Retroperitoneal Robotic-Assisted Laparoscopic Pyeloplasty: A 10 Year Experience in a Single Institution

Abstract

Introduction:

Pelvi-ureteric junction (PUJ) obstruction was traditionally treated with open pyeloplasty. In recent decades, the development of minimally invasive techniques, including laparoscopic and later robotic surgery, has transformed treatment. The transperitoneal approach has most commonly been undertaken, with a few institutions reporting outcomes of the retroperitoneal approach. We report our 10-year experience of retroperitoneal robotic-assisted laparoscopic pyeloplasty (R-RALP).

Methods:

A prospective database of 160 patients undergoing RALP between February 2010 and November 2019 was analyzed. Data were recorded on demographics, operative details, complications, and success rate. Success was determined as symptomatic improvement and/or an unobstructed renogram.

Results:

One hundred fifty-two cases (95.0%) were performed by using a retroperitoneal approach, and 8 (5.0%) were performed by using a transperitoneal approach. Mean age was 45.3 ± 17.4 years. Mean operating time was 139.4 ± 45.6 minutes. A surgical drain was placed in 57 (71.3%) of the first 80 cases and 15 (18.8%) of the second 80 cases. Median hospital stay was one night (range 1–27). One case was converted to open pyeloplasty due to dense inflammatory tissue and one to robotic-assisted nephrectomy due to severe adhesions around the PUJ. There were no blood transfusions. There were six major (>grade 2 Clavien–Dindo) postoperative complications in four patients (2.5%). Two (1.3%) grade 3a complications, urine leak and pain after stent removal, required nephrostomy. There were three (1.9%) grade 3b complications: migrated stent requiring ureteroscopy, perirenal hematoma requiring open evacuation, and stent re-insertion. One (0.6%) grade 4 complication required ventilatory support on intensive care. Eighteen patients received follow-up at an alternative hospital, and 13 were lost to follow-up. Of the remaining cases, 94.5% were successful.

Conclusions:

R-RALP is a safe and effective treatment for PUJ obstruction allowing predictably rapid discharge from hospital without the need for a routine surgical drain. To our knowledge, our study represents the largest single institution experience on RALP using a retroperitoneal approach.

Introduction

Open pyeloplasty was the historical gold standard treatment of choice for more than 100 years for pelvi-ureteric junction (PUJ) obstruction.¹ In recent years, minimally invasive approaches for pyeloplasty have emerged: The first laparoscopic pyeloplasty was described in 1993, and the first robotic pyeloplasty was described in 2002.^2,3 Both of these minimally invasive approaches have demonstrated success rates comparable to that of open surgery, with benefits of improved pain control and a quicker recovery.^4,5 In addition, robotic-assisted laparoscopic pyeloplasty (RALP) has been demonstrated to have quicker operating times over laparoscopic pyeloplasty.⁶

RALP can be performed by using either a transperitoneal or retroperitoneal approach. A transperitoneal approach provides familiar anatomical landmarks and sufficient working space. This may be the reason for its apparent preference, with the majority of cases reported in the literature.⁵ Conversely, the retroperitoneal approach requires working in a smaller space with a scarcity of landmarks. However, unlike the transperitoneal approach, mobilization of the colon is not required and it allows quick access to the PUJ. Having performed laparoscopic pyeloplasty through this route before the arrival of the robotic platform, we moved to reproducing the same procedure but robotically assisted for the past 10 years. The aim of this case series is to report our experience and outcomes of retroperitoneal-RALP (R-RALP).

Methods

Between February 2010 and November 2019, 160 consecutive patients presenting with PUJ obstruction underwent RALP in a single institution. The retroperitoneal approach was predominantly used. The transperitoneal approach was only performed in cases where the renal pelvis itself was not particularly dilated, introducing concerns about achieving a secure and tension-free anastomosis in a fully flexed patient. The procedures were performed by three consultant urologists who were experienced in minimally invasive surgery at the start of the study, and five supervised trainees. Diagnosis was made on clinical assessment, CT with or without retrograde ureteropyelography, and mercaptoacetyltriglycine (MAG)-3 renogram.

