Laparoscopic parenchymal sparing resections in segment 8: techniques for a demanding and infrequent procedure

A safe and simple exposure and Pringle maneuver in laparoscopic anatomical liver resection of segment 7

BACKGROUND

Laparoscopic access to liver segment 7 (S7) is difficult for deep surgical situations and bleeding control. Herein, our proposed laparoscopic technique for S7 lesions using a self-designed tube method is introduced.

METHODS

Clinical data of patients who underwent laparoscopic anatomical liver resection of S7 (LALR-S7) with the help of our self-designed tube to improve the exposure of S7 and bleeding control in the Second Affiliated Hospital, Third Military Medical University (Army Medical University) from April 2019 to December 2021 were retrospectively analyzed to evaluate feasibility and safety.

RESULTS

Nineteen patients were retrospectively reviewed. The mean age was 51.3 ± 10.3 years; mean operation time, 194.5 ± 22.7 min; median blood loss, 160.0 ml (150.0-205.0 ml); and median length of hospital stay, 8.0 days (7.0-9.0 days). There was no case conversion to open surgery. Postoperative pathology revealed all cases of hepatocellular carcinoma (HCC). Free surgical margins were achieved in all patients. No major postoperative complications were observed. Patients with postoperative complications recovered after conservative treatment. During outpatient follow-up examination, no other abnormality was presented. All patients survived without tumor recurrence.

CONCLUSIONS

The preliminary clinical effect of our method was safe, reproducible and effective for LALR-S7. Further research is needed due to some limitations of this study.

All the Routes for Laparoscopic Liver Segment VIII Resection: A Comprehensive Review of Surgical Techniques

Liver surgery is highly demanding for anatomical, physiological and technical reasons, and minimally invasive approaches have been implemented at a slower rate. Today, laparoscopic liver resection is a standard of care in many occasions, yet specific operations remain particularly challenging and generally performed in open surgery. In particular, SVIII resection may be considered one of the most difficult due to anatomical characteristics including its sub-diaphragmatic position, the deep-lying Glissonean pedicle and the close contact with the inferior vena cava and right and middle hepatic veins. Many techniques have risen to overcome technical difficulties, and today laparoscopic SVIII resection has been demonstrated to be feasible. This review provides a complete picture of current approaches, focusing on all techniques reported so far with critical appraisal of each, discussing and explaining benefits and pitfalls.

Laparoscopic versus open resections in the posterosuperior liver segments within an enhanced recovery programme (ORANGE Segments): study protocol for a multicentre randomised controlled trial

BACKGROUND

A shift towards parenchymal-sparing liver resections in open and laparoscopic surgery emerged in the last few years. Laparoscopic liver resection is technically feasible and safe, and consensus guidelines acknowledge the laparoscopic approach in the posterosuperior segments. Lesions situated in these segments are considered the most challenging for the laparoscopic approach. The aim of this trial is to compare the postoperative time to functional recovery, complications, oncological safety, quality of life, survival and costs after laparoscopic versus open parenchymal-sparing liver resections in the posterosuperior liver segments within an enhanced recovery setting.

METHODS

The ORANGE Segments trial is an international multicentre randomised controlled superiority trial conducted in centres experienced in laparoscopic liver resection. Eligible patients for minor resections in the posterosuperior segments will be randomised in a 1:1 ratio to undergo laparoscopic or open resections in an enhanced recovery setting. Patients and ward personnel are blinded to the treatment allocation until postoperative day 4 using a large abdominal dressing. The primary endpoint is time to functional recovery. Secondary endpoints include intraoperative outcomes, length of stay, resection margin, postoperative complications, 90-day mortality, time to adjuvant chemotherapy initiation, quality of life and overall survival. Laparoscopic liver surgery of the posterosuperior segments is hypothesised to reduce time to functional recovery by 2 days in comparison with open surgery. With a power of 80% and alpha of 0.04 to adjust for interim analysis halfway the trial, a total of 250 patients are required to be randomised.

DISCUSSION

The ORANGE Segments trial is the first multicentre international randomised controlled study to compare short- and long-term surgical and oncological outcomes of laparoscopic and open resections in the posterosuperior segments within an enhanced recovery programme.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03270917 . Registered on September 1, 2017. Before start of inclusion.

PROTOCOL VERSION

version 12, May 9, 2017.

