kelly Forceps was used to penetrate the fascia and enter the retroperitoneal space. A balloon dilator was placed into the retroperitoneum space and then dilated cranial and medially. Next, the first robotic port was placed at a costovertebral angle at 8 cm distance to the camera port under finger guidance. The second robotic port was placed 8 cm medial to the camera port at the anterior axillary line under finger guidance. Before the insertion of the third robotic port and assistant port, the peritoneum was swept off the abdominal wall using blunt intestinal forceps under direct visualization, with 0° robotic lens. The third robotic port was placed at the most medial aspect of the field and slightly higher than the second robotic port to avoid the peritoneal edge. The assistant port was placed 2 cm lateral to the anterior superior iliac spine below the second and third robotic ports [Figure 1]. The Maryland Bipolar Forceps and monopolar curved scissors were routinely used for blunt and sharp dissection in the left and right arms. A ProGrasp Forceps was used in the third robotic arm. A 30° downward pointing robotic lens was used throughout the surgery.
Figure 1: Port placement of the right side RARPN (right: 3-arm, left: 4-arm)

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The first step of the surgery was to develop a plane between the psoas muscle and Gerota's fascia. After the ureter could be readily identified, the fourth arm would be used as the anterior and medial tractions on the kidney. The renal hilum could be dissected using both the robotic arms. The renal artery and segmental artery, if available, is encircled with the vessel loop for identification.

Next, we dissected the renal tumor free from its attachment to the surrounding perinephric fat. A laparoscopic ultrasound probe is used to determine the margin of the tumor and its depth of penetration. Mannitol (12.5 g) was administered 10 min before the resection. The pedicle was clamped using laparoscopic bulldog clamps by the bedside surgeon. The tumor was excised a thermally, and the third robotic arm was deployed to expose the target lesion. The renorrhaphy was performed in two layers, using 15 cm 3-0 and 2-0 Monocryl on the SH needle, with premade knots at the end of the needle. All visible large open vessels and the collecting system were closed with 15 cm 3-0 chromic. Early unclamping and sliding clip technique were used to minimize the warm ischemia time. FloSeal was then applied to the parenchymal defect with surgical covered on it.

The specimen was then bagged and retrieved at the end of the surgery through the assistant port incision. A Jackson–Pratt drain was placed through the fourth robotic port and secured to the skin.

Statistical analysis

Statistical analyses (quantitative and qualitative variables) were performed using Fisher's exact test or Wilcoxon rank sum test. All tests were considered statistically significant at P < 0.05.

  Results Top

Patient demographics and renal tumor details

[Table 1] shows the patient demographic and renal tumor details. A total of 35 patients with suspected malignant small renal mass received robot-assisted retroperitoneoscopic partial nephrectomy. A total of 14 patients were treated by the 3-arm method, whereas 21 patients were treated by the 4-arm method. No statistically significant differences were noted in the patient's age, preoperative and postoperative renal functions, R. E. N. A. L. nephrometry score, or tumor location. The tumor size in the 4-arm group was significantly larger than that in the 3-arm group (P < 0.05).
Table 1: Patient demographics and operative parameters

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Operative details and pathology

No significant difference was noted in the operative time, blood loss, or hospital stays between the groups [Table 2]. However, a significantly shorter warm ischemia time was noted in the 4-arm group. A total of eight patients (22.9%) developed a complication, with two patients undergoing intraoperative blood transfusion. Five patients had Clavien Grade 3 complications (two in the 3-arm group and three in the 4-arm group) that required procedural intervention: Two ureteral stent placements were required to resolve urine leakage, and three pseudoaneurysm formations were required for angioembolization. Moreover, two patients with urine leakage were associated with high R. E. N. A. L. score [Table 3]. No conversions to either traditional laparoscopic or open surgery were noted. One patient (2.9%, 4-arm group) showed positive surgical margin. Majority of the patients had clear cell renal cell carcinoma (62.9%). At a median follow-up of 19 months, no recurrence or distant metastasis was noted.
Table 2: Perioperative outcomes of patients undergoing RARPN