Operative technique

All procedures are performed under a general anesthetic, with antibiotic prophylaxis delivered on induction. A cystoscopy and retrograde ureteropyelogram are performed. A retrograde Double-J stent is inserted at the start of the procedure, and a urethral urinary catheter is placed. The patient is placed in the modified flank position. The operating table is fully flexed to increase the space between the iliac crest and 12th rib. A 12 mm incision is made 5 cm (two fingerbreadths) above the iliac crest in the mid-axillary line.

A 12 mm PDB™ Auto Suture™ Round Shape Balloon (Covidien™, Mansfield, MA) is inserted and inflated to create the retroperitoneal space. The dilator device is exchanged for a 12 mm Kii^® Balloon Blunt Tip System (Applied Medical, Rancho Santa Margarita, CA). An 8 mm da Vinci^® S port is inserted in the superior lumbar (Grynfeltt-Lesshaft) triangle under direct vision. Another 8 mm da Vinci S port is placed 10 cm from the camera port in the anterior axillary line cephalad to the anterior superior iliac spine. A 12 mm Airseal Access port (SurgiQuest, Milford, CT) is placed midway between the camera port and the most medial robotic port.

The da Vinci Si HD Surgical system is positioned in front and toward the head of the patient. The stented ureter is identified, mobilized, and dissected toward the renal pelvis. The lower pole of the kidney is occasionally mobilized. The ureter is opened, the PUJ excised, and the pelvis and proximal ureter spatulated. In cases of a crossing vessel, the PUJ is usually simply divided, the pelvis and ureter again spatulated and transposed anterior to the crossing/accessory vessel(s). An interrupted 4/0 Vicryl anastomosis is performed over the stent. Overtime and with more experience, it has become routine not to leave a postoperative surgical drain unless there are concerns regarding the integrity of the anastomosis.

The ureteric stent is removed 4 weeks postoperatively at flexible cystoscopy under local anesthesia. The patient is reviewed at 3 and 12 months with a MAG-3 renogram and symptoms are assessed. In cases where there were ongoing symptoms or evidence of obstruction on the MAG-3, the patients continued with follow-up as was deemed necessary. Treatment success was determined as symptomatic improvement (based on patient reporting) and/or an unobstructed or improvement in drainage on renogram. In patients who had a persistently obstructed renogram, the procedure was deemed successful if the patients' symptoms improved.

Data collection and analysis

Data were prospectively collected on patient demographics, operative details, complications, and success rate. Results for parametric data are reported as mean ± standard deviation (range) and for nonparametric data as median (range).

Results

Patient characteristics and presenting symptoms of the 160 patients undergoing RALP are shown in Table 1. Mean patient age was 45.3 years. Seventy-four (46.3%) patients were male. Mean body mass index was 25.8 kg/m². Median ASA grade was 1. There was one (0.6%) patient with a single kidney, one (0.6%) patient with a horseshoe kidney, and three (1.9%) patients with bilateral PUJ obstruction. In 25 (15.6%) cases, whether the patient had symptoms was not recorded. In the remaining 135 patients, the most common presenting symptom was pain affecting 90 (66.7%) patients. In 21 (15.6%) patients, PUJ obstruction was an incidental finding on imaging.

Table 1.

Patient Characteristics and Presenting Symptoms

Patient characteristics
Mean age (years)	45.3 ± 17.4 (17–2)
Male, n (%)	74 (46.3)
Mean BMI (kg/m²)	25.8 ± 5.6 (16.9–43.1)
Median ASA	1 (1–3)
Single kidney, n (%)	1 (0.6)
Horseshoe kidney, n (%)	1 (0.6)
Bilateral PUJ obstruction, n (%)	3 (1.9)
Presenting symptoms (n = 135)	n (%)
Pain	90 (66.7)
Asymptomatic (incidental)	21 (15.6)
Infection	24 (17.8)
Symptomatic (symptoms unknown)	8 (5.9)
Hematuria	1 (0.7)
Recurrent kidney stones	1 (0.7)

BMI = body mass index; PUJ = pelvi-ureteric junction.

Table 2 shows the operative details. Ninety-five percent of the cases were performed by using a retroperitoneal approach. Mean operating time was 139.4 ± 45.6 (60–330) minutes. One hundred (62.5%) patients were found to have a crossing or accessory vessel(s). Mean estimated blood loss was 10.0 mL. In 72 cases (45.0%), a surgical drain was placed for a median duration of 1 day. In the first 80 cases, 71.3% patients had a drain left in situ compared with 18.8% in the last 80 cases. Median hospital stay was one night.