Study: International Multicentric Minimally Invasive Liver Resection for Colorectal Liver Metastases (SIMMILR-CRLM)

(1) Background: Here we report on a retrospective study of an international multicentric cohort after minimally invasive liver resection (SIMMILR) of colorectal liver metastases (CRLM) from six centers. (2) Methods: Resections were divided by the approach used: open liver resection (OLR), laparoscopic liver resection (LLR) and robotic liver resection (RLR). Patients with macrovascular invasion, more than three metastases measuring more than 3 cm or a solitary metastasis more than 5 cm were excluded, and any remaining heterogeneity found was further analyzed after propensity score matching (PSM) to decrease any potential bias. (3) Results: Prior to matching, 566 patients underwent OLR, 462 LLR and 36 RLR for CRLM. After PSM, 142 patients were in each group of the OLR vs. LLR group and 22 in the OLR vs. RLR and 21 in the LLR vs. RLR groups. Blood loss, hospital stay, and morbidity rates were all highly statistically significantly increased in the OLR compared to the LLR group, 636 mL vs. 353 mL, 9 vs. 5 days and 25% vs. 6%, respectively (p < 0.001). Only blood loss was significantly decreased when RLR was compared to OLR and LLR, 250 mL vs. 597 mL, and 224 mL vs. 778 mL, p < 0.008 and p < 0.04, respectively. (4) Conclusions: SIMMILR indicates that minimally invasive approaches for CRLM that follow the Milan criteria may have short term advantages. Notably, larger studies with long-term follow-up comparing robotic resections to both OLR and LLR are still needed.

Laparoscopic Minor Liver Resections for Hepatocellular Carcinoma in the Posterosuperior Segments Using the Rubber Band Technique

BACKGROUND

Although laparoscopic minor liver resections (LLR) of posterosuperior (PS) segments are technically challenging, several expert centers are increasingly performing this procedure. In the present study, we introduced novel techniques, including the rubber band traction method and positional changes, and compared surgical outcomes of LLR for hepatocellular carcinoma (HCC) located in PS segments with open minor liver resection (OLR).

METHODS

From January 2008 to August 2019, 113 patients underwent laparoscopic (n = 55) or open (n = 58) minor liver resections for single small HCCs (<5 cm) located in PS segments. Propensity score matching in a 1:1 ratio was conducted to minimize preoperative selection bias, and surgical outcomes were compared between the two groups.

RESULTS

There was no intraoperative mortality or reoperation in either group. One conversion to open surgery was necessary due to severe post-operative adhesions. The matched LLR group compared to OLR had significantly shorter operative time (215.16 vs. 251.41 min, P = 0.025), lesser blood loss (218.11 vs. 358.92 mL, P = 0.046), lower complication rate (8.1% vs. 29.7%, P = 0.018), and shorter hospital stay (7.03 vs. 11.78 days, P = 0.001). Intraoperative transfusion, R0 resection, resection margin, 5-year disease-free survival and 5-year overall survival were comparable.

CONCLUSION

Our standardized LLR provided improved short-term outcomes and similar long-term outcomes, when compared with OLR. With advanced techniques and accumulated surgical experience, LLR can be the first option for HCC in PS segments at expert centers.

Laparoscopic liver resection for colorectal liver metastases - short- and long-term outcomes: A systematic review

BACKGROUND

For well-selected patients and procedures, laparoscopic liver resection (LLR) has become the gold standard for the treatment of colorectal liver metastases (CRLM) when performed in specialized centers. However, little is currently known concerning patient-related and peri-operative factors that could play a role in survival outcomes associated with LLR for CRLM.

AIM

To provide an extensive summary of reported outcomes and prognostic factors associated with LLR for CRLM.

METHODS

A systematic search was performed in PubMed, EMBASE, Web of Science and the Cochrane Library using the keywords "colorectal liver metastases", "laparoscopy", "liver resection", "prognostic factors", "outcomes" and "survival". Only publications written in English and published until December 2019 were included. Furthermore, abstracts of which no accompanying full text was published, reviews, case reports, letters, protocols, comments, surveys and animal studies were excluded. All search results were saved to Endnote Online and imported in Rayyan for systematic selection. Data of interest were extracted from the included publications and tabulated for qualitative analysis.