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Table 3: Management of complications (≧ grade 3)

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  Discussion Top

Robot-assisted partial nephrectomy has become popular for treating small renal mass as it provides favorable oncological and functional outcomes to open partial nephrectomy and laparoscopic partial nephrectomy.[16],[17] The retroperitoneal approach partial nephrectomy was suggested for the resection of posteriorly located renal tumors, as it may be faster as compared with the transperitoneal approach. Moreover, the retroperitoneal approach offers direct and rapid access to the renal hilum, which results in shorter operative time and avoidance of possible bowel-related problems.[6],[12],[13],[18],[19]

Most of the reported studies in the robot-assisted retroperitoneoscopic partial nephrectomy used the 3-arm method instead of the 4-arm method, which is usually used in the transperitoneal approach considering that the retroperitoneal space is relatively small.[11],[12],[13],[14] This is the first report on the utilization of four robotic arms in robot-assisted retroperitoneoscopic partial nephrectomy. With the aid of the fourth robotic arm, steadier and accurate traction was obtained on the target tissues as compared with that offered by bedside surgeons. This aspect is especially important when dealing with large, endophytic, or hilar renal tumors. Our series revealed that despite larger and more complicated tumor encountered in the 4-arm group, the operative time and warm ischemic time was shorter in this group than in the 3-arm group and comparable with the previously reported values.[11],[12],[13],[14],[17],[18],[19] The total operative time did not extend with the expansion of the retroperitoneal space for the fourth robotic arm. This can be explained probably by the utilization of the fourth robotic arm and increased familiarity to the procedure. However, it could also be affected by the tumor location in the 4-arm group, as only 24% of the tumors were located at the anterior portion as compared with 50% in the 3-arm group. Comparing the console time for the two groups regarding the tumor locations, no statistically significant difference was noted [Table 4].
Table 4: Comparison of console time with different tumor location

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The majority of the lesions (69%–100%) treated by the robot-assisted retroperitoneoscopic partial nephrectomy in the reported series were located at the posterior portion.[11],[12],[13],[15],[18],[19] Most of the studies suggested treatment of the anterior renal tumor by the transperitoneal approach.[6],[7],[8] In our series, 34% of the tumors were located at the anterior portion, and the subgroup analyses revealed that the perioperative outcomes were comparable with the published large series of robot-assisted transperitoneal partial nephrectomy [Table 5]. However, the included robot-assisted transperitoneal partial nephrectomy cases target not only the anterior tumor but also the posterior tumor. Therefore, the actual situation may be even worse. Nevertheless, with the use of the fourth robotic arm, the retroperitoneal approach to the anterior tumor could be safely managed without compromising the oncological and functional outcomes found in our series. In addition, by plotting the case sequentially versus console time, no difference was noted in the learning curve [Figure 2], owing to the difference in the tumor complexity and location.
Table 5: Subgroup analysis of anterior tumor

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Figure 2: Case sequential of RARPN versus console time

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The limitations of this study include its retrospective nature, the small sample size, and the performance of all surgeries by a single surgeon who is an expert in retroperitoneoscopic surgery. Therefore, the results may not be applicable to the general urology population and for drawing definite conclusions. Moreover, the postsurgical follow-up time was relatively short to evaluate the oncological outcomes, such as tumor recurrence or distant metastasis.

  Conclusions Top

Comparing the 3-arm and 4-arm robotic approaches in robot-assisted retroperitoneoscopic partial nephrectomy provided good traction and exposure on the surgical field, thereby facilitating tumor excision and renorrhaphy, which in turn resulted in short warm ischemic time. As per our experience, this approach is safe, reproducible, and feasible, with good oncological and functional outcomes for treating small renal masses, even in anterior tumors.[23]

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

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  [Figure 1], [Figure 2]

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]


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