Benefits of transitioning from transperitoneal laparoscopic to retroperitoneoscopic adrenalectomy—a single center experience

Introduction

Minimal invasive surgery (MIS) has been proven to be advantageous for the postoperative course of patients, such as less postoperative pain, blood loss, faster return to daily life, shorter hospital stay and reduced mortality (1-3). MIS also gained popularity among endocrinological surgeons (4-7). Apart from the open approach, there are two minimal invasive procedure: the laparoscopic transperitoneal (LTA) and the retroperitoneoscopic adrenalectomy (RPA) (8-11). Since the introduction of these techniques in 1992 and 1993, both operative techniques have been established as safe procedures (12). Even though evidence supporting the superiority of one of these two operative techniques is lacking, opinions differ when choosing the better approach (17-20). Walz et al. have shown in various papers the many advantages of the RPA, such as less pain, less blood loss, shorter hospital stay and quicker return to daily life (1,13,14). Particularly in obese or previously operated patients, the RPA shows a clear superiority and therefore mastering this procedure can prove beneficial not only for patients, but also for the surgeon (15,22).

The objective of this retrospective study was to analyze the transition of LTA to RPA in a tertiary referral hospital center, especially emphasizing intra- and postoperative complications and visualizing the operative learning curve. We present this article in accordance with the STROBE reporting checklist (available at https://gs.amegroups.com/article/view/10.21037/gs-24-286/rc).

Methods

Patient collective

Consecutive patients (n=237) who received either a laparoscopic transabdominal (n=132) or retroperitoneoscopic (n=105) adrenalectomy at the Medical University of Vienna, Department of General Surgery, in the period between January 2012 and December 2020 were included in this retrospective study. Clinicopathological factors, intraoperative complications and conversions, postoperative outcomes, length of hospital stay and operative time were analyzed.

In 2017, the first RPA was performed at our department. All operations were performed by three experienced endocrine surgeons. Since 2017, RPA has been conducted in most cases, whereas the laparoscopic transabdominal adrenalectomy (LTA) has been performed in a small number of chosen cases.

Surgery

During the RPA procedure, the patient is placed prone in the jackknife position. Three trocars are placed below the lowest tip of the 12^th rib. The CO₂ insufflation can be set higher than at the LTA, with peaks reaching 20 mmHg.

During the LTA procedure, the patient is placed in a semilateral decubitus position and elevated at 60°. Four trocars are placed semicircular below the costal arch (16).

The operating time, defined as skin-to-skin time, was calculated separately for unilateral and bilateral adrenalectomies. To visualize the learning curve, the mean operative time (± standard deviation) was computed for each consecutive year. This approach was appropriate given the similar distribution of cases and surgeons during the first and second 2-year periods.

Information about tumor size has been collected from histological findings. When bilateral adrenalectomies were conducted, both tumor sizes have been used for calculations.

Postoperative data

Hospital stay was defined by day of admission until day of discharge.

Routine check-ups occur 2 weeks after discharge at the outpatient clinic of the department of general surgery, and then 6 weeks postoperatively at the department of endocrinology.

Statistical analysis

Continuous variables were presented as the mean values ± standard deviation. Statistical analysis was based on χ² test, t-test, Mann-Whitney U test and Pearson correlation, as appropriate. All statistical analyses were performed using SPSS Statistics ver. 22.0 (Vienna, Austria).

Ethical statement

The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). The study was approved by the Institutional Review Board of the Medical University of Vienna (No. EK 1170/2023). Informed consent was waived due to the retrospective nature of the study.

Results

Two hundred thirty-seven patients underwent 211 unilateral and 26 bilateral adrenalectomies at our department from January 2012 until end of December 2020. 60.8% (n=144) patients were female, and 39.2% (n=93) were male. Median age was 53 years. Tumor size ranged from 3 to 150 mm.

Hundred and five patients received an RPA, of whom 60 (57.1%) were female, 45 male (42.9%). The mean age in this group was 54.54±2.65 years and mean body mass index (BMI) 27.76±1.16 kg/m². Ten patients underwent a bilateral adrenalectomy, left side was more common (n=57) as the right side (n=38). The mean tumor size was 30.98±3.77 mm, ranging from 3 to 92 mm.

One hundred thirty-two patients underwent a laparoscopic transperitoneal adrenalectomy (LTA), in this patient collective 84 patients were female (63.2%) and 48 male (36.8%). The mean age was 52.54±2.34 years, mean BMI 26.82±0.84 kg/m². Fifty-four adrenal tumors were located on the right side, 62 on the left. Sixteen bilateral operations took place (Table 1).

Diagnoses and histological findings

The most common diagnoses were pheochromocytoma (n=64), hyperaldosteronism (n=36), Cushing syndrome (n=49), incidentaloma (n=44), metastasis (n=11) and other (n=33).