Table 2.

Operative Details for Patients Undergoing Robotic-Assisted Laparoscopic Pyeloplasty

Operative details
Retroperitoneal, n (%)	152 (95.0)
Transperitoneal, n (%)	8 (5.0)
Right side, n (%)	82 (51.3)
Left side, n (%)	78 (48.8)
Mean operating time (minutes)	139.4 ± 45.6 (60–330)
Crossing vessel, n (%)	100 (62.5)
Mean estimated blood loss (mL)	10.0 ± 26.8 (0–200)
Surgical drain, n (%)	72 (45.0)
Median drain duration (days)	1 (1–5)
Median hospital stay (days)	1 (1–27)

One (0.6%) case was converted to open pyeloplasty due to dense inflammatory tissue. In 1 (0.6%) other case, pyeloplasty was abandoned and robotic-assisted nephrectomy was performed due to severe adhesions around the ureter and PUJ. In 1 (0.6%) case, unexpected urothelial carcinoma was found at the PUJ despite a normal contrast enhanced CT scan of the urinary tract and normal retrograde uretropyelogram study.

Nine (5.6%) patients experienced 11 complications (Table 3). There were 2 (1.3%) Clavien–Dindo grade 1 complications: persistent urinary leakage managed conservatively with the surgical drain and a pneumothorax that was managed conservatively. There were 3 (1.9%) Clavien grade 2 complications, and all infections were treated with antibiotics. One (0.6%) patient experienced three complications greater than Clavien grade 2. This patient was admitted to intensive care for respiratory support postoperatively (Clavien 4).

Table 3.

Postoperative Complications Listed According to the Clavien–Dindo Classification System

Postoperative complications	n (%)
Clavien–Dindo grade 1
Persistent urinary leakage	1 (0.6)
Pneumothorax	1 (0.6)
Clavien–Dindo grade 2
Urinary tract infection	2 (1.3)
Wound infection	1 (0.6)
Clavien–Dindo grade 3a
Nephrostomy	2 (1.3)
Clavien–Dindo grade 3b
Migrated ureteric stent—ureteroscopy	1 (0.6)
Open evacuation of perirenal hematoma	1 (0.6)
Ureteric stent re-insertion	1 (0.6)
Clavien–Dindo grade 4
Intensive care admission	1 (0.6)

The same patient returned to the theater, had an open evacuation of a peri-renal hematoma (Clavien 3b), and later went on to have a urine leak requiring a nephrostomy (Clavien 3a). The second patient who required a nephrostomy required it due to pain from restenosis after stent removal. The two additional Clavien 3b complications were a migrated ureteric stent requiring ureteroscopy and stent retrieval and a patient who required ureteric stent re-insertion for obstruction after the initial stent was removed. No patients required a blood transfusion.

Follow-up data were available for 128 (80.5%) patients. In these 128 patients, the median length of follow-up was 12 months (3–36 months) and 121 patients (94.5%) had a successful outcome. In the 7 (5.5%) patients where RALP was unsuccessful, 3 (2.3%) went on to have balloon dilatation, 2 (1.6%) had a re-do pyeloplasty, 1 (0.8%) patient was managed with a long-term ureteric stent, and 1 (0.8%) is awaiting further treatment. The 31 (19.5%) patients without follow-up data include 18 (11.3%) patients who received follow-up at an alternative hospital and 13 (8.2%) patients who were lost to follow-up.

Discussion

We report our experience of performing RALP over a 10 year period in an adult population using a predominant retroperitoneal approach. Much of the reported literature focuses on the pediatric population, with a few reported series in adults and many of these are of a small size. To our knowledge, there is only one reported series with a larger volume of patients that was conducted across 15 institutions and included 465 patients undergoing RALP.⁷ However, this study did not report whether a transperitoneal or retroperitoneal approach was used. Our study, therefore, represents the largest reported single institution experience and the largest series of R-RALP.

