Endoscopic retrograde cholangiopancreatography versus intraoperative cholangiography for the diagnosis of common bile duct stones

Cochrane: The liver has various functions. Production of bile is one of these functions. The common bile duct (CBD) is the tube through which bile flows from the gallbladder (where bile is temporarily stored) into the small bowel. Stones in the CBD (CBD stones) can obstruct the flow of bile from the liver into the small bowel. Usually such stones are formed in the gallbladder and migrate into the CBD. Obstruction of the flow of bile can lead to jaundice (yellowish discolouration of skin and white of the eyes, and dark urine), infection of the bile duct (cholangitis), and inflammation of the pancreas (pancreatitis), which can be life threatening.
Various diagnostic tests can be performed to diagnose CBD stones. Depending upon the availability of resources, these stones are removed endoscopically (a tube inserted into the stomach and upper part of small bowel through mouth; usually the case), or may be removed as part of the laparoscopic operation (key hole surgery) or open operation performed to remove the gallbladder (cholecystectomy; it is important to remove the gallbladder since the stones continue to form in the gallbladder and can cause recurrent health problems). If the stones are removed endoscopically, presence of stones is confirmed by endoscopic retrograde cholangiopancreatography (ERCP) (injection of dye into the CBD using an endoscope) before endoscopic removal of CBD stones. Alternatively, intraoperative cholangiography (IOC) (injection of dye into the biliary tree during an operation to remove the CBD stones, usually combined with an operation to remove gallstones) can be performed to detect CBD stones prior to operative removal of the stones. We performed a thorough search for studies that reported the accuracy of ERCP or IOC for the diagnosis of CBD stones. The evidence is current to September 2012.
Study characteristics
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.
Key results
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.
Quality of evidence
All the studies were of low methodological quality, which may question the validity of our findings.
Future research
Further studies of high methodological quality are necessary.

Authors' conclusions: 

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.