Histopathological findings were evaluated in both groups, separately: in the RPA collective the most common findings were adrenal cortical adenoma (n=56), pheochromocytoma (n=25), adrenal cortical hyperplasia (n=7) and adrenal cortical cancer (n=2). In the LTA group the most findings were adrenal cortical adenoma (n=57), pheochromocytoma (n=39), adrenal cortical hyperplasia (n=11) and adrenal cortical cancer (n=6) (Table 2).

Complications

In total, conversion rate was 5.49% (13 patients). In the RPA group 4 patients needed conversion to median laparotomy (3.8%) due to bleeding (n=3) and adhesions (n=1). In one case the injury of the kidney artery led to uncontrollable bleeding and then to the nephrectomy. In another case during dissection due to adhesions to the parenchyma of the spleen led to an unstoppable bleeding and a splenectomy had to be performed. The conversion rate in the LTA group was 6.82%. The nine conversions were caused by bleeding (n=2), adhesions (n=1), difficult access (n=1) and unclear anatomy (n=1). Four planned conversions (n=4) were conducted: in two cases in order to avoid tumor rupture, one case received simultaneously surgical treatment for the abdominal aortic aneurysm and one patient had an infiltrating tumor into the renal vein. One intraoperative complication occurred in the LTA group due to uncontrollable bleeding from the spleen after dissection, but was managed laparoscopically with no necessary conversion (Table 3).

In usage of Z-score, no correlation could be found between operative technique and conversion rate (P=0.42).

Postoperative complications were documented in both groups: in the RPA group, 4 patients had minor wound infections (3.81%), whereas in the LTA group, a variety of complications occurred (3.4%): pneumonia (n=1), urinary tract infection (n=1), and one case of significant blood loss (n=1) due to kidney artery injury on the second postoperative day with need for revisional surgery (Table 4).

Operating time—learning curve

The median operating time significantly differed in the groups (P<0.001): 50 min in the RPA and 125 min in the LTA group. In both groups, the operating time was higher for patients receiving a bilateral adrenalectomy.

The operating time gradually decreased throughout the years after starting with the RPA technique (rank correlation, P=0.051), clearly showing the operative learning curve of the two performing endocrine surgeons. In the first year of establishing this new procedure the median operating time was at 60 min, declining each year and at the end of the study period, an adrenalectomy was performed in less than 45 min (Table 5). The significant decline in surgery time is visualized in Figure 1.

Figure 1 Operating time in RPA group divided into each year including unilateral and bilateral adrenalectomies. RPA, posterior retroperitoneoscopic adrenalectomy,

No capsule ruptures were documented in both groups. Patients with carcinomas received R0 resection. Tumor size was significantly smaller in the RPA group. There was no mortality in both groups.

Hospital stay

The median hospital stay was 3 days in the RPA group, there was a significant difference (P=0.01) when comparing the hospital stay between the unilateral and bilateral adrenalectomy groups: mean stay of 3.63 and 8.8 days. In the LTA group the median hospital stay was 9 days, significant variation in the unilateral and bilateral group: 8.84 and 14.38 days (Table 6).

Discussion

In 1992, Higashihara and Gagner both reported a new way to perform an adrenalectomy: the LTA as a new MIS technique (17,18). This utterly changed the field of endocrine surgery and superseded the open surgery approach entirely after a few years. Shortly after these publications, Brunt et al. experimented with a retroperitoneoscopic approach in a swine model, followed by first case reports in patients (19-22). In 1995, Walz et al. published an improved technique of the RPA in a prone jack-knife position (23,24).

Overall, the goal of MIS is less postoperative complications, shorter hospital stay and faster return to daily life. Due to this fact, the indication for MIS (especially LTA and RPA) in endocrine surgery has been expanded with the improvement of surgical techniques and operative instruments. Conzo et al. emphasize that technological advancements in surgical tools and techniques account for reduced operative times and extended indications for treating more complex patients (15). Various studies have shown that both minimal invasive techniques are safe, feasible and have many advantages concerning the postoperative outcome (12,25,26).

Even though evidence supporting the superiority of one of these two operative techniques is lacking, opinions differ when choosing the better approach (17-20). Studies report similar results concerning morbidity and mortality (27-29). The gold standard for most adrenal tumors has been the LTA, since it has been proven to be a safe procedure with minimal complication and conversion rates (21). This is one of the reasons why most surgeons perform the LTA, other reasons are more experience with laparoscopy, knowledge of transabdominal anatomy and available landmarks (30).

The adrenalectomy through the retroperitoneoscopic approach has gained popularity due to its many advantages: direct access with minimal dissection, usage of more pressure, leaving peritoneal cavity intact and shorter operative and recovery time (8,16,19,26,31).