The approach to RALP is important to facilitate successful reconstruction without adding technical difficulties. This choice is typically down to surgeon preference largely based on their previous experience. The retroperitoneal approach allows quick access to the PUJ without the need to mobilize the colon, which reduces the risk of any potential bowel injury as demonstrated in our series where there were none. There are also no reports of bowel injury in the limited number of other reported R-RALP case series.^8
–10

Comparatively, there are reports of colonic injury during RALP using a transperitoneal approach.¹¹ Further, data from laparoscopic surgery, of which there are more reported series, place the incidence of bowel injury during transperitoneal urological surgery as high as 0.9%.¹² Although it is rare, bowel injury is a serious potentially life-threatening complication that can be avoided by using a retroperitoneal approach.

Mean operating time in our study was 138.4 minutes (including the retrograde siting of a ureteric stent), which is comparable to other case series reporting a retroperitoneal approach where the mean ranged from 118 to 175 minutes.^8
–10 In large transperitoneal case series (>50 transperitoneal RALP in adults), the reported mean operating time ranges from 108 to 217 minutes.^11,13

–16 However, in one outlying study, the mean operating time was reported to be as high as 335 minutes.¹⁷ The variability in operating times across studies is likely due to how it is defined as well as the surgeon's experience; there is no evidence to suggest that a retroperitoneal or transperitoneal approach significantly impacts this.

We have reported a success rate of 94.5%, which is comparable to other R-RALP series reporting success rates between 94.4% and 100%.^8
–10 However, it should be noted that these other studies are significantly smaller sample sizes of 10, 36, and 40 patients. The success rates in large transperitoneal case series show a lot more variability with rates between 81% and 97%.^{11,13

–17} However, given that there are significantly more transperitoneal case series available for comparison, it is not possible to suggest there is any benefit to success rate using a retroperitoneal approach. There are also likely to be a number of additional factors that influence success rate, including the surgeon's experience, underlying pathology, and chronicity of the obstruction.

A recent meta-analysis comparing retroperitoneal and transperitoneal approaches in both laparoscopic and RALP for the treatment of PUJ obstruction found no significant difference in success rates, complications, operating time, estimated blood loss, length of stay, or analgesia requirements.¹⁸ However, the analysis found a higher conversion rate for retroperitoneal cases. The authors have not found this to be the case in our series where there were no intraoperative conversions to a transperitoneal approach.

It is possible that this finding in the meta-analysis may, in part, be due to the surgeon's prior experience and lack of familiarity with the retroperitoneal approach. Further, the meta-analysis highlighted the benefit of the retroperitoneal approach with a quicker return to a regular diet by avoiding contact with intraperitoneal organs and a shorter drain duration.¹⁸

Unlike other reported large case series (>50 cases) of RALP, we no longer routinely leave a surgical drain at the end of the procedure.^10,14,15 In the early part of our series, drains were commonly left in situ (71.3% in the first 80 cases). With increasing experience, we identified that a drain was rarely required as when using a retroperitoneal approach there is no potential for intraperitoneal contamination. Therefore, in the second half of our series, only 18.8% of cases had a drain placed. The absence of a drain was not associated with any adverse events, demonstrating that RALP can be safely performed without leaving a drain.

The main strengths of our study lie in its prospective design, ensuring we have captured all patients at our institution undergoing RALP, and the high volume of cases. However, there are some limitations to our study. Our institution receives tertiary referrals to perform RALP and these patients often continue with follow-up in their local hospital, which leads to incomplete follow-up data in our study. Despite this, follow-up data were still available in more than 75% of cases and we can therefore be confident with our outcomes. In addition, patients having follow-up in local hospitals would most likely be referred back should their procedure fail or they develop complications. Further, as we predominantly use a retroperitoneal approach, there were very few cases of a transperitoneal RALP in our series. Therefore, no direct meaningful comparison between the approaches could be performed in our study.

Conclusion

R-RALP is a safe and effective treatment for PUJ obstruction and can be employed as the default approach in treating PUJ obstruction. The retroperitoneal approach achieves success rates comparable to the transperitoneal approach with no impact on the operative parameters, a short hospital stay and can safely be performed without the need for a routine surgical drain. To our knowledge, this study represents the largest single institution experience on RALP using a retroperitoneal approach.

Footnotes

Authors' Contributions

All authors have sufficiently contributed toward meeting the authorship criteria.

Author Disclosure Statement

No competing financial interests exist.

Funding Information

No funding was received for this article.

Abbreviations Used

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