A Comparison of Three-Dimensional Visualization Systems and Two-Dimensional Visualization Systems During Laparoscopic Cholecystectomy: A Narrative Review

Abstract

Background:

Laparoscopic cholecystectomy is a common procedure for the definitive treatment for cholecystitis and symptomatic cholelithiasis. One advancement in minimally invasive surgery has been the development of three-dimensional (3D) visualization systems to provide stereopsis. It is yet to be determined whether this innovation is beneficial to the surgeon or simply just a gimmick. This narrative review aims to answer the following research question, what is the impact of 3D visualization systems on surgical efficiency compared with two-dimensional visualization systems in laparoscopic cholecystectomy?

Methods:

Through a broad literature search it was determined that operative time and intraoperative errors have been used in published research to assess intraoperative efficiency.

Results:

Studies published to date have used operative time, intraoperative errors, and intraoperative bleeding as current measures for intraoperative efficiency. Previous meta-analysis have shown a slight improvement in operative time for 3D visualization systems; however, subsequent randomized control trials have not shown a significant difference in operative time. Reporting of intraoperative errors has been quite subjective and a difference between visualisation modality has not been shown.

Conclusion:

3D visualization systems have shown a minor improvement in operative time compared with traditional laparoscopic systems and it is unlikely to be of any clinical significance. Studies that measure intraoperative error vary greatly in what they report, and which assessment tool is used. Across existing literature, studies do not control for surgeon's experience, elective/emergent cases, and grade of gallbladder/difficulty. Further research is required, using novel tools for assessment in laparoscopic cholecystectomy to determine intraoperative differences through objective and quantitative variables.

Background

Cholecystectomy is the definitive treatment for patients with symptomatic cholelithiasis. Since the introduction of laparoscopic cholecystectomy in the 1990s, the rates of cholecystectomy in Australia rose to 24% compared with the pre-laparoscopic era.¹ Minimally invasive surgery (MIS) has been proven to show significant benefits in terms of aesthetic results, reduced postoperative morbidity and mortality, reduced hospital stays, significantly reduced wound infection rates and pneumonia rates as well as early return to normal activity.²

For the past 20 years, there have been significant technological developments in minimally invasive instrumentation and video capture devices, with general agreement that this has improved patient outcomes. Although this can be subjectively true from the surgeon's perspective, the evidence for a link between technological developments in MIS and improved patient outcomes is not strong as it can be quite difficult to prove.

One such advancement in MIS has been the development of three-dimensional (3D) visualization systems to provide surgeons with stereopsis during laparoscopic procedures. Traditionally, laparoscopic surgery has utilized two-dimensional (2D) visualization systems, which do not provide depth perception. Here, the surgeon is required to mentally transform 2D images to 3D images through motion parallax, position of instruments and shading from shadows. This can represent a significant cognitive workload for the surgeon, particularly during prolonged or difficult operations. 3D visualization systems overcome this by using two separate optic channels to provide unique images to the right and left eye from each camera. This results in binocular vision as occurs during visualization in the real world. The subtle changes in these images provide the surgeon with depth perception and it was anticipated that 3D technology would translate to greater accuracy and speed in manual skills. 3D cameras were designed to enhance the visual experience during operations, and although many surgeons argue that these advantages lead to better operative images and improved patient outcomes, objectively corroborating this hypothesis is challenging. Furthermore, surgeons with refractive errors such as myopia, astigmatism, or hyperopia cannot use 3D systems and some operators experience user discomfort with the 3D system, especially with visual strain, headaches, or dizziness. In most cases these symptoms subside with practice and ongoing use.³

Most evidence supporting the advantages of 3D systems comes from observational studies and anecdotal evidence. Overall, previous studies have shown that there is limited clinically significant difference in patient outcome between 2D and 3D visualization systems in laparoscopic cholecystectomy, especially, given already outstanding safety with traditional laparoscopic techniques differences are difficult to measure.³ However, many questions remain unanswered and any conclusions about the merits of a 3D camera system require further investigation.

Isolating the impact of camera technology on patient outcomes is complex when considering the multiple factors that effect this. This narrative review aims to answer the following research question: What is the impact of 3D visualization systems on surgical efficiency compared with 2D visualization systems in laparoscopic cholecystectomy? The objective of this narrative review is assess and compare the accuracy and precision of surgical maneuvers performed with 3D and 2D visualization systems in laparoscopic cholecystectomy, using objective measurements.

Methods

A broad review of existing literature was completed using PubMed, Embase, and Cochrane were the databases used for the narrative review. The following search terms were applied on the 7th of May 2023: (1)

“Imaging, Three-Dimensional”[Mesh] AND “Cholecystectomy, Laparoscopic”[Mesh]

(2)

(laparoscop* OR endoscop*) AND cholecystectom* AND (three-dimension* OR 3-dimension* OR 3D) AND (two-dimension* OR 2-dimension* OR 2D)

(3)

cholecystectom* AND (three-dimension* OR 3-dimension* OR 3D)

After duplicate results were removed, relevant articles were screened through an abstract review (Fig. 1). Further relevant articles were then reviewed through full-text review.

