Introduction
Up to 5–10% of urothelial carcinoma become manifest in the upper urothelial tract, whereas its incidence increases continuously due to demographic change [
1]. The main aspect favoring radical surgery is that almost two-thirds of UTUC are detected in an invasive stage [
1]. Thus, NU currently represents standard care for the most cases of UTUC [
1]. Despite laparoscopic NU has been already introduced in 1991, many centers still perform open surgery, not least because of sophisticated utilization of laparoscopic instruments and a flat learning curve particularly for the bladder cuff [
2]. With a growing adoption of robot-assisted surgery, NU is nowadays increasingly performed using this platform. Several approaches for robot-assisted NU have been reported so far. The most common way to perform this surgery is currently transperitoneal approach, for which several port placements have been reported [
3‐
5]. In this context several colleagues [
6‐
8] demonstrated a feasible access to the upper abdomen (nephrectomy portion) and simultaneously to the lower abdomen (bladder cuff excision) using DaVinci
R robotic platform for a single-docking technique. While Patel and colleagues proposed their port placement in a straight line to the linea semilunaris lateral to the rectus abdominis muscle [
6] quite similar to Zargar et al. [
7], Darwiche et al. set up an oblique line for port placement beginning from subcostal space and ending near to linea alba in the lower abdomen [
8]. Importantly, transperitoneal approaches necessitate mobilization of the bowel by paracolic incision of the dorsal peritoneum to access retroperitoneal space. Based on the experience from robot-assisted partial nephrectomy a strictly retroperitoneal approach might in turn be beneficial for the control of hilar structures and reduction of intraoperative blood loss, operative time and hospital stay by decreasing postoperative discomfort especially triggered by pain and intestinal atony [
9‐
11]. Moreover, retroperitoneal approach might be preferential for patients with previous abdominal surgery to avoid intraperitoneal adhesions and occasionally time-consuming adhesiolysis [
9]. To date, a number of studies described retroperitoneal access for robot-assisted NU, but none of these surgeries were completed under robotic assistance [
4,
12,
13]. In the majority of cases management of the bladder cuff after robot-assisted retroperitoneal nephrectomy was only possible through intraoperative switch to either conventional laparoscopic surgery or even open surgery [
4,
12,
13].
We aimed at assessing our innovative surgical approach with a singular trocar placement for the first RRNU in which all surgical steps are completed using the DaVinciRXi robotic platform.
Discussion
To date there are no reports on a surgical technique allowing to perform all surgical steps of a robot-assisted NU using only retroperitoneal space. Due to our novel port configuration and ongoing improvements of robotic systems, we create and establish an approach of completely retroperitoneally executed NU with a bladder cuff resection. Notably, our innovative trocar placement integrates two well-established concepts: the robot-assisted retroperitoneal partial nephrectomy [
8] and the robot-assisted transperitoneal adrenalectomy [
16]. While creation of the retroperitoneal space is based on the principles of the retroperitoneal partial nephrectomy, the arrangements of the ports is adapted to that of the transperitoneal adrenalectomy with placement of trocars in a curved line parallel to the arcus costalis. Due to this modified port arrangement and after simplified re-docking, nephroureterectomy and dissection of the bladder cuff is both possible through the same ports and fully retroperitoneally.
The nephrectomy portion is thereby quite similar to that described by other groups utilizing retroperitoneal access for robot-assisted NU keeping in mind that none of these studies completed surgery under robotic assistance [
4,
12,
13]. Compared to the transperitoneal approach which is currently the most common technique, we observed similar surgical characteristics with our technique. Whereas Patel et al. demonstrated a mean surgery time of 152 min [
6] and Darwiche et al. of 184 min [
8], our operative time was as long as 189.2 min (median 170 min; IQR 165–181). As expected, trocar placement took longer with 28 min (median 24 min; IQR 22–35
) due to a more sophisticated creation procedure of the retroperitoneal space. Raheem et al. reported a docking time of 17.8 min using DaVinci
RXi for transperitoneal partial nephrectomy [
17]. Several surgical techniques reported the need of re-docking and relocation of the robot for management of the bladder cuff, what generally leads to an additional operative time of 30–60 min [
4]. Due to the possibility of a 180°-twist of the main robotic joint right after finishing nephrectomy portion without the need of relocation, this adds only a negligible additional time of 7 min for our RRNU.