RESULTS

Out of 1064 articles retrieved by means of a systematic and grey literature search, 77 were included for qualitative analysis. Seventy-two research papers provided data concerning outcomes of LLR for CRLM. Fourteen papers were eligible for extraction of data concerning prognostic factors affecting survival outcomes. Qualitative analysis of the collected data showed that LLR for CRLM is safe, feasible and provides oncological efficiency. Multiple research groups have reported on the short-term advantages of LLR compared to open procedures. The obtained results accounted for minor LLR, as well as major LLR, simultaneous laparoscopic colorectal and liver resection, LLR of posterosuperior segments, two-stage hepatectomy and repeat LLR for CRLM. Few research groups so far have studied prognostic factors affecting long-term outcomes of LLR for CRLM.

CONCLUSION

In experienced hands, LLR for CRLM provides good short- and long-term outcomes, independent of the complexity of the procedure.

The initiation, standardization and proficiency (ISP) phases of the learning curve for minimally invasive liver resection: comparison of a fellowship-trained surgeon with the pioneers and early adopters

BACKGROUND

Using the Ideal Development Exploration Assessment and Long-term study (IDEAL) paradigm, Halls et al. created risk-adjusted cumulative sum (RA-CUSUM) curves concluding that Pioneers (P) and Early Adopters (EA) of minimally invasive (MI) liver resection obtained similar results after fewer cases. In this study, we applied this framework to a MI Hepatic-Pancreatic and Biliary fellowship-trained surgeon (FT) in order to assess where along the curves this generation fell.

METHODS

The term FT was used to designate surgeons without previous independent operative experience who went from surgical residency directly into fellowship. Three phases of the learning curve were defined using published data on EAs and Ps of MI Hepatectomy, including phase 1 (initiation) (i.e., the first 17 or 50), phase 2 (standardization) (i.e., cases 18-46 or 1-50) and phase 3 (proficiency) (i.e., cases after 46, 50 or 135). Data analysis was performed using the Social Science Statistics software ( www.socscistatistics.com ). Statistical significance was defined as p < .05.

RESULTS

From November 2007 until April 2018, 95 MI hepatectomies were performed by a FT. During phase 1, the FT approached larger tumors than the EA group (p = 0.002), that were more often malignant (94.1%) when compared to the P group (52.5%) (p < 0.001). During phase 2, the FT operated on larger tumors and more malignancies (93.1%) when compared to the Ps (p = 0.004 and p = 0.017, respectively). However, there was no difference when compared to the EA. In the phase 3, the EAs tended to perform more major hepatectomies (58.7) when compared to either the FT (30.6%) (p = 0.002) or the P's cases 51-135 and after 135 (35.3% and 44.3%, respectively) (both p values < 0.001). When compared to the Ps cases from 51-135, the FT operated on more malignancies (p = 0.012), but this was no longer the case after 135 cases by the Ps (p = 0.164). There were no statistically significant differences when conversions; major complications or 30- and 90-day mortality were compared among these 3 groups.

DISCUSSION

Using the IDEAL framework and RA-CUSUM curves, a FT surgeon was found to have curves similar to EAs despite having no previous independent experience operating on the liver. As in our study, FTs may tend to approach larger and more malignant tumors and do more concomitant procedures in patients with higher ASA classifications than either of their predecessors, without statistically significant increases in major morbidity or mortality.

CONCLUSION

It is possible that the ISP (i.e., initiation, standardization, proficiency) model could apply to other innovative surgical procedures, creating different learning curves depending on where along the IDEAL paradigm surgeons fall.

Laparoscopic Liver Resections for Tumors in the Posterosuperior Segments: A Single-center Experience of 174 Consecutive Cases

BACKGROUND

Laparoscopic posterosuperior liver resection is a technically difficult and complex surgery. These patients are seen as poor candidates for laparoscopic surgery. This study aimed to show the safe and effective applicability of the posterosuperior segment resections by experienced surgeons in advanced centers.

MATERIALS AND METHODS

Patients who underwent laparoscopic posterosuperior liver resection between October 2011 and October 2019 at the Groeninge Hospital were evaluated retrospectively. Demographic and perioperative data were obtained from the prospectively maintained database. Resection of at least 3 consecutive Couinaud segments was accepted as a major surgery (trisegmentectomy). Postoperative complications were registered according to the Clavien-Dindo classification.

