Causes and prevention of laparoscopic bile duct injuries: analysis of 252 cases from a human factors and cognitive psychology perspective

Abstract

Objective: To apply human performance concepts in an attempt to understand the causes of and prevent laparoscopic bile duct injury.

Summary background data: Powerful conceptual advances have been made in understanding the nature and limits of human performance. Applying these findings in high-risk activities, such as commercial aviation, has allowed the work environment to be restructured to substantially reduce human error.

Methods: The authors analyzed 252 laparoscopic bile duct injuries according to the principles of the cognitive science of visual perception, judgment, and human error. The injury distribution was class I, 7%; class II, 22%; class III, 61%; and class IV, 10%. The data included operative radiographs, clinical records, and 22 videotapes of original operations.

Results: The primary cause of error in 97% of cases was a visual perceptual illusion. Faults in technical skill were present in only 3% of injuries. Knowledge and judgment errors were contributory but not primary. Sixty-four injuries (25%) were recognized at the index operation; the surgeon identified the problem early enough to limit the injury in only 15 (6%). In class III injuries the common duct, erroneously believed to be the cystic duct, was deliberately cut. This stemmed from an illusion of object form due to a specific uncommon configuration of the structures and the heuristic nature (unconscious assumptions) of human visual perception. The videotapes showed the persuasiveness of the illusion, and many operative reports described the operation as routine. Class II injuries resulted from a dissection too close to the common hepatic duct. Fundamentally an illusion, it was contributed to in some instances by working too deep in the triangle of Calot.

Conclusions: These data show that errors leading to laparoscopic bile duct injuries stem principally from misperception, not errors of skill, knowledge, or judgment. The misperception was so compelling that in most cases the surgeon did not recognize a problem. Even when irregularities were identified, corrective feedback did not occur, which is characteristic of human thinking under firmly held assumptions. These findings illustrate the complexity of human error in surgery while simultaneously providing insights. They demonstrate that automatically attributing technical complications to behavioral factors that rely on the assumption of control is likely to be wrong. Finally, this study shows that there are only a few points within laparoscopic cholecystectomy where the complication-causing errors occur, which suggests that focused training to heighten vigilance might be able to decrease the incidence of bile duct injury.

Figures

Figure 1. Classification of laparoscopic bile duct injuries. The mechanism of the injury is in the text and Table 1. Class III injuries are subdivided according to the location of the proximal line of transection.

Figure 2. Operative cholangiogram demonstrating nonopacification of the hepatic ducts. This was misinterpreted as normal, and a class III injury ensued.

Figure 3. Operative cholangiogram demonstrating narrowing of the common bile duct. The cholangiocatheter is located in the common duct rather than the cystic duct. This patient went on to have a class III injury.

Figure 4. Operative cholangiogram interpreted as normal. The cholangiocatheter is located in the right hepatic duct rather than the cystic duct. This patient had a class IV injury.

Figure 5. Conceptual model of human cognition (adapted from references 5, 20, 21). The decision-making part of the mind is depicted by the four concentric circles in the center. Conscious thought is represented by the innermost three circles, where decisions require varying levels of cognitive energy: schemata or intuitive decisions require the least resources. Accurate intuitive decision-making comes as a result of extensive experience and training. All expertise is largely intuitive. Uneducated intuitive decisions, however, have a low accuracy level. Rule-based thinking invokes learned responses that might not have become intuitive: “turn the wheels in the direction of the skid” is an example. Knowledge-based thinking requires the greatest amount of attention and deliberation (for example, complex decisions involving large amounts of data; creative thinking; etc.). Everything that reaches the conscious mind is first processed in the subconscious, which filters the virtually limitless number of possible thoughts and allows a select few to reach consciousness. Even perceptual information is highly filtered. We are consciously aware at any moment of only a small portion of the images, sounds, tactile and proprioceptive stimuli, and smells that are reaching us. We can selectively focus attention from one to another but not to more than a few at a time. It is impossible, for example, to follow two busy independent audible conversations simultaneously. Perception of events in the operating field might include visual, haptic (see text), or auditory information. Laparoscopic surgery eliminates the very useful haptic input and stereoscopic depth perception. Guidance for the operation relies almost entirely on visual data, so imaging equipment should be of the highest quality.

Figure 6. Kanizsa Triangle. Most people see a bright white triangle occluding an underlying triangle and parts of the three black circles. The white triangle is a creation of visual heuristics.

Figure 7. An illusory dog assembled automatically by subconscious processes.