Keywords surgical training - laparoscopic cholecystectomy - bile duct - critical view of safety
(CVS).
Technological advances and web-based applications have truly revolutionized the field
of surgical education. In an effort to enhance the learning experience, traditional
tools, like the time-honored atlas of surgical operations, have given way to contemporary
solutions, like simulators and virtual reality.[1 ] Undoubtedly, the audiovisual interaction offered by modern technology cannot be
surpassed by books and amphitheater lectures.
Surgical videos are an example of the benefits of multimedia in the learning process
and have been established as a modern educational module. Ninety percent of surgeons
and trainees watch videos to prepare for surgical cases and studying, usually on public
platforms like YouTube (www.youtube.com ).[2 ]
[3 ]
[4 ] However, the true value of public video libraries, as source of medical information
or surgical technique, has been questioned, due to concerns for low quality, non—peer-reviewed
material, or nonadherence to guidelines.[5 ]
[6 ]
[7 ]
[8 ]
[9 ]
[10 ]
To date, only a small number of studies have evaluated the quality of laparoscopic
cholecystectomy videos on popular platforms (YouTube, Vimeo, etc.), with regard to
the CVS principles.[1 ]
[11 ]
[12 ]
[13 ]
[14 ] They have found alarmingly low rates of correct CVS application, as low as 10 to
28%. However, selection of videos in these studies was based on the search term “laparoscopic
cholecystectomy” alone, without any reference to the CVS itself.
The aim of our study was to assess the educational value of laparoscopic cholecystectomy
videos on YouTube, that explicitly reported successful CVS achievement. These videos
were used for a simulated decision-making exercise, aimed at evaluating surgical trainees'
perceptions of the CVS criteria.
Materials and Methods
Introduced in 1995, the CVS is a method of target identification used in laparoscopic
cholecystectomy, to avoid bile duct and vascular injuries, due to misidentification
of anatomical structures in the hepatocystic triangle.[15 ] Secure identification of the cystic structures depends on three requirements: (1)
clearance of the hepatocystic triangle of all fibrofatty tissue, (2) identification
of two and only two tubular structures entering the gallbladder wall, and (3) dissection
of the lower third of the gallbladder off the cystic plate. Each criterion is awarded
0 to 2 points, for a maximum of six points.[16 ] Scores of 5 or 6 are considered a satisfactory CVS, allowing safe ligation of the
cystic duct and artery. Scores of 0 to 4 require further dissection or a bail-out
technique.[17 ]
Using the keywords “critical view of safety” and “laparoscopic cholecystectomy,” the
YouTube platform was searched on May 21st , 2020, to identify operative videos, which explicitly reported a satisfactory CVS,
either in the title, the description, or embedded on the video itself. Eligible were
videos of live surgical procedures with adequate play time to enable assessment of
the dissection of the hepatocystic triangle and demonstration of the CVS criteria.
Animations, lectures, conference presentations, and educational material provided
by scientific societies were excluded. No restrictions on age, gender, ethnicity,
or experience of the primary surgeon were imposed. Both videos of elective and acute
cholecystitis cases were acceptable. For each video, the following data were extracted:
URL, number of views, likes, dislikes and comments, gender, and country of the primary
surgeon.
Three consultant surgeons, trained on and exclusively performing the CVS approach,
jointly scored the videos, using the six-point scale. Videos were judged as a whole,
therefore, points were given if the relevant CVS requirement was present either in
the anterior or the posterior view. Each video was subsequently characterized as either
“Pass” (5–6) or “Fail” (0–4). A subanalysis was performed, to assess whether number
of views, likes and dislikes were associated with rates of successful CVS.
The video URLs were then given to 10 trainees [five junior (years 1–3) and five senior
(years 4–5) residents], blinded to the consultants' assessment. After watching a training
module on CVS rationale and criteria with operative examples, they were instructed
to view the videos, until the cystic structures were clipped and divided, to score
each CVS criterion and answer the binary question “Would you divide the cystic structures? ” by “Yes” or “No.”