FIG. 1.

Search strategy.

Inclusion criteria for this narrative review were all study types, including systematic reviews, meta-analyses, randomized control trials (RCTs), and prospective and retrospective cohort studies that compare 2D and 3D visualization systems in laparoscopic cholecystectomy. The search was inclusive of all study to determine which intraoperative outcomes have been assessed when comparing 2D and 3D visualization systems in laparoscopic cholecystectomy. The search excluded studies that compare laparoscopic cholecystectomies with either visualization system with any other alternative surgical procedure, that is, robotic, mini-laparotomy for cholecystectomy, or open procedures.

Results

After analyzing the existing literature comparing 2D and 3D visualization systems in laparoscopic cholecystectomy, two common outcomes emerged for assessing intraoperative efficiency, operative time, and intraoperative error rates.

Operative time

It was postulated that with increased depth perception in 3D systems, there would be increased accuracy and speed of surgical movements resulting in decreased operative times. Retrospective analysis comparing 2D and 3D laparoscopic cholecystectomies by Yun et al. showed a significant decrease in operative time of 32 minutes when using 3D systems.⁴ This would signify a significant advantage in 3D laparoscopic cholecystectomy. Subsequent systematic review and meta-analysis of 5 RCTs by Davies et al. showed a statically significant decrease in procedure time of 4.23 minutes when using 3D systems compared with 2D without an increase in intraoperative bleeding, conversion to open or postoperative complications.⁵ There was significant heterogeneity reported between the studies where differences could be due to inconsistencies across the studies that included aspects of the procedure that would not be affected by visualization system such as time for intraoperative cholangiogram (IOC), insertion of laparoscopic ports, or skin suturing. This meta-analysis showed 3D systems resulted in the operation being completed quickly without compromising safety, but this improvement is unlikely to offer any clinical significance for the patient or surgeon. Subsequent studies published after this meta-analysis reveal varying results when comparing 2D and 3D visualization systems. Dunstan et al. completed an RCT of 109 laparoscopic cholecystectomy cases comparing high-definition 3D with 4K 2D visualization systems, which revealed no differences in operative time across 3 consultant surgeons.⁶ The study collected intraoperative grading of the gallbladder and only reported that grade 3 gallbladders (defined as “dense adhesions, duodenum or bile duct adherent to gallbladder, active inflammation, contracted gallbladder, empyema, dense adherence to liver, difficult abnormal or unclear anatomy, or gallstone in Hartmann's pouch or gallbladder neck”) had no difference in operative time across either visualization system.⁶ In addition, this study used 3 consultant surgeons and did not comment on experience of these surgeons or comment whether these cases were completed as emergent or elective surgeries. Given the small sample size, a significant difference in emergent or elective surgeries could significantly bias the results.

Parshad et al. undertook an RCT comparing 3D and 4K 2D visualization systems across several general surgery procedures.⁷ They randomized 60 patients due for laparoscopic cholecystectomy and determined that there was no difference between the two visualization systems for total operative time and identified steps, even when controlled for gallbladder grade. This study defined total operative time as skin insertion for Veress port to skin closure of last port site, which would introduce confounding factors, including variable IOC time and skin suturing time, which would not be affected by visualization system.⁷ In addition, limited conclusions can be drawn from this study as it did not control for surgeon's experience, elective versus emergent cases or operator's experience and, therefore, limited conclusions can be made regarding overall operative time. Moreover, Tauriainen et al. undertook a prospective cohort study of 241 consecutive laparoscopic cholecystectomy cases, where 3D systems resulted in an increased procedure time of 6.1 minutes.⁸ Again, this study was not controlled for surgeon experience or gallbladder grade, with a lower proportion of operations being completed by a senior surgeon and higher rates of acute cholecystitis in the 3D group that significantly biases findings. The only study that controls for surgeon's experience is by Curro et al.'s RCT that compares 2D and 3D systems in novice and experienced surgeons.⁹ This study found that operative performance time is not influenced by 3D systems in laparoscopic cholecystectomy, although, in novice surgeons, there is a benefit of 12 minutes per operation and suggests 3D systems are useful when gaining experience in laparoscopic cholecystectomy. In addition, there was a statistically significant benefit in decreased time to complete identified steps, including Calot's triangle dissection and gallbladder removal for novice surgeons and suggest 3D systems may prove useful when first learning how to complete laparoscopic cholecystectomy.