No mobilization of peritoneal organs needs to be conducted, hence risk of organ injury decreases (32). Avoiding the opening of the abdominal cavity will be crucial in the future, since the “normal” patient is overweight or obese with rising tendencies, nowadays. This changes the intraoperative setting, exceedingly in male patients, who generally have more visceral fat tissue. Thus, making the RPA the clear choice (32). One disadvantage needs mentioning: the small working space during the RPA might make surgery more difficult, hence the cut-off of removing an adrenal tumor is 6 cm for minimal invasive techniques in general (4,33).

Various studies show a slight benefit for the RPA: Heger et al. reviewed in 2017 the different operating approaches and were able to demonstrate not only a better outcome for minimal invasive procedures, but also slightly better results for RPA concerning length of hospital stay and operative time (34). Bonjer et al. evaluated the effectiveness of the RPA in more than 100 patients, coming to the conclusion that it is a safe and feasible procedure to be used for tumors with sizes until 6 cm in diameter, in accordance with the guidelines of the German Association of Endocrine Surgeons (CAEK) (8,35). We are able to report similar results in our study collective, with significant shorter operative time and hospital stay, without increasing postoperative complications. Yet, the RPA has not become the gold standard for adrenalectomies, due to the fact that this procedure takes place in an unfamiliar operative field, needs a high-volume center to gain experience in order to flatten the learning curve, and is not advised for larger tumors so far.

When establishing a new operative technique, there is a needed number of cases to fulfill the operative learning curve. Walz et al. have shown a number of 30 to 40 RPAs to gain the needed experience to perform this technique safely (13,14). Vrielink et al. report slightly fewer numbers with around 24 and 42 procedures, with a 5% conversion and 18.8% postoperative complication rate (36). Van Uitert et al. describe that 40 procedure are necessary for the learning curve, with less than 2% conversion rate and similar postoperative complications as in the LTA group (4). In this study, there was a significance difference in the operative time in the RPA and LTA group. RPA is beneficial in bilateral adrenalectomies since no repositioning is necessary. A flattening of the operative learning curve could be clearly seen in the RPA group since establishing this new operative technique in 2017. This flattening shows after a year of operations, which entails 33 cases matching the above-mentioned studies. While the literature describes conversion rates from 2–14% for patients undergoing RPA, this study reports conversion rate of 5.49% and the postoperative complications rate at 4%, respectively (12). Conversion occurred in the RPA group due to adhesions or bleeding, which in one case led to the nephrectomy. However, in the LTA group twice as many conversions and more severe postoperative complications could be found. Nevertheless, no significant difference could be shown. All patients were converted to an open method and recovered well postoperatively. Both operative techniques show similar outcomes and have to be chosen in accordance with the local infrastructure and the personal preference of the treating surgeon. The best postoperative outcomes after adrenalectomies have been shown to be dependent on high-volume surgeons, regardless of pathology (22). The number of performed adrenalectomies per year in order to be a high-volume surgeon differ (37).

In this retrospective study, we demonstrated significantly shorter operative times in the RPA group, with comparable conversion and complication rates. The study also highlights the short learning curve for RPA, with operative times decreasing from 60 min in the first year to under 45 min by the end of the study period.

Limitations

To the character of this retrospective study, there are some limitations that need mentioning. The longest hospital stay has been documented in the LTA in the first years of this study with a median stay of 9 days. This is due to the fact, that patients used to get admitted to the inpatient ward for preoperative check-ups and observance, especially while undergoing alpha-blockade for pheochromocytoma, as well as longer postoperative care prior discharge: at the beginning of the observation period, patients suffering from pheochromocytomas were admitted to the intensive care unit (ICU) postoperatively for observation, and readmitted to the ward after one day. Due to the novelty of the RPA technique in our clinic, there is a selection bias: patients with smaller tumors and lower BMI were initially chosen to undergo this new procedure. In the future, single-blind studies and randomized controlled trial (RCTs) can reduce selection bias and other limitations.

Conclusions

RPA is a safe and feasible surgical technique, which offers advantages and should be performed, when certain expertise is given. The operative learning curve can be achieved early without higher complications but careful patient selection is essential initially. On the basis of these experience, a transition from transperitoneal laparoscopic to RPA can prove beneficial in specialized centers.

Acknowledgments

Funding: None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://gs.amegroups.com/article/view/10.21037/gs-24-286/rc

Data Sharing Statement: Available at https://gs.amegroups.com/article/view/10.21037/gs-24-286/dss

Peer Review File: Available at https://gs.amegroups.com/article/view/10.21037/gs-24-286/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://gs.amegroups.com/article/view/10.21037/gs-24-286/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). The study was approved by the Institutional Review Board of the Medical University of Vienna (No. EK 1170/2023). Informed consent was waived due to the retrospective nature of the study.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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