Critical View Of Safety
“The concept of the critical view was described in 1992 but the term CVS was introduced in 1995 in an analytical review of the emerging problem of biliary injury in laparoscopic cholecystectomy. CVS was conceived not as a way to do laparoscopic cholecystectomy but as a way to avoid biliary injury. To achieve this, what was needed was a secure method of identifying the two tubular structures that are divided in a cholecystectomy, i.e., the cystic duct and the cystic artery. CVS is an adoption of a technique of secure identification in open cholecystectomy in which both cystic structures are putatively identified after which the gallbladder is taken off the cystic plate so that it is hanging free and just attached by the two cystic structures. In laparoscopic surgery complete separation of the body of the gallbladder from the cystic plate makes clipping of the cystic structures difficult so for laparoscopy the requirement was that only the lower part of the gallbladder (about one-third) had to be separated from the cystic plate. The other two requirements are that the hepatocystic triangle is cleared of fat and fibrous tissue and that there are two and only two structures attached to the gallbladder and the latter requirements were the same as in the open technique. Not until all three elements of CVS are attained may the cystic structures be clipped and divided. Intraoperatively CVS should be confirmed in a “time-out” in which the 3 elements of CVS are demonstrated. Note again that CVS is not a method of dissection but a method of target identification akin to concepts used in safe hunting procedures. Several years after the CVS was introduced there did not seem to be a lessening of biliary injuries.
Operative notes of biliary injuries were collected and studied in an attempt to determine if CVS was failing to prevent injury. We 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. This seemed to occur most frequently under conditions of severe acute or chronic inflammation. 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 conditions a compelling visual deception that the common bile duct is the cystic duct may occur. CVS is much less susceptible to this deception because more exposure is needed to achieve CVS, and either the CVS is attained, by which time the anatomic situation is clarified, or operative conditions prevent attainment of CVS and one of several important “bail-out” strategies is used thus avoiding bile duct injury.
CVS must be considered as part of an overall schema of a culture of safety in cholecystectomy. When CVS cannot be attained there are several bailout strategies such a cholecystostomy or in the case of very severe inflammation discontinuation of the procedure and referral to a tertiary center for care. The most satisfactory bailout procedure is subtotal cholecystectomy of which there are two kinds. Subtotal fenestrating cholecystectomy removes the free wall of the gallbladder and ablates the mucosa but does not close the gallbladder remnant. Subtotal reconstituting cholecystectomy closes the gallbladder making a new smaller gallbladder. Such a gallbladder remnant is undesirable since it may become the site of new gallstone formation and recurrent symptoms . Both types may be done laparoscopically.”
Strasberg SM, Hertl M, Soper NJ. An analysis of the problem of biliary injury during laparoscopic cholecystectomy. J Am Coll Surg 1995;180:101-25.
First described by Pablo Mirizzi in 1948 as “functional hepatic syndrome”, Mirizzi’s syndrome was initially thought to be the result of a “physiologic sphincter” of the hepatic duct. It is now understood to be a result of mechanical obstruction of the common hepatic duct secondary to an impacted stone in the gallbladder neck, Hartmann’s pouch, or the cystic duct. The syndrome is very uncommon in Western populations with a reported prevalence of 0.05%-5.7% in large modern series of patients undergoing biliary surgery. With chronic stone impaction, inflammation and recurrent cholangitis can develop with subsequent erosion into the common bile duct (CBD) and resultant biliobiliary fistula between the gallbladder and CBD.
The syndrome encompasses a spectrum of disease. Broadly speaking, Mirizzi’s syndrome can be grouped into two major categories: (1) external compression of the CBD without a fistula (Type 1), and (2) erosion into the CBD causing a cholecystobiliary fistula (Type II-IV). Csendes classification is currently being used to reflect the above classification. Retrospective studies have identified an association between Mirizzi’s syndrome and gallbladder cancer, with an incidence as high as 28%, relative to an incidence of 1-2% in patients with uncomplicated gallstone disease. As with other malignant processes of the biliary tract, biliary stasis and chronic inflammation have been suggested to play a role. In general, it is difficult to distinguish benign Mirizzi’s syndrome from a neoplastic process preoperatively, although older patient age, significantly elevated Ca 19-9, and imaging features suggestive of invasion into the liver or a mass filling the gallbladder should raise suspicion for malignancy.
The most common presenting symptoms are right upper quadrant pain, jaundice, nausea/vomiting, and fever. This spectrum of findings overlaps with several other pathologic processes of the hepatobiliary tract, making preoperative diagnosis difficult. Additionally, the clinical picture may be complicated by the concurrent presence of acute cholecystitis, pancreatitis, or even gallstone ileus. Mirizzi’s syndrome should be suspected in any patient presenting with right upper quadrant pain and abnormal liver enzymes (particularly elevated bilirubin and alkaline phosphatase) or imaging suggestive of an impacted stone. Three findings on imaging together suggest a diagnosis of Mirizzi’s: 1) dilation of the biliary system above the level of the gallbladder neck, 2) the presence of a stone impacted in the gallbladder neck, and 3) an abrupt change to a normal width of the common duct below the level of the stone. Such findings should prompt further imaging to better define the biliary tree, either indirectly though magnetic resonance cholangiopancreatography (MRCP), or directly through endoscopic retrograde cholangiopancreatography (ERCP) or percutaneous transhepatic cholangiography (PTC). No imaging modality is entirely sensitive for Mirizzi’s syndrome and the key is to maintain a high index of suspicion.
Management of Mirizzi’s syndrome depends on the degree of fistula. In Type I disease, laparoscopic cholecystectomy is usually achievable, either total (classic) or subtotal, depending on the specific intraoperative findings. If the view of safety can be attained with the critical structures isolated, a classic cholecystectomy may be performed. If the view of safety cannot be achieved due to inflammation or adhesions, the gallbladder is taken down retrograde and opened near the cystic duct orifice. All stones are removed, including any impacted stones, and the cystic duct orifice is examined for the presence of bile to determine whether it is patent. If the cystic duct is patent, it should be ligated (if possible), or the remnant gallbladder should be sutured closed over it (choledochoplasty). An external closed suction drain may be left in the gallbladder fossa and removed the following day if drainage is non-bilious. More commonly, the cystic duct is obliterated, and a subtotal cholecystectomy with removal of all stones is sufficient.
Management of Mirizzi’s syndrome in the presence of a biliobiliary fistula is more complex. If the fistula involves <1/3 of the CBD circumference (Type II), options include primary repair using absorbable suture, closure over a T-tube, or choledochoplasty using the remnant gallbladder. The last approach is preferable to maintain the diameter of the CBD and minimize the risk of subsequent stricture but requires that sufficient gallbladder remnant be available to allow closure. In the presence of a more extensive fistula (Type III or IV), bilioenteric anastomosis is usually the best option.