Causes and Prevention of Laparoscopic Bile Duct Injuries
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.
Bile duct injuries are the main serious technical complication of laparoscopic cholecystectomy.1,2 Data are insufficient to determine precisely the frequency of bile duct injuries, but a reasonable estimate is one in 1,000 cases.2 A decade ago, as the technique of laparoscopic cholecystectomy was first being learned by otherwise fully trained, practicing surgeons, the injury rate was noted to be greater during an individual’s first dozen cases than in subsequent ones.2 This learning curve contribution is now much less important, for surgical residents learn the procedure under direct supervision of more experienced surgeons.
Surgeons have always analyzed their technical complications for insights that might be translated into improved performance. In the past the information available from such reviews could rarely go much beyond a tabulation of results. An understanding of the root causes of technical complications remained elusive. This report takes analysis of technical complications to greater depths, for it integrates the findings of videotapes of operations involving bile duct injuries, operative notes dictated after the operation had been completed but before an injury had become apparent, and conceptual tools of human factors research and the cognitive science of human error.
The operations of 252 patients who had major bile duct injuries during laparoscopic cholecystectomy were analyzed. The patients had been referred to the authors for evaluation or treatment, and the accompanying records were complete with respect to operative notes from the initial operation and any subsequent operations done to repair the injury. The injuries involved the common bile duct (CBD), common hepatic duct (CHD), lobar hepatic ducts, or segmental hepatic ducts. Bile leaks from the gallbladder bed and cystic duct were excluded. Operative notes, pathology reports, radiology reports, operative x-rays, postoperative x-rays, and 22 unedited videotapes of laparoscopic cholecystectomies that involved bile duct injuries were analyzed to determine the causes of the injuries and circumstances contributing to them.
Seventy-seven percent of patients were women and 23% were men. The average age was 46 years (range 19 – 86 years). The indications for the operation (i.e., the diagnoses) were chronic cholecystitis, 69%; acute cholecystitis, 29%; gallstone pancreatitis, 2%; and cholangitis, 0.4%.
The injuries were examined within the framework of human error analysis. The surgeon’s performance was analyzed for: 1) perceptual input data (visual and/or haptic), 2) knowledge and decision-making, and 3) action (i.e., skill, the quality of the technical aspects of the operation). Data from imaging reports (operative and postoperative), reparative operations, and videotapes were analyzed and compared with the original operative reports to determine the cause of the injury and the working assumptions of the surgeon.
The following criteria were employed when categorizing the errors. We considered misperception to have occurred in instances where the data showed that 1) the surgeon had seen and deliberately cut a duct that he or she thought at that moment was a different duct (e.g., the surgeon cut the CBD thinking it was the cystic duct), or 2) the surgeon injured an unseen duct while performing a dissection that he or she believed was a safe distance from the duct (e.g., a scenario characteristic of class II injuries). The error was considered to represent faulty decision-making or a knowledge error if the data indicated that 1) the surgeon had departed from the orthodox operative strategy for performing a laparoscopic cholecystomy, or 2) had performed the operation in a setting where laparoscopic cholecystectomy was inappropriate. We considered that the fault was at the action or skill level when there was evidence that the dissection was performed in a clumsy way; when an identified duct being cleared of connective tissue was accidentally cut or cauterized. In the discussion section we have interpreted the findings according to accepted principles of cognitive psychology and human error. Although some of these ideas may be new to surgeons, we are unable to argue their validity within the context of this paper. Instead, we have cited representative literature that will allow the reader to determine for himself or herself the strength of their foundations.
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