LAUSR

In this very interesting study, the authors compared the diagnostic accuracy of ultrasonography (US) with magnetic resonance cholangiopancreatography (MRCP) for the evaluation of choledocholithiasis. The authors retrospectively selected 243 patients suspected for choledocholithiasis who underwent both US and MRCP within 1 month, then they compared common bile duct measurements, false positive and false negative percentages in common bile duct stone detection. The authors concluded that US is ideal as the first step in the diagnostic algorithm for choledocholithiasis. Diagnostic accuracy was high, in line with previously published paper (AUC = 0.727; 95% CI, 0.603–0.852). However, due to the high percentage of false negatives (16%), if patients have elevated liver enzymes or a high risk of CBD stones, MRCP is recommended. This paper underlines the role of US as first step in patients with suspected biliary stones, strengthen its importance in this clinical scenario. On the other hand, the role of MRCP deserves a more comprehensive evaluation. Population data reveal that 10% of American adults will develop symptomatic gallstones over the course of a decade, estimating an annual cost close to 6 billion of dollar. In this setting, choosing the right diagnostic test is extremely important. Due to the large number of patients with suspected biliary stones, ultrasonographic evaluation of biliary three as first step is considered a stronghold. Transabdominal US represents the first line, non-expensive, noninvasive imaging examination performed for any sign/symptom/condition possibly referring to liver disease. It is considered the best examination to study gallbladder stones due to the small distance from the abdominal wall and the absence of interposed gas, with a sensitivity close to 96%. Unfortunately, stones within the common bile duct are very difficult to detect using ultrasound. CBDS often do not show acoustic shadowing or are within the intrapancreatic part of common bile duct, where there are more artifacts related to intestinal gas. In those cases, diagnostic accuracy drops to less than 50%. In order to improve the diagnosis, indirect signs of choledocholithiasis should be considered. First, CBD dilatation suggests biliary stones in the common bile duct, even if the definition of CBD dilation is controversial, considering that the “normal” caliber can ranges from 5 to 11 mm according to age or previous cholecystectomy. Second, the size and number of gallbladder stones, as multiple, small-sized gallstones are more likely to migrate. Despite these limitations, the clinical value of US as first step imaging modality is not questionable, considering that it contributes to define the risk of patients to have CBDS. As a matter of fact, according to the ASGE guidelines, positive findings of common bile duct stone on US is considered one of the main high-risk criteria for choledocholithiasis, which should directly prompt ERCP. The most relevant question at this point is how to further investigate patients with negative or doubtful findings of choledocholithiasis, considering demographic characteristics of biliary stones, patient's preference, costs, machines availability, data on diagnostic accuracy for different imaging methods, and complication related to Endoscopic Ultrasound (EUS) or Endoscopic Retrograde Cholangiopancreatography (ERCP). ERCP-guided treatment of bile duct stones is now considered a minimally invasive procedure, performed mainly for interventional purpose. Despite the large number of technical improvements over the past decade, the risk of major adverse events is still high (6%–15%). This has underlined the need to identify the appropriate candidates and to reserve biliary endoscopy for patients who have the highest probability of intraductal stones. How to define these patients is still been debated. In the most extensive modeling study assessing the role of choledocholithiasis, appears that EUS and MRCP result in cost-saving by avoiding the expense and adverse events of ERCP. Guidelines from the American Society for Gastrointestinal Endoscopy (ASGE), recommends, in patients with intermediate risk (10%–50%) of choledocholithiasis, either EUS or MRCP to confirm the diagnosis. The evidence for EUS versus MRCP comes from a recently published meta-analysis by Meeralam and colleagues. Authors reported comparable accuracy between the two methods, with high specificity for both (EUS = 0.90 [95% CI, 0.83–0.94], I2 Z 54.2%, MRCP = 0.92 [95% CI, 0.87–0.96], I2 Z 68.8%, P Z 0.42), and slightly higher pooled sensitivity for EUS (EUS = 0.97 [95% confidence interval (CI), 0.91– 0.99], I2 Z 15.1%; MRCP = 0.87 [95% CI, 0.80–0.93], I2 Z 55.5, P Z 0.006). Another relevant Chocrane Systematic review from Giljaca Received: 21 December 2021 Revised: 28 December 2021 Accepted: 28 December 2021