Intra- and postoperative complications were rare. No conversion to open or laparoscopic surgery was observed. While we noted a median EBL of 150 ml (IQR 100–250), several studies described a comparable EBL of 120–200 ml [
6‐
8,
18]. Furthermore, we reported an intraoperative change of procedure in terms of switching from 0° to 30°camera for management of the bladder cuff (EAUiaiC grade 2 complication) what might be attributed to the previous radical prostatectomy in this patient. After switching to a 30°camera bladder cuff dissection was easily possible. In total, nephrectomy portion using four-arm configuration was feasible, while the three-arm configuration for the lower portion led sometimes to clashing of the instruments. Nevertheless, proper dissection of the bladder cuff was possible in all cases, what is of a great importance considering the high recurrence rate of up to 30–64% in cases with incomplete removal [
19]. Interestingly, Wu et al. just defined novel criteria for sufficient bladder cuff dissection including en-bloc excision, mucosa-to-mucosa reliable closure and no urine spillage [
20].
No major postoperative complications or readmissions after discharge were observed. Interestingly, hospital stay was 5.4 days (range 5–7) while other groups reported of 2–7 days (range 1–14) [
6‐
8,
18]. These varying data may be related to differences in health care systems and department policies impeding a reliable comparison [
21].
Attention should be paid here to the potential concern of heat conduction and burning of port site when inserting a standard 8-mm robotic trocar in the 12-mm Hasson trocar often raised by technical professionals and stakeholders. We usually apply this approach due to lower expenditures related to one-way Hasson trocar and retroperitoneal balloon. In the present series as well as in our retroperitoneal partial nephrectomy procedures, we have never encountered any adverse events related to the aforementioned issue. However, unless there is a reliable evidence for the same safety, Hasson cone of Intuitive Surgical appears to be a safer option and should be a preferable choice in the future.
Our successful implementation of RRNU is underpinned by histological and postoperative findings. All patients with UTUC showed no positive surgical margins even if mean tumor size was 3.02 cm. Studies including larger cohorts noted positive margins of 2–23% [
6,
7,
18,
22]. For closing the bladder defect, we performed a one-layer closing technique with a barbed suture and intraoperative watertightness testing by irrigating the catheter demonstrated no urine leakage in all cases. In addition, postoperative drain removal was performed between day 2–4 after excluding urine admixture in drain fluid and sufficient cystography demonstrated regular recovery of the bladder defect. Within a follow-up of 2–8 months no patient experienced systematic recurrence while one patient had multifocal localized bladder recurrence of a pTa urothelial carcinoma in the follow-up cystoscopy and a consecutive TUR-B, as is described for 22–47% of all patients with UTUC [
1].
Based on the findings from robot-assisted partial nephrectomy, a fully retroperitoneal as compared to a transperitoneal approach might be beneficial for certain aspects. While in some studies it was associated with a reduction in operation time [
10,
11,
23], intraoperative EBL [
11] and hospital stay [
9,
24], major intra- and postoperative complication rates were nearly the same [
25]. However minor complications (Clavien grade 1–2) seem to be even less frequent for patients undergoing a retroperitoneal approach [
25]. It is noteworthy that in general studies comparing postoperative patient reported outcomes particularly concerning pain and first bowel movement between retroperitoneal versus transperitoneal approach for kidney surgery are yet missing.
Our study has some limitations. We developed a new surgical technique based on observations of a single-center study while surgery was always carried out by the same operation team. In addition, we describe a small cohort and regarding to postoperative follow-up, especially referring to tumor specific long-term observations, we covered only a short period after surgery. Nevertheless, we believe to have created a feasible and generalizable surgical technique that should be compared to other techniques in prospective studies.
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