RESULTS

The median age of the 174 patients was 68 years [interquartile range (IQR): 60 to 75]. The semiprone position was used in the majority of operations (82.2%). Nonanatomic resection was performed in more than half of the operations (55.1%). A total of 5 patients underwent major hepatic resection. The median time of surgery was 150 (IQR: 120 to 190) minutes. Median blood loss was determined to be 150 (IQR: 50 to 300) mL. Malignancy was detected in 95% of the cases. The surgical margin was reported to be R0 in 93.3% of the specimens. The median hospitalization time was 4 (IQR: 3 to 6) days. The major complication rate was 1.7%, and only 1 patient died. Overall survival rates for patients who underwent a resection for colorectal liver metastases in the first and fifth years were 97.5% and 62.2%, and disease-free survival rates were 69.8% and 35.5%, respectively.

CONCLUSION

Laparoscopic resections in the posterosuperior segments can be performed safely in experienced hands with good short and long term (oncologial) outcomes.

Stepwise development of laparoscopic liver resection skill using rubber traction technique

BACKGROUND

To improve patient safety, we standardized our surgical technique and implemented a stepwise strategy for surgeons learning to perform laparoscopic liver resection (LLR). The aim of the study is to describe how the stepwise training approach and standardized LLR affects surgical outcomes.

METHODS

Data from 272 consecutive patients who underwent LLR from January 2009 to December 2017 were retrospectively reviewed. The risk-adjusted cumulative sum (RA-CUSUM) of surgical failures (conversion to laparotomy, blood transfusion, or Clavien-Dindo grade ≥3) and the CUSUM of operative time were used to determine optimal number of operations needed to achieve the best surgical outcome.

RESULTS

As the surgeon moved from simple to complex procedures, the complication rates, need for transfusions, and conversion rates did not increase over time. After 53 cases of minor LLR, a learning curve of 21 cases was achieved for right hepatectomy. Blood loss and operative time significantly improved thereafter. For minor anterolateral and posterosuperior segment resections, blood loss, and operative time significantly improved at the 37th and 31st case, respectively, given that the anterolateral segments had more complex surgeries performed.

CONCLUSION

Standardization of the operative technique and the implementation of a stepwise approach to training surgeons to perform LLRs could considerably improve surgical outcomes.

Major Laparoscopic Versus Open Resection for Hepatocellular Carcinoma: A Propensity Score-Matched Analysis Based on Surgeons' Learning Curve

BACKGROUND

Surgical complications for surgeons still in the learning phase of major laparoscopic liver resection (LLR) have been frequently observed. We aimed to compare perioperative and long-term outcomes of laparoscopic and open surgery based on the surgeons' learning curve for LLR after propensity score-matched (PSM) analysis.

METHODS

This was a retrospective study of all patients with a histologic diagnosis of hepatocellular carcinoma who underwent major hepatectomy between January 2013 and December 2018. A PSM analysis was used to compare the groups of patients who underwent LLR and open major liver resection (OLR) before and after the learning curve was maximized.

RESULTS

Among 405 patients, 106 underwent LLR and 299 underwent OLR. The learning curve was maximized after 42 cases. Compared with OLR, LLR had more liver-related injury and grade III or higher complications during the learning phase. The LLR group had less blood loss, fewer transfusion requirements, and fewer liver-related complications during the 'experienced' phase. Hospital stay was significantly shorter during and after maximization of the learning curve in LLR compared with OLR. Operative time was comparable in the two phases. Overall, LLR was associated with less blood loss, fewer complications, and shorter hospital stay compared with open surgery. There was no significant difference in long-term survival outcomes between the two groups.

CONCLUSIONS

LLR had a higher incidence of liver-related complications during the surgeon's learning phase compared with OLR. This association was significantly diminished with surgeon experience. Overall perioperative outcomes such as estimated blood loss, surgical complications, and hospital stay remained better for LLR compared with OLR.

