Pitfalls of diagnosing

What are the potential pitfalls of diagnosing gallstones?

Usually, it is not difficult to diagnose gallstones. Problems arise, however, because of the high prevalence of silent gallstones and the occasional gallstone that is difficult to diagnose.

If a patient has symptoms that are typical for gallstones, for example, biliary colic, cholecystitis, or pancreatitis, and has gallstones on ultrasonography, little else usually can or needs to be done to demonstrate that the gallstones are causing the episode unless the patient has complicating medical issues.

If episodes are not typical for gallstones, however, any gallstones found may be silent. These silent gallstones may be innocent bystanders, and most importantly, removing the gallbladder surgically will not treat the acute problem or prevent further episodes. In addition, the real cause of the problem will not be pursued. In such a situation, there is a need to have further evidence, other than their mere presence, that the gallstones are causing the episode. Such evidence can be obtained during an episode or shortly thereafter.

If ultrasonography can be done during an episode of pain or inflammation caused by gallstones, it may be possible to demonstrate an enlarged gallbladder or bile duct caused by obstruction of the ducts by the gallstone. This is likely to require ultrasonography again after the episode has resolved in order to demonstrate that the gallbladder indeed was larger during the episode than before or after the episode. It is easier to obtain the necessary ultrasonography if the episode lasts several hours, but it is much more difficult to obtain ultrasonography rapidly enough if the episode lasts only 15 minutes.

Another approach is to test the blood for abnormal liver and pancreatic enzymes. The advantage here is that the enzymes, though not always elevated, can be elevated during and for several hours after an episode of gallstone-related pain or inflammation, so they might be abnormal even after the episode has subsided. It is important to remember, however, that the enzymes are not specific for gallstones, and it is necessary to exclude other liver and pancreatic causes for abnormal enzymes.

Sometimes, episodes of pain or inflammation may be more or less typical of gallstones, but transabdominal ultrasonography may not demonstrate either gallstones or another cause of the episodes. In this case, it is necessary to decide whether suspicion is high or low for gallstones as a cause of the episodes. If suspicion is low because of less typical symptoms, it may be reasonable only to repeat the ultrasonography, obtain an OCG, and/or test for abnormalities of liver or pancreatic enzymes. If suspicion is high because of more typical symptoms, it is reasonable to go even further with endoscopic ultrasonography, ERCP, and duodenal drainage. Prior to these "invasive" procedures, some physicians recommend MRCP; however, the exact role of MRCP is not yet clear.

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