Ultimately, there is slight improvement in operative time when using 3D systems compared with 2D; however, it is uncertain if this of any clinical consequence. 3D systems would likely benefit the early career surgeon in laparoscopic cholecystectomy but given studies are lacking in controlling for experience further research in this area is required. Studies to date are also lacking in controlling for grade of gallbladder and whether cases were elective or emergent, both of which would have significant impact on operating time. Furthermore, studies are inconsistently including steps in overall operating time that would not be affected by visualization system such as port insertion, IOC, or skin suturing, which would bias results.

Intraoperative complications

Intraoperative findings have been reported inconsistently across published literature when comparing 2D and 3D visualization systems in laparoscopic cholecystectomy. When assessing for intraoperative errors Dunstan et al. found no difference between 2D and 3D systems in laparoscopic cholecystectomy.⁶ This study used the Technical Skills Checklist, which involves calculating a weighted score for minor errors (bile spillage, diathermy injury to liver, incomplete clipping, injury to cystic duct or artery, etc.) and significant errors (major vessel or major ductal injury, other visceral injury, etc.). It was determined that errors increased as the grade of the gallbladder, which would be expected.

Similarly, Davies et al. were able to determine that there was no difference between intraoperative errors between 2D and 3D systems in laparoscopic cholecystectomy.⁵ They identified two studies that reported on intraoperative errors and had low heterogeneity. Schwab et al. used observational clinical human reliability analysis (OCHRA) and Hanna et al. determined errors during identified step by senior surgeon supervising the case.^10,11 Schwab et al. determined that gallbladder grade had an effect on number of errors and that there was no difference in each identifiable error between 2D and 3D laparoscopic cholecystectomies, except for a slight increase in gallbladder perforation with stone spillage in 3D laparoscopic cholecystectomy.¹¹ These findings would be of little clinical significance.

Furthermore, in the meta-analysis of five studies, Davies et al. showed that there was no difference in the rates of bleeding or difference in gallbladder perforation when using 3D or 2D systems.⁵ Furthermore, Tauriainen et al. demonstrated that there was a statistically significant increased risk of bile duct injury with 2D systems when compared with 3D.⁸ This represents a potentially serious risk of complication as bile injury is associated with increased mortality and morbidity.⁸ However, other studies have shown that this has not translated into poorer patient outcomes.⁵

Thus, studies to date have been inconsistent in reporting of intraoperative errors and there has been a lack of standardizing of defining an intraoperative error. 3D systems were hypothesized to provide better identification of surgical planes, in turn, resulting in decreased bleeding; however, this is not the case. There is a dearth in studies that assess subtle measures of operator efficiency such as instrument changes, grasping attempts, and suturing difficulties, and further research is needed to assess for these quantifiable variables.

Discussion

Currently, there is conflicting evidence of the intraoperative benefit of using 3D visualization systems in laparoscopic cholecystectomy when compared with 2D visualization systems. Although, one meta-analysis showed an improvement in operative time, it is unclear whether this benefit is due to improvements of a particular step in the operation or whether there is an overall improvement across the operation. Subsequent studies have not replicated similar benefits that could reflect improvements in 2D technology overcoming previous limitations seen in high-definition standards in both the endoscope and screen. Novice surgeons using 3D visualization systems have decreased operative time, which could be reflective of demographic differences among surgeons, where younger generations are “used to 3D” through gaming compared with older generations.

Alternatively, it could be explained that given the world is viewed with stereopsis, 3D systems provide an easier transition to MIS as 2D is an unnatural form of viewing and requires significant training to complete complex tasks. Interestingly, studies have been deficient in controlling for gallbladder grade, surgeon's experience, and elective/emergent cases and further studies that control these factors are needed to reliably compare visualization systems in laparoscopic cholecystectomy. In addition, any difference in 2D and 3D visualization system is likely only be detected in difficult and prolonged cases or completion of complex tasks such as laparoscopic suturing, where operator fatigue becomes a factor and results in an increased number of errors.

Based on studies published to date, few differences in intraoperative errors have been shown when using 3D systems compared with 2D systems in laparoscopic cholecystectomies. Simulation of laparoscopic skills using 3D visualization systems have reported decreased error rates in both novice and experienced surgeons; however, this has not translated into improved error rates in laparoscopic cholecystectomy.^12,13

Furthermore, the surgical checklist for laparoscopic cholecystectomy used by Dunstan et al. and OCHRA used by Schwab et al. relies on subjective measures that can only be assessed by other senior surgeons.^14,15 The errors identified by these checklists can be quite subjective to the severity of the error and these “errors” can often be managed intraoperatively. For example, in the surgical checklist for laparoscopic cholecystectomy, a minor error is liver injury by diathermy and a similar major error is liver injury with bleeding and can be scored as corrected error or uncorrected error if it occurs. The degree to which one would expect bleeding after diathermy injury to the liver is small, and surgeons accept small amounts of bleeding during laparoscopic cholecystectomy. Therefore, 1 surgeon may choose to allow small bleedings to resolve without any additional intervention and then would be scored with an uncorrected error, while being the appropriate course of action. Often these are very low incidence and studies would need tens of thousands of participants to determine a statistically significant result, with current studies have been of low participants.

