The Critical View of Safety: Why It Is Not the Only Method of Ductal Identification Within the Standard of Care in Laparoscopic Cholecystectomy.

Abstract

Laparoscopic cholecystectomy was introduced into wide practice about 1990, with demonstrated benefit to patients. However, it was associated with a sharp increase in major bile duct injuries. Biliary injuries are morbid, costly, and the source of litigation. Although not usually due to negligence, they are iatrogenic and detract from the value of laparoscopic cholecystectomy. Most major bile duct injuries are due to misidentification. In the “classical injury,” the common bile duct is thought to be the cystic duct and is divided. Aberrant hepatic ducts may also be mistakenly identified as the cystic duct or cystic artery. The Critical View of Safety (CVS) is a method of target identification, the targets being the cystic duct and the cystic artery. Today, CVS is taught and used widely. It is accepted as a good means of identification of the cystic structures and its use is within the standard of care. The purpose of this surgical perspective is to examine whether CVS has reached the status of being the only acceptable method for identification of structures in laparoscopic cholecystectomy. HISTORY OF THE CRITICAL VIEW OF SAFETY The term “Critical View of Safety” was introduced in an analytical review written in response to the sudden increase in biliary injury associated with laparoscopic cholecystectomy.1 CVS is a re-working of a method of secure identification in open cholecystectomy in which the cystic duct and artery are putatively identified, after which the gallbladder is taken off the cystic plate so that the gallbladder is attached only by the 2 cystic structures.2 Only then is secure target identification achieved. In laparoscopic surgery, complete separation of the gallbladder from the cystic plate makes clipping of the cystic structures difficult, so this step was modified to require only that the lower part of the gallbladder (about one-third) be separated from the cystic plate. The other requirements, that is, that the hepatocystic triangle be cleared of fat and fibrous tissue and that 2 and only 2 structures remain attached to the gallbladder, are the same as in the open technique. Intraoperatively, CVS should be confirmed in a “time-out” in which the 3 elements of CVS are demonstrated. After the introduction of CVS in1995, operative notes were studied in an attempt to determine if CVS was used in procedures in which biliary injury had occurred.3 It was found that the method of target identification that was failing was not CVS, but the infundibular technique in which the cystic duct is identified by exposing the funnel shape where the infundibulum of the gallbladder joins the cystic duct. Inflammatory fusion and contraction may cause juxtaposition or adherence of the common hepatic duct to the side of the gallbladder. When the infundibular technique of identification is used under these circumstances, a compelling visual deception may result that the common bile duct is the cystic duct.3 CVS is less susceptible to this deception because more exposure of structures is needed to achieve CVS. Either the CVS is attained, by which time the anatomic situation is usually clarified, or operative conditions such as severe acute or chronic inflammation prevent attainment of the CVS. In the latter case, when the CVS cannot be reached, 1 of several important “bail-out” strategies such as subtotal fenestrating cholecystectomy4 can be employed, thus avoiding bile duct injury. Of course, the CVS should not be seen in isolation, but as an element of an overall schema of a “Culture of Safety in Cholecystectomy” in which other elements such as good bail-out techniques, good access techniques, and other elements of safety are also employed. EFFECTIVENESS OF THE CRITICAL VIEW OF SAFETY There are 2 principal lines of evidence that the CVS is an effective method of target identification. First, there are several reports containing several thousand patients in which CVS was used for target identification without a biliary injury due to misidentification,5,6 whereas, based on an incidence of biliary injury of 3 to 4/1000 cases, about 20 biliary injuries would be expected. Secondly, in studies that have examined the mechanisms of major biliary injury, CVS has rarely been described as the method of target identification.7,8 Taken as a group, these studies are highly supportive of the value of CVS, but from the perspective of evidence-based medicine, they are at a low level of evidence. So, why after 25 years has there not been a randomized trial that compares methods of target identification? The answer lies in the fact that although many major biliary injuries still occur, that is, 2000 to 3000 per year in the USA, the event rate is only about 3 per 1000 cholecystectomies (up from about 1 per 1000 in the era of open cholecystectomy). A randomized trial cannot practically be performed because the event rate is so low that about 4500 patients per arm would be required. Despite the low event rate, biliary injuries are not uncommon because of the huge number of cholecystectomies performed annually—about 800,000 in the USA. Thus, biliary injury has aspects of a rare disease and a common disease. There are also important corollaries. Case series of laparoscopic cholecystectomies are almost always too small to provide insights into the