Introduction
Robotic partial nephrectomy (RPN) has become an established surgical management of small renal masses [
1]. It offers minimally invasive access as laparoscopy, but a much easier learning curve [
2,
3]. RPN can be carried out via a transperitoneal or retroperitoneal approach. The choice between the two laparoscopic approaches is usually based on surgeon preference.
The transperitoneal approach has known broader diffusion due to the larger working space allowed and the supposed better recognition of anatomical structures.
On the other hand, the retroperitoneal approach would have the ideal advantage of avoiding the peritoneal cavity and, thus, the potential adhesions from previous transabdominal surgeries. Hypothetically, it gives easier access to posterior tumors. Moreover, the retroperitoneal approach grants direct access to the hilar structures without any kidney mobilization. Nevertheless, the confined space and the less familiar landmarks have limited the popularity of retroperitoneal approach across the urological community [
4].
The meta-analyses of literature published on the topic all go in the same direction, suggesting that the retroperitoneal approach may provide advantages in terms of shorter operative time, lower blood loss, and less perioperative morbidity [
4‐
6].
Unfortunately, most of the available studies lack patient-centered data about mobilization, canalization, postoperative pain, and the use of painkillers [
4].
The present analysis aimed to explore and compare transperitoneal and retroperitoneal approaches to RPN, focusing on such outcomes.
Discussion
The present study compared the transperitoneal versus the retroperitoneal approach to RPN, confirming a substantial similarity between the two laparoscopic routes except for blood loss, which favored retroperitoneoscopic RPN. The specific purpose of the study was to focus on patient-centered outcomes, which included postoperative mobilization with ambulation, return to complete bowel function, postoperative pain, and its management with painkillers. No differences were found in terms of these outcomes, except for painkiller consumption.
The simple comparison between transperitoneal and retroperitoneal laparoscopic surgical access to RPN is not inherently original. Consequently, numerous comparative studies have been published since the advent of robotic platforms, starting in 2013 [
16,
17]. Within the last decade, several research groups have summarized the available evidence in the field by publishing literature meta-analyses. Almost all the published studies have consistently reported certain advantages in terms of perioperative outcomes when a retroperitoneal approach is adopted. These include faster surgery, minimized blood loss, and shortened duration of hospitalization [
4‐
6].
The sole statistically significant difference identified in terms of perioperative outcomes in the context of the present study has been the lower blood loss observed in the retroperitoneoscopic cohort (median 150 (IQR 100–300) versus 100 (IQR 0–100) ml, transperitoneal versus retroperitoneal approach, respectively,
p = 0.03), consistent with previous experiences. Some authors have attributed the difference in blood loss to the requirement for a lesser extent of tissue dissection during retroperitoneal access [
18].
Nevertheless, the clinical impact of these differences appears to be negligible, as both techniques demonstrate comparable oncological efficacy and renal functional outcomes—the primary endpoints of partial nephrectomy.
Regrettably, the primary limitation of the existing literature lies in the predominance of either retrospective or prospective non-randomized designs in published studies. However, it’s worth noting that despite this limitation, some studies exhibit good quality by incorporating controls for potential confounders (i.e., a matched-paired analysis).
Furthermore, nearly all the published studies lack a prospectively detailed collection of what the authors consider more interesting outcome measurements. This is particularly notable when comparing interventions that involve the same surgical steps but are conducted through different laparoscopic accesses.
The most up-to-date and largest cumulative analysis of comparative studies about transperitoneal versus retroperitoneal RPN pointed out that “
the impact on quality of life indices remains to be determined” [
4]. What are we talking about? To the best of our knowledge, only a propensity score-matched analysis born within the RECORd 2 project (comparing > 400 patients per treatment group) reported data about bowel canalization and found a shorter time of return to bowel function with retroperitoneal access (median 3 (IQR 2–5) versus 2 (IQR 1–3) days, transperitoneal versus retroperitoneal, respectively,
p < 0.0001 [
19]. The finding is not unexpected. As such, during the retroperitoneal approach to nephron-sparing surgery, the bowel remains untouched, whereas the transperitoneal approach necessitates some degree of colonic dissection, carrying the potential for postoperative ileus.
Our database has the strength of a prospective data collection of specific postoperative outcomes which have remained anecdotally reported by previous literature about the topic, namely, beyond the just mentioned return to bowel function, the patient mobilization with ambulation after surgery, the perceived pain, and its management with painkillers.
The null hypothesis of our analysis posited that, due to its more targeted anatomical approach, the retroperitoneal method could minimize the impact of surgery, potentially resulting in lower pain, faster mobilization, and a quicker return to bowel function. However, our results did not support the null hypothesis, as the two approaches were comparable in these outcome measurements as well. It’s worth noting that our dataset included the Barthel index, collected preoperatively, indicating that all patients considered in our analysis had a comparable ability to perform activities of daily living before the surgery. Nevertheless, we observed a significantly higher adoption of painkillers for patients who underwent surgery via a transperitoneal approach. Although this finding contradicts the pain perceived, as assessed by the VAS in the present study, the increased consumption of painkillers could suggest the potential for lower invasiveness associated with the retroperitoneal approach. While the VAS is widely used and has been shown to be reliable and valid for pain assessment, no single tool is perfect for all situations. Pain is a complex and subjective experience, and different individuals may interpret and express their pain differently. In some cases, the combination of pain assessment tools should be preferred to gather a more comprehensive understanding of the pain experience.
We acknowledge the limitations of our study. First, although the prospective granular data collection, the study design was retrospective, which led to potential imbalances between the cohorts despite propensity score matching: this is not always the ideal approach for establishing causal inference, as it does not account for unobserved confounders. This may explain why we failed at finding any significant difference between the two approaches. Second, the study was conducted in the setting of a tertiary referral institution for nephron-sparing surgery. This could limit the generalizability of our findings. But, while most centers have limited/no expertise with the retroperitoneal route (we believe this could compromise a fair comparison between the two techniques), we pride ourselves on extensive experience with both the approaches. We feel this is another strength of the present analysis.
On the other hand, it is interesting to note how surgeons performing single-port RPN in the United States by using a novel purpose-built robot are more likely to choose a retroperitoneal approach. This is likely due to one of the key features of the “SP” robot, which is well suited to work within narrow spaces such as the retroperitoneum, facilitates access and docking, and reduces the need for dissecting several anatomical structures before performing the resection of the renal mass [
20]. Thus, the advent of single-port robotic surgery in Europe could expand the interest towards retroperitoneal access for RPN [
21].
Finally, to the best of our knowledge, this is the first study investigating some unconventional quality of life-related outcome measurements, relying upon a decent sample size relative to the topic investigated. We sincerely believe this is a plus of our effort which adds to previous literature.
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