Laparoscopic Liver Resection of Segments 7 and 8: from the Initial Restrictions to the Current Indications

Since the beginning of laparoscopic liver surgery, resection of the posterosuperior segments has been considered one of the most challenging procedure due to its difficult access. The main drawbacks of the laparoscopic approach to dome lesions are poor visualization, the difficulty of instrumentation and the greater complexity in the control of bleeding. In the evolution of minimally invasive techniques from hybrid techniques to the current purely laparoscopic approaches, the different authors have established gradually the currents indications and surgical techniques to operate these segments with a similar feasibility and safety than open approach. The standardization in the patient position, the use of intercostal trocars, the learning curve in laparoscopic liver surgery, the management of the hepatic blood flow and the refinement of the technique in the extrahepatic and intrahepatic Glissonean pedicle approaches, has allowed to leave behind the initial contraindications about the laparoscopic approach in these segments. In the present review of the literature, the accumulated experience of the different groups in minimally invasive liver surgery together with the technological advances in the different laparoscopic devices have facilitated the resection of tumors in segments 7 and 8 with similar and even better results than open surgery.

Impact of resection margins for colorectal liver metastases in laparoscopic and open liver resection: a propensity score analysis

BACKGROUND

There is no clear consensus over the optimal width of resection margin for colorectal liver metastases (CRLM), with evolving definitions alongside the advances on the management of the disease. In addition, data on the impact of resection margin after laparoscopic liver resection are still scarce.

METHODS

Prospectively maintained databases of patients undergoing open or laparoscopic CRLM resection in 7 European tertiary hepatobiliary referral centres were reviewed. After propensity score matching (PSM), the influence of 1 mm and wider margins on OS and DFS were evaluated in open and laparoscopic cohorts.

RESULTS

After PSM, 648 patients were comparable in each group. The incidence of positive margins (< 1 mm) was similar in open and laparoscopic groups (17% vs 13%, p = 0,142). Margins < 1 mm were associated with shorter RFS in open (12 vs 26 months, p = 0.042) and in laparoscopic group (13 vs 23, p = 0,002). Margins < 1 mm were associated with shorter OS in open (36 vs 57 months, p = 0.027), but not in laparoscopic group (49 vs 60, p = 0,177). Subgroups with margins ≥ 1 mm (1-4 mm, 5-9 mm, ≥ 10 mm) presented similar RFS in open (p = 0,251) or laparoscopic cohorts (p = 0.117), as well as similar OS in open (p = 0.295) or laparoscopic cohorts (p = 0.908). In the presence of liver recurrence, repeat liver resection was performed in 70 (30%) patients in the open group and 88 (48%) in the laparoscopic group (p < 0.001).

CONCLUSIONS

Our study suggests that a positive resection margin (less than 1 mm) width does not impact OS after laparoscopic resection of CRLMs as it does in open liver resection. However, a positive margin continues to affect RFS in open and laparoscopic resection. Wider margins than 1 mm do not seem to improve oncological results in open or laparoscopic surgery.

Laparoscopic or open approaches for posterosuperior and anterolateral liver resections? A propensity score based analysis of the degree of advantage

BACKGROUND

Benefits over the open technique are demonstrated for laparoscopic liver resections. Whether the degree of advantage is different for anterolateral and posterosuperior resections is investigated in this retrospective study.

METHODS

Laparoscopic anterolateral and posterosuperior resections (Lap-AL/Lap-PS) were compared with open (Open-AL/Open-PS) after propensity score matching. Mean/median differences of relevant parameters were calculated after bootstrap sampling. The degree of advantage was compared between anterolateral and posterosuperior resections and expressed as delta of differences (Δ-difference).

RESULTS

239 Lap-AL were compared with 239 matched Open-AL, and 176 Lap-PS with 176 matched Open-PS. Lap-AL showed reduced blood loss, morbidity, time to orally-controlled pain, mobilization and total stay; Lap-PS showed reduced blood loss, transfusions, morbidity, time to orally-controlled pain, mobilization, functional recovery and total stay. The degree of advantage of Lap-PS resulted significantly greater than Lap-AL blood loss (Δ-difference: 101 mL, p 0.017), transfusions (Δ-difference: 6.3%, p 0.008), morbidity (Δ-difference: 7.6%, p 0.034), time to orally-controlled pain (Δ-difference: 1 day, p 0.020) and functional recovery (Δ-difference: 1 day, p 0.042).

CONCLUSIONS

While both resulting in benefit, the advantage of laparoscopy is greater for posterosuperior than anterolateral resections. Despite their technical difficulty, these should be considered among the most worthwhile laparoscopic liver resections.

