Critical view of safety

Laparoscopic cholecystectomy (LC) is the gold standard technique for the treatment of gallstones and cholecystitis. Since its introduction in the ‘90s, a higher rate of biliary duct injury (BDI) has been described compared to open cholecystectomy. This difference is maintained even beyond the learning curve. More complicated and more proximal injuries are found in the laparoscopic technique. Recent studies including over 700,000 cholecystectomies have reported a 0.22% of BDI. In other series it has been described as 0.4% of procedures. It is associated with a higher perioperative morbidity and mortality rate, and it usually requires surgical repair in specialized centers. Despite the low rate of BDI, laparoscopic cholecystectomy is a very common procedure and a high number of patients can be affected. Many factors have been described as associated with BDI. Obesity, advanced age, male sex, adhesions, severe local inflammation, aberrant anatomy, hemorrhage or surgeon’s experience are some of them. Many classifications of BDI have been described. Bismuth et al categorized lesions according to their anatomic location, from type 1 to type 5. Strasberg et al established a new classification of the most common laparoscopic injuries, including leaks, partial transections and complete occlusions, apart from strictures. Variations on this classification, with more detailed subcategories, have been described since then. More recent classifications include vascular injuries, such as the Stewart-Way and the Hanover systems. The most common cause of BDI is misidentification of bile structures. The aberrant low lying right bile duct is the most important anomaly while performing a cholecystectomy according to Strasberg. Other causes are slippage of clips on the cystic duct, inadvertent thermal injury to the common bile duct (CBD) or tenting of the CBD. Inflammation can result in changes in usual anatomy, hiding the CD or changing the location of Hartmann’s pouch. Aberrant ducts can be found during the dissection. Therefore surgical technique should be perfected in order to reduce BDI, dividing small pieces of tissue at the same time while dissecting. Early diagnosis and intraoperative early repair, by an hepatobiliary surgeon if possible, is preferred if the patient is stable and the infection is under control. Delayed operative repair is performed in the other cases. Endoscopic treatment and percutaneous stenting are also therapeutic options. Nevertheless, the best treatment of BDI is prevention. Four methods for the identification of the cystic structures during LC have been described: routine intraoperative cholangiography, critical view technique, infundibular technique, and dissection of the main bile duct with visualization of the cystic duct (CD) or CBD insertion. In the critical view technique, described as a method for target identification by Strasberg et al in 1995 and adopted by several international societies as the safest method, the CD and cystic artery are identified through dissection of the upper border of the Calot triangle along the underside of the gallbladder. Cephalad traction of the fundus and lateral traction of the infundibulum are needed. Dissection continues until only 2 structures are seen entering the gallbladder. It is important not to have a preconception of where the structures lie. The criteria to achieve the critical view of safety (CVS) are: Calot’s hepatocystic triangle dissection, visualization of the liver after dissecting the lower part of the gallbladder, and visualization of only 2 tubular structures. The common duct need not be seen. Different kinds of dissection technique can be used in order to achieve CVS, such as coagulation, separation, or peeling by dissector. The use of CVS is associated with lower BDI rates. Protocols on the application of the CVS technique differ widely among hospitals. Usually there is no graphic evidence of the achievement of CVS. Several studies have suggested that education on CVS and strict video or photographic documentation should be used to increase the impact of CVS on the BDI rate. A recent anonymous survey among more than 2000 surgeons worldwide surprisingly reported that 78% of them did not properly recognize the CVS criteria, and a higher rate of BDI was found among surgeons who incorrectly identified the elements of the CVS. Many surgeons think that the infundibular technique is the CVS technique, leading to a pseudo CVS technique. This knowledge is more frequent among younger surgeons in academic settings. A prospective study of photographic documentation of CVS during LC showed an adequate CVS established by two different observers in 45-52% of the cases. This indicated that audits on correct technique and scoring systems could improve BDI rates. Some studies suggest that the operative time might be significantly reduced when the LC is performed under the CVS protocolized technique. Gallstones are typically a benign condition, and an unacceptable risk of BDI should not be taken by the surgeon. The stopping rules on LC should be taken into account by the surgeon when CVS is not achieved. Conversion to open procedure, partial cholecystectomy (fenestrating cholecystectomy), consulting with more expert faculty, or even aborting the procedure and placing a cholecystostomy tube are options that can reduce the risk of BDI. Avoiding a very difficult cholecystectomy is also a good strategy; signs of advanced and chronic cholecystitis should be detected prior to surgical indication. Intra-operative time-out during LC prior to clipping, cutting or transecting any ductal structures should be established when the CVS criteria have been met. Conclusion: BDIs are more common and complex in LC than in the open technique. The surgeon’s knowledge and skills are important factors to avoid these injuries. Knowing the risk factors and achieving the critical view of safety is mandatory to perform a correct technique, which also includes bail-out strategies in difficult cholecystectomies.