Ιnter-observer agreement was calculated for each resident as percent agreement and
Randolph's kappa, by comparison with consultants' score.[18 ] Intra-observer agreement among trainees was also calculated, comparing their CVS
evaluation and decision to divide or not the cystic structures. To further determine
which CVS criterion was the most difficult to identify, the gradings for each criterion
were compared among residents by Randolph's kappa. Statistical analysis was performed
on SPSS ver 20.0 (IBM Corp.). Values of kappa coefficient were interpreted as follows:
no agreement (0–0.20), minimal agreement (0.21–0.40), weak agreement (0.41–0.60),
moderate agreement (0.61–0.80), strong agreement (0.81–0.90), and almost perfect agreement
(>0.90).
Results
The 30 highest ranking videos, by number of views, were included in the study ([Table 1 ]). Median number of views was 2,313 (range 331–58,541). All surgeons were males.
Table 1
Characteristics of included YouTube videos
No
Views
Likes
Dislikes
Comments
Surgeon gender
Country
Setting
1
58,541
368
46
64
Male
India
Elective
2
33,183
90
19
8
Male
United States
Elective
3
28,374
78
4
3
Male
Egypt
Elective
4
28,311
141
8
3
Male
India
Elective
5
10,171
46
6
15
Male
Turkey
Acute
6
9,657
35
2
5
Male
Turkey
Elective
7
7,800
54
6
0
Male
Egypt
Elective
8
6,049
29
7
4
Male
Italy
Elective
9
4,424
24
2
2
Male
Italy
Acute
10
3,257
6
0
3
Male
India
Elective
11
3,181
24
2
4
Male
Turkey
Acute
12
2,951
8
2
0
Male
UK
Elective
13
2,409
23
5
5
Male
India
Elective
14
2,408
18
1
1
Male
United States
Elective
15
2,374
51
1
4
Male
Argentina
Elective
16
2,251
28
0
3
Male
Argentina
Elective
17
1,914
11
2
0
Male
Turkey
Elective
18
1,515
17
0
5
Male
Italy
Acute
19
1,324
4
0
0
Male
India
Elective
20
1,080
1
2
0
Male
India
Elective
21
980
26
0
11
Male
India
Elective
22
925
32
2
6
Male
Italy
Elective
23
888
5
0
0
Male
Greece
Elective
24
885
32
1
4
Male
India
Elective
25
864
12
0
1
Male
United States
Elective
26
805
24
0
0
Male
Argentina
Elective
27
604
5
0
2
Male
Turkey
Acute
28
516
5
0
1
Male
Turkey
Elective
29
344
2
1
0
Male
India
Acute
30
331
2
0
0
Male
United States
Elective
Twenty-one videos (70%) were judged by the consultants as having properly obtained
the CVS (scores of 5–6), whereas 9 (30%) were deemed unsatisfactory (scores of 0–4).
Out of 24 elective and six acute cholecystitis cases, the CVS was not obtained in
5 (20.8%) and 4 (66.7%), respectively. No statistical association was observed between
number of views, likes or dislikes with completion rates of CVS.
[Table 2 ] shows the trainees' evaluation. Overall “Pass” ratings ranged between 30 and 76.7%,
while decision to proceed with division of the cystic structures ranged between 53.3
and 83.3% (discrepancy in 45/300 assessments). The inter-observer agreement between
consultants and residents is shown in [Table 2 ] and [Fig. 1 ]. Percent agreement ranged between 53 and 80% (mean 69.7 ± 9.2%), whereas Randolph's
kappa between 0.07 and 0.60 (mean 0.39 ± 0.18). Intra-observer agreement between the
trainees' CVS scoring and the decision to divide the structures ranged between 63.3
and 100% (as percent agreement) and 0.27 to 1 (as Randolph's kappa). ([Fig. 2 ]). Level of trainee surgical experience was not associated with higher levels of
inter- and intra-observer agreement. For the three CVS requirements, inter-observer
agreement was minimal for dissection of the cystic plate (k = 0.26) and triangle clearance (k = 0.39) and weak for the identification of 2 structures (k = 0.42).