Moreover, traditional modes of surgical teaching rely on the master–apprentice model, with feedback being qualitative and prone to the halo effect, and there is a need to objectively measure surgical efficiency. Currently, The Objective Structured Assessment of Technical Skills and The Global Operative Assessment of Laparoscopic Skills are used in assessment of skill in laparoscopic cholecystectomy; however, both provide subjective measures of general surgical skills and are only validated for assessment by experts.^16–18

Clearly, there is a need for standardized assessment tools that use objective or quantitative variables and can be used by nonexpert surgeons in laparoscopic cholecystectomy. This has been exemplified by the call from the European Association for Endoscopic Surgery to develop a performance assessment tool as a research priority.¹⁹ If an assessment tool is developed this would be able to provide reliable data for when comparing the efficiency of 2D and 3D systems.

Therefore, further studies are required to use novel tools for assessment in laparoscopic cholecystectomy to determine intraoperative differences. It is proposed that novel pilot study that incorporates intraoperative quantifiable steps such as number of missed diathermy hook attempts, number of missed staple attempts, or number of failed grasps as well as complication rates and accuracy of surgical plane dissections. Furthermore, future studies should include collaborative studies involving multiple surgical centers to increase the sample size and diversity of patient populations and provide more generalizable results.

Moreover, automation of objective measure in surgical assessment for laparoscopic cholecystectomy would provide effective feedback for surgeons and aid ongoing professional development. As laparoscopic surgery relies on an active video stream, there is an opportunity to collect large volumes of laparoscopic operations and be assessed by AI. Lavanchy et al. was able to show machine learning is able to qualitatively predict surgical skill with 87% accuracy by using quantitative measures, including area of movement, range of movement, and positional changes in laparoscopic cholecystectomy.²⁰ The development AI algorithms can be used to analyze surgical images and videos captured by both 3D and 2D camera systems.

These algorithms can identify and measure various parameters such as tissue manipulation, instrument movement, depth perception, and anatomical landmarks. By comparing these parameters between 3D and 2D systems, AI can provide quantitative insights into the differences in performance and potential benefits of 3D visualization. AI-based tools can assess surgical skills by analyzing recorded surgical procedures. These tools use computer vision and machine learning techniques to evaluate factors such as instrument movement smoothness, precision, and hand-eye coordination. By applying these tools to operations performed with 3D and 2D camera systems, it might be possible to compare the technical proficiency and performance of surgeons using each modality.

AI can be used to develop predictive models based on historical surgical data. By training the models on a data set that includes operations performed with both 3D and 2D systems, it may be possible to predict the outcomes and potential complications associated with each modality. These predictive models can help in understanding the impact of the camera system on patient outcomes and guide decision-making. Hence, should a validated assessment tool be developed and applied to AI technology, this would represent a significant paradigm shift in ongoing surgical assessment.

However, development of such technology will require robust data collection, algorithm training, and validation processes, which represent a significant time and monetary commitment. Collaborating with surgeons, researchers, and AI experts would be necessary to make this a reality and to create accurate and reliable assessment tools for evaluating the comparison between 3D and 2D operating camera systems.

Conclusion

Despite many anecdotal reports from surgeons that 3D laparoscopic systems help increasing efficiency in cholecystectomy, existing literature does not indicate a clear clinical benefit toward using 3D visualization systems in laparoscopic cholecystectomy when compared with 2D systems. This is likely as existing studies have only used intraoperative outcomes as an objective intraoperative measure or have otherwise used subjective outcomes. There is a dearth in the literature of a study that can accurately assess intraoperative efficiency in laparoscopic cholecystectomy through measurement of objective quantitative variables, while controlling for grade of the gallbladder and experience of the surgeon to determine whether 3D visualization systems offer any benefit to the surgeon. Further studies in this area will require novel tools that can assess objective quantifiable intraoperative outcomes.

Footnotes

Acknowledgment

This article has been approved by all authors and has not been submitted for publication elsewhere.

Authors' Contributions

Methodology (equal), writing—original draft (lead), conceptualization (supporting), investigation (equal), and writing—review and editing (supporting) by M.P. Methodology (equal), writing—original draft (supporting), conceptualization (lead), investigation (equal), writing—review and editing (lead), and supervision (lead) by T.J.H.

Disclosure Statement

No competing financial interests exist.

Funding Information

Nil funding has been sought for the production of this article.

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