Abstract: We identified five studies including 318 participants (180 participants with and 138 participants without common bile duct stones) that reported the diagnostic accuracy of ERCP and five studies including 654 participants (125 participants with and 529 participants without common bile duct stones) that reported the diagnostic accuracy of IOC. Most studies included people with symptoms (participants with jaundice or pancreatitis) suspected of having common bile duct stones based on blood tests, ultrasound, or both, prior to the performance of ERCP or IOC. Most studies included participants who had not previously undergone removal of the gallbladder (cholecystectomy). None of the included studies was of high methodological quality as evaluated by the QUADAS-2 tool (quality assessment tool for diagnostic accuracy studies). The sensitivities of ERCP ranged between 0.67 and 0.94 and the specificities ranged between 0.92 and 1.00. For ERCP, the summary sensitivity was 0.83 (95% confidence interval (CI) 0.72 to 0.90) and specificity was 0.99 (95% CI 0.94 to 1.00). The sensitivities of IOC ranged between 0.75 and 1.00 and the specificities ranged between 0.96 and 1.00. For IOC, the summary sensitivity was 0.99 (95% CI 0.83 to 1.00) and specificity was 0.99 (95% CI 0.95 to 1.00). For ERCP, at the median pre-test probability of common bile duct stones of 0.35 estimated from the included studies (i.e., 35% of people suspected of having common bile duct stones were confirmed to have gallstones by the reference standard), the post-test probabilities associated with positive test results was 0.97 (95% CI 0.88 to 0.99) and negative test results was 0.09 (95% CI 0.05 to 0.14). For IOC, at the median pre-test probability of common bile duct stones of 0.35, the post-test probabilities associated with positive test results was 0.98 (95% CI 0.85 to 1.00) and negative test results was 0.01 (95% CI 0.00 to 0.10). There was weak evidence of a difference in sensitivity (P value = 0.05) with IOC showing higher sensitivity than ERCP. There was no evidence of a difference in specificity (P value = 0.7) with both tests having similar specificity. Although the sensitivity of IOC appeared to be better than that of ERCP, this finding may be unreliable because none of the studies compared both tests in the same study populations and most of the studies were methodologically flawed. It appears that both tests were fairly accurate in guiding further invasive treatment as most people diagnosed with common bile duct stones by these tests had common bile duct stones. Some people may have common bile duct stones in spite of having a negative ERCP or IOC result. Such people may have to be re-tested if the clinical suspicion of common bile duct stones is very high because of their symptoms or persistently abnormal liver function tests. However, the results should be interpreted with caution given the limited quantity and quality of the evidence.

Plain-language summary: We identified five studies including 318 participants that reported the diagnostic test accuracy of ERCP and five studies including 654 participants that reported the diagnostic test accuracy of IOC. Most studies included people with symptoms (participants with jaundice or pancreatitis) who were suspected of having CBD stones based on blood tests, ultrasound (use of sound waves higher than audible range to differentiate tissues based on how they reflect the sound waves), or both, prior to the having ERCP or IOC. Most studies included participants who had not previously undergone cholecystectomy. Given an average sensitivity of 83% for ERCP, we would expect that on average 83 out of 100 people (this may vary between 72 and 90 out of 100 people) with CBD stones would be detected while the remaining 17 people would be missed and would not receive appropriate treatment. Based on an average specificity of 99% for ERCP, we would expect that on average 99 out of 100 people without CBD stones would be identified as not having CBD stones; 1 out of 100 (this could vary between 0 and 17 out of 100 people) would be false positive and would not receive appropriate treatment. For IOC, an average sensitivity of 99% means that on average 99 out of 100 people (this may vary between 83 and 100 out of 100 people) with CBD stones would be detected while only one person would be missed and would not receive appropriate treatment. In terms of specificity, an average of 99% for IOC means that 99 out of 100 people without CBD stones would be identified as not having CBD stones with only one false positive (this could vary between 0 and 5 out of 100 people) who would not receive appropriate treatment. It appears that both tests are fairly accurate in guiding further invasive treatment as most people diagnosed with CBD stones by these tests have CBD stones. However, some people may have CBD stones in spite of having a negative ERCP or IOC test result. Such people may have to be re-tested if the clinical suspicion of CBD stones is very high because of their symptoms. All the studies were of low methodological quality, which may question the validity of our findings. Further studies of high methodological quality are necessary.