Table 2
Inter- and intraobserver agreement between consultants and trainees
Experience
Pass (5–6)
n
(%)
Fail (0–4)
n
(%)
% Agreement
Inter-obsever agreement (kappa)
Would you clip? yes (%)
% Agreement
Intra-observer agreement (kappa)
Consultants
21 (70)
9 (30)
Trainee no 1
Senior
10 (33.3)
20 (66.7)
63.3%
0.27
21 (70)
63.3%
0.27
Trainee no 2
Senior
15 (50)
15 (50)
80%
0.60
16 (53.3)
96.7%
0.93
Trainee no 3
Senior
19 (63.3)
11 (36.7)
60%
0.20
19 (63.3)
93.3%
0.87
Trainee no 4
Senior
18 (60)
12 (40)
70%
0.40
18 (60)
100%
1
Trainee no 5
Senior
17 (56.7)
13 (43.3)
80%
0.60
25 (83.3)
73.3%
0.47
Trainee no 6
Junior
16 (53.3)
14 (46.7)
76.7%
0.53
19 (63.3)
90%
0.80
Trainee no 7
Junior
18 (60)
12 (40)
76.7%
0.53
18 (60)
100%
1
Trainee no 8
Junior
23 (76.7)
7 (23.3)
73.3%
0.47
23 (76.7)
93.3%
0.87
Trainee no 9
Junior
18 (60)
12 (40)
63.3%
0.27
25 (83.3)
76.7%
0.53
Trainee no 10
Junior
9 (30)
21 (70)
53.3%
0.07
20 (66.7)
63.3%
0.27
Fig. 1 Summary of trainees' assessment of the top-30 YouTube CVS videos [pass = adequate
CVS (5–6), fail = inadequate CVS (0–4); as judged by consultants]. CVS, critical view
of safety.
Fig. 2 Summary of trainees' responses to the binary question “Would you divide the cystic
structures?” [pass = adequate CVS (5–6), fail = inadequate CVS (0–4); as judged by
consultants]. CVS, critical view of safety.
Discussion
Previous studies assessing laparoscopic cholecystectomy videos on internet platforms
found disappointing rates of proper CVS application. Lee et al analyzed 73 YouTube
videos, grading 15% as “good,” 55% as “moderate” and 30% as “poor.”[11 ] However, demonstration of the CVS requirements was not reported by the 6-point scale,
but rather on a 0 to 3 scale, and was incorporated into the overall scoring. Deal
et al reviewed 40 representative videos on YouTube, Vimeo and the SAGES library, of
variable technical performance.[13 ] Faculty expert ratings showed that only 12.5% achieved CVS scores of ≥5, while 85%
scored ≤3. Moreover, an analysis of 139 YouTube videos by the same team, using crowd-sourcing,
found no statistical correlation between number of views, likes, dislikes or subscribers
and the completion of CVS.[12 ] Rodriguez et al analyzed the top ten listed YouTube videos and found only one to
show a satisfactory CVS (≥5), while Chavira et al reviewed a total of 77 YouTube,
WebSurg and GIBLIB videos, showing successful CVS rates in 27.7, 44.4, and 40%, respectively.[1 ]
[14 ]
The aforementioned studies used the search term “laparoscopic cholecystectomy” during
the selection process. By combining the keywords “critical view of safety” AND “laparoscopic cholecystectomy,” our analysis included only those videos that explicitly
reported the successful application of the CVS. Of the top-30 most popular videos
by number of views, 70% were evaluated by consultants as having conclusively achieved
a CVS score of 5 or 6. Expectedly, this percentage was higher compared with similar
studies of unselected cases. However, our results showed that a significant proportion
of surgeons (30%), although claiming a satisfactory CVS, still misunderstood the core
concept in practice.