A Comparison of the Learning Curves of Laparoscopic Liver Surgeons in Differing Stages of the IDEAL Paradigm of Surgical Innovation: Standing on the Shoulders of Pioneers

OBJECTIVE

To compare the learning curves of the self-taught "pioneers" of laparoscopic liver surgery (LLS) with those of the trained "early adopters" in terms of short- and medium-term patient outcomes to establish if the learning curve can be reduced with specific training.

SUMMARY OF BACKGROUND DATA

It is expected that a wider adoption of a laparoscopic approach to liver surgery will be seen in the next few years. Current guidelines stress the need for an incremental, stepwise progression through the learning curve in order to minimize harm to patients. Previous studies have examined the learning curve in Stage 2 of the IDEAL paradigm of surgical innovation; however, LLS is now in stage 3 with specific training being provided to surgeons.

METHODS

Using risk-adjusted cumulative sum analysis, the learning curves and short- and medium-term outcomes of 4 "pioneering" surgeons from stage 2 were compared with 4 "early adapting" surgeons from stage 3 who had received specific training for LLS.

RESULTS

After 46 procedures, the short- and medium-term outcomes of the "early adopters" were comparable to those achieved by the "pioneers" following 150 procedures in similar cases.

CONCLUSIONS

With specific training, "early adapting" laparoscopic liver surgeons are able to overcome the learning curve for minor and major liver resections faster than the "pioneers" who were self-taught in LLS. The findings of this study are applicable to all surgical specialties and highlight the importance of specific training in the safe expansion of novel surgical practice.

Theory of Relativity for Posterosuperior Segments of the Liver

BACKGROUND

The accessibility to posterosuperior segments of the liver has traditionally constituted a restrain to adopt the laparoscopic approach in this setting. To overcome this challenge, multiple approaches have been reported in literature. Total transabdominal approach has been previously described for this purpose, even though the rationale to standardly adopt it and a technical depiction of how to achieve an optimal mobilization has never been specifically addressed.

METHODS

Total transabdominal purely laparoscopic approach to posterosuperior segments of the liver is presented, with detailed emphasis to the rotational motions targeted in laparoscopy. A literature review is presented to summarize all other possible accesses to posterosuperior area of the liver. The institutional series for the laparoscopic approach to Sg 7, Sg 6+7, and Sg8 is retrospectively described.

RESULTS

Three rotational motions of the liver are specifically addressed in a video presentation and described for the laparoscopic total-transabdominal approach; the local institutional series using this approach is presented. Other miscellaneous approaches identified from literature encompassing variations in operative position, transabdominal, transthoracic, and combined approaches are described.

CONCLUSIONS

Complete mobilization of the ligaments of the liver leads to a rotation of the transection line in front of the operator's view, allowing to achieve a safe total trans-abdominal laparoscopic approach to the posterosuperior ligaments of the liver, without compromising the vascular inflow control, the possibility to convert to open approach, nor requiring potentially harmful decubitus.

[Technical aspects of laparoscopic liver surgery : Transfer from open to laparoscopic liver surgery]

BACKGROUND

Laparoscopic surgery has become the standard for most visceral surgery procedures in many hospitals. Now, liver resections are also being increasingly carried out laparoscopically. The advantages of the laparoscopic technique have been demonstrated in numerous case series and in a recent randomized controlled trial.

AIMS

The aim of this review article is to present the available techniques for laparoscopic liver surgery (LLS).

METHODS

The technical variations reported in the literature as well as the own experience with LLS are reported.

RESULTS

Optimal patient and trocar positions are crucial for successful LLS and they are chosen according to the planned type of liver surgery: the literature offers several options in particular for surgery of the cranial and dorsal liver segments. As for open liver surgery, a restrictive volume management and the application of the Pringle maneuver are helpful to reduce intraoperative blood loss in LLS. In addition, several dissection techniques have been adopted from open liver surgery. The Cavitron Ultrasound Surgical Aspirator (CUSA™) is particularly suitable for parenchymal dissection close to major vascular structures, since it guarantees a meticulous parenchymal dissection with minimal vascular injuries.

CONCLUSION

The developments of minimally invasive surgery nowadays allow complex liver resections, which can mostly be performed comparable to open liver surgery. Hopefully, minimally invasive liver surgery will further develop in Germany in the near future, since it offers several advantages over open liver surgery.