causes of biliary injury. Population studies of thousands of patients are required to have enough events to gain meaningful insights. That is why going back almost 100 years,9 much of what is known about biliary injury has been gleaned not from case series of cholecystectomies, but from case series of the injuries themselves. WHAT CONSTITUTES STANDARD OF CARE? “Standard of care” is the legal term for the duty owed by one person to another and applies to both nonmedical and medical situations (such as driving a car). It is the amount of care that a reasonable person would take to prevent injury to another person. In the medical-legal context, a doctor must use the amount of skill, learning, and care ordinarily used by members of his/her profession in similar circumstances. Whether a given treatment or procedure is acceptably within the standard of care depends on whether it falls within the norms of practice, which are established by professional authorities in writings and recorded electronic communications. In recent years, the evidence presented in these communications has been graded from 1 to 5, with randomized trials being at a very high level, whereas case series and expert opinion are considered weaker evidences. Often several ways of diagnosis or treatment fall within the standard of care. Consensus conferences which weigh the available evidence regarding a type of care may sometimes conclude that there is high level evidence that one particular type of care is superior to all others. That type of conclusion, if based on high levels of evidence, could establish that failure to use a specific type of care in a particular situation will most likely be below the standard. An obvious example would be the failure to use antibiotics in an acute bacterial infection such as cellulitis. Finally, in determining standard of care, an important criterion is whether a type of care is in broad use by qualified surgeons. If it is, even by a moderate percentage of surgeons, then there is a strong argument that it falls within the standard of care. IS THE CRITICAL VIEW OF SAFETY THE ONLY ACCEPTABLE MEANS OF DUCTAL IDENTIFICATION DURING LAPAROSCOPIC CHOLECYSTECTOMY? Critical View of Safety, routine cholangiography, the infundibular technique, visualization of the common bile duct and common hepatic duct, and top-down cholecystectomy are some methods that have been advocated for target identification in cholecystectomy. CVS is not the only method within the standard of care for the following reasons. Textbooks of surgery may10 or may not11 recommend CVS as the method of target identification. The evidence that CVS is superior to all other methods is level 4, that is, case series. No consensus conference has published a guideline that CVS is the only effective method of target identification. Many surgeons in current practice use and are confident in other methods.12 The fact that some experts believe that CVS is the preferred method of target identification in laparoscopic cholecystectomy is insufficient alone to establish it as the only method within the standard of care. Stated otherwise, at this time, CVS is not the only method of ductal identification within the standard of care. PROBLEMS WITH CVS Dissemination of new information is a difficult problem in surgery. Even after more than 20 years, surgeons often have a poor understanding of the criteria for CVS, and may confuse CVS with the infundibular technique.12,13 Reluctance to adopt new techniques or methods can also be a challenge. In the case of CVS, this is compounded by the low event rate of biliary injury, which makes an error trap like the infundibular technique even harder to overcome. If it fails only 1 in 300 times, then it works 299 out of 300 times and there is a huge reservoir of confidence in it.13 Also, the infundibular method is easier and takes less dissection than CVS. Attainment of the CVS is not usually recorded or documented photographically, and although the dictated operative note may state that the CVS was achieved, recent evidence suggests this is frequently not the case.7 FUTURE OF CVS Critical View of Safety is part of the Culture of Safety In Cholecystectomy (COSIC) and this problem has been taken up by SAGES in a novel effort called “Safe Cholecystectomy” (www.sages.org/safe-cholecystectomy-program) The SAGES Safe Cholecystectomy program aims to better disseminate understanding and use of CVS and other strategies for prevention of biliary injury such as use of intraoperative imaging and approaches to the difficult gallbladder that include proper bail-out techniques.4 A multisociety consensus development conference is planned in 2017 on the subject of bile duct injury to study and promote safety in cholecystectomy. The role and application of CVS and other strategies for prevention of biliary injury will be critically examined in that forum. An effective and easy method of photodocumentation of CVS is now available for surgeons who wish to record CVS visually.14 For those who wish to record it in operative notes, it is important to know that CVS cannot be said to have been achieved without attainment of all 3 elements of this method of target identification. We dictate these 3 elements into operative notes and recommend it as an excellent practice. ACKNOWLEDGMENT The authors thank Ms Christine A. Vaporean of the law firm of Brown and James, Saint Louis, Missouri, for helpful discussions and suggestions.