Choledocholithiasis diagnostics - endoscopic ultrasound or endoscopic retrograde cholangiopancreatography?

It is estimated that 3.4% of patients qualified for cholecystectomy due to cholelithiasis have a coexisting choledocholithiasis. For decades, endoscopic ascending retrograde cholangiopancreatography has been the golden diagnostic standard in cases of suspected choledocholithiasis. The method is associated with a relatively high rate of complications, including acute pancreatitis, the incidence of which is estimated to range between 0.74% and 1.86%. The mechanism of this ERCP-induced complication is not fully understood, although factors increasing the risk of acute pancreatitis, such as sphincter of Oddi dysfunction, previous acute pancreatitis, narrow bile ducts or difficult catheterization of Vater's ampulla are known. It has been suggested to discontinue the diagnostic endoscopic retrograde ascending cholangiopancreatography and replace it with endoscopic ultrasonography due to possible and potentially dangerous complications. Endoscopic ultrasonography has sensitivity of 94% and specificity of 95% regardless of gallstone diameter, as opposed to magnetic resonance cholangiography. However, both of these parameters depend on the experience of the performing physician. The use of endoscopic ultrasonography allows to limit the number of performed endoscopic retrograde cholangiopancreatography procedures by more than 2/3. Ascending endoscopic retrograde cholangiopancreatography combined with an endoscopic incision into the Vater's ampulla followed by a mechanical evacuation of stone deposits from the ducts still remains a golden standard in the treatment of choledocholithiasis. Despite some limitations such as potentially increased treatment costs as well as the necessity of the procedure to be performed by a surgeon experienced in both endoscopic retrograde cholangiopancreatography as well as endoscopic ultrasonography, the diagnostic endoscopic ultrasonography followed by a simultaneous endoscopic retrograde cholangiopancreatography aimed at gallstone removal is the most efficient diagnostic and therapeutic management scheme in cases of suspected choledocholithiasis.

Cholelithiasis represents a common condition affecting 10–20% of European population(. Among this group, gallstone deposits present in the common bile duct occur in 15–20% of patients. It is estimated that 3.4% of patients qualified for cholecystectomy due to cholelithiasis have a coexisting choledocholithiasis(.

The aim of the study is to present the current views on the optimal diagnostic method for choledocholithiasis.

As opposed to cholelithiasis, in the case of which laparoscopic cholecystectomy is the golden standard treatment, optimal diagnostics and treatment of post-cholecystectomy choledocholithiasis or choledocholithiasis coexisting with cholelithiasis is still under debate. Surgical opening of the common bile duct followed by gallstone removal represents the oldest method, which today is used only exceptionally and in special cases.

Endoscopic retrograde cholangiopancreatography (ERCP) has become a milestone in the imaging of biliary and pancreatic ducts. The first diagnostic endoscopic retrograde cholangiopancreatography was performed in 1968(, while its therapeutic variation combined with the incision of Vater's ampulla was first performed in 1974(.

During this period, the range of procedures complementing the diagnostic ERCP has also increased significantly. All these procedures are preceded by an endoscopic incision of Vater's ampulla (its biliary or pancreatic part) or by a balloon dilatation of the ampulla. Thus obtained access to the common bile duct or the pancreatic duct allows to perform a range of other treatment techiques within the biliary ducts and the duct of Wirsung, including stenosis correction, gallstone crushing and removal as well as stenting of stenosis.

Over the years, the ERCP has been considered a “golden standard” in the imaging of biliary ducts in patients suspected of choledocholithiasis, although the method allows to diagnose choledocholithiasis in only 50% of patients from non-selected groups(. It ought to be noted that the ERCP is an invasive procedure, associated with the risk of complications. Unfortunately, published literature reports distinguishing between post-diagnostic ERCP complications and complications following the ERCP combined with the incision of Vater's ampulla are sparse. In practice, the diagnostic ERCP may be associated with complications such as acute pancreatitis, purulent inflammation of the bile ducts or acute cholecystitis(. However, acute pancreatitis is the most common and the most dangerous complication of diagnostic ERCP. A multicenter study by Loperfido( estimated the incidence of acute pancreatitis to be 0.74% following diagnostic ERCPs and 1.4% following therapeutic ERCPs. A large multicenter study by Masci et al.(, which involved American centers, evaluated the overall complications following 782 diagnostic ERCP and 1,662 combined ERCP and sphincterotomy procedures. Acute pancreatitis occurred in 1.6% of patients after diagnostic ERCPs and in 1.86% of patients after therapeutic ERCPs.