In addition, similar to previous studies, the number of views, likes, and dislikes
was not associated with successful CVS rates.[1 ]
[12 ] Indeed, the significant difference in views between the first and last video (58,541
vs. 331) shows that viewers rarely scroll beyond the first few results.[14 ] Even more importantly, neither likes nor dislikes reflect the actual quality of
the content. Public video libraries should therefore be used very judiciously, since
the uploaded content is usually not peer-reviewed. Dedicated surgical websites and
operative videos produced by academic institutions or official surgical societies
are of higher educational value and should be preferred as training material.
The simulated decision-making exercise revealed certain interesting results. Between
trainees and consultants, inter-observer agreement ranged from minimal to moderate.
Generally, trainees tended to give lower marks overall, compared with consultants.
To some extent, this fact may be attributed to a more cautious evaluation of the CVS
criteria by surgeons in the beginnings of their learning curve. On the other hand,
higher level of surgical training was not associated with higher inter-observer agreement
rates, as might have been expected.
Yet, even more contradictory was the discordance between CVS scores and decision to
divide the cystic structures. Despite the explanatory training module prior to the
exercise, in 15% of cases the trainees would indeed proceed to ligation, even though
their awarded CVS score was <5. This misconception of the CVS rationale is a hazardous
gap in surgical training and could ultimately reflect an unsafe practice.
While the learning curve for mastering the CVS has yet to be determined, by analysis
and comparison of operative notes and videos we do know that even experienced surgeons
may lack full understanding of the three steps that constitute a proper CVS.[19 ]
[20 ] Given the burden of BDI on the health care system and patients' long-term quality
of life, education of surgeons toward the correct application of the CVS cannot be
overemphasized.[19 ]
[21 ] Tutorials with structured curriculum are necessary to highlight the rationale behind
the CVS requirements and promote a culture of safety in laparoscopic cholecystectomy.
Either in the form of lecture or video, they have been shown to increase rates of
successful CVS and improve confidence among trainees.[21 ]
[22 ]
[23 ]
[24 ]
[25 ]
[26 ]
Furthermore, we found considerable variation in the evaluation of each CVS criterion,
with least agreement for adequate dissection of the cystic plate, similar to Mascagni
et al.[27 ] Mobilization of the lower third of the gallbladder off the liver bed is essential,
to secure that the purported cystic structures do not reenter the hepatic parenchyma
at a higher level. However, there is not one single reason why surgeons fail to obtain
a proper CVS. Nakazato et al found that the most common cause for an incomplete CVS
was the inadequate cystic plate dissection, Carr et al found the inadequate clearance
of the hepatocystic triangle, while Nijssen et al found the inability to recognize
two and only two structures.[20 ]
[25 ]
[26 ] Equal emphasis on all three requirements is therefore necessary.
Inconsistency and subjective interpretation of the CVS criteria hide a dangerous trap,
that could lead to vasculobiliary injuries. A conceptual framework, developed by expert
academic surgeons, defined the essential competencies required to establish the proper
CVS.[28 ] This framework includes cognitive elements and potential errors, related to situational
awareness, decision-making and action-oriented subtasks, and may serve as the basis
for surgical training, assessment tools, and quality-control metrics.
Our study was limited by the small number of participants, all of them trainees at
a single surgical department, as well as small number of videos (n = 30). We also narrowed the selection of surgical videos to YouTube and chose not
to include specialized, online surgical libraries. The videos were included solely
on the basis of popularity and were not assessed for their technical quality or surgical
competency, thus better reflecting real-world situations. Nevertheless, they were
evaluated by experienced consultants using the recommended six-point CVS scale. Finally,
our training module was similar in concept to the video tutorial by Deal et al, but
has not been validated as an educational tool.[24 ]
Conclusion
Promotion of a culture of safety should be the very core of laparoscopic cholecystectomy
training. And the CVS concept is central to this culture. Surgical videos are a useful
educational tool, as simulated decision-making exercises. However, public video platforms
should be used judiciously by trainees, since their content is not peer-reviewed or
quality-controlled.