The mechanism of ERCP-induced acute pancreatitis is not fully understood, although many factors increasing the risk of this complication have been identified.

The major ones include(:

Suspected sphincter of Oddi dysfunction;

Previous acute pancreatitis;

Normal bilirubin serum levels prior to ERCP;

Normal image of bile ducts at ERCP;

Difficult catheterization of Vater's ampulla;

Sex: female.

The frequency of diagnostic ERCPs has decreased since the introduction of alternative diagnostic methods for bile duct disorders, such as magnetic resonance cholangiopancreatography (MRCP) and endoscopic ultrasonography. However, a number of physicians forget that the ERCP is the most dangerous diagnostic procedure associated with the highest number of complications, including life-threatening ones(.

According to the 2008 recommendations of the British Society of Gastroenterology(, patients suspected of choledocholithiasis should be diagnosed based on non-invasive endoscopic ultrasonography (EUS) (fig. 1). Despite high ERCP sensitivity (90%) and specificity (98%) (, negative results are obtained in 27–67% of ERCP procedures performed due to suspected choledocholithiasis(. Similar recommendations are also formulated by other authors. Baron et al.( believe that discontinuation of diagnostic ascending retrograde cholangiopancreatography following ERCP is the most efficient prophylactic method in acute pancreatitis.

Fig. 1

A stone in the common bile duct

Endoscopic ultrasonography of bilia r y duct s performed at a frequency of 7.5 and 12 Mhz is the best alternative which, most importantly, is virtually free of complications. An extensive metaanalysis involving 2,673 patients( showed that endoscopic ultrasonography has sensitivity of 94% and specificity of 95%. At the same time, considering modern endosonographic resolution (0.1 mm), authors believe that this method is a new golden standard in bile duct diagnostics. The data from the metaanalysis do not allow to determine whether endo-ultrasonographic sensitivity and specificity are dependent on the size of gallstone deposits. However, according to two other authors(, endo-ultrasonographic sensitivity and specificity are independent of the size of deposits, as opposed to MRCP and ERCP, which both of theme sensitivity and specificity decrease with the size of stones in the ducts in a non-linear manner.

The increasing use of endoscopic ultrasonography in choledocholithiasis diagnostics provoked a discussion on the optimal diagnostic and therapeutic scheme. In the era when ERCP was the primary diagnostic procedure, in the case of confirmed presence of gallstone deposits, the diagnostic procedure was simultaneously converted into a therapeutic procedure by performing an incision of Vater's ampulla and removing the stones. Endoscopic ultrasonography is used only for diagnostic purposes. A question therefore arises, once gallstone deposit is identified by endoscopic ultrasonography, whether the ERCP should be performed simultaneously or whether the endoscopic stone removal should be postponed and performed as a separate procedure.

Most authors( believe that a simultaneous therapeutic ERCP with gallstone removal following endosonographic identification of deposits in the ducts is the optimal diagnostic and therapeutic strategy in patients with choledocholithiasis. A systematic publication review performed by Petrov and Savides( included 191 published prospective studies on choledocholithiasis diagnostics and treatment in a group of 2,500 patients. It was shown that, in the case of confirmed cholelithiasis, endoscopic ultrasonography combined with therapeutic ERCP is an optimal diagnostic and therapeutic scheme for suspected choledocholithiasis.

Although the scheme allows to avoid the unnecessary ERCP in 67.1% of patients and thus significantly reduce the rate of complications, it also has some limitations. The endoscopist performing the endosonographic procedure may sometimes lack experience in the therapeutic ERCP. The method may be regarded in some clinics as more expensive compared to the diagnostic and therapeutic scheme based solely on the ERCP(. Furthermore, it is estimated that( a spontaneous passage of stones into the duodenum occurs in 1/3 of patients diagnosed with choledocholithiasis.

It seems, despite the above observations, that the replacement of diagnostic ERCP with endoscopic ultrasonography combined with a complementary therapeutic ERCP should become the golden standard in the diagnostics and treatment in patients suspected of choledocholithiasis.