Lessons learned from quality assurance: errors in the diagnosis of acute cholecystitis on ultrasound and CT

The purpose of this article is to study errors in the diagnosis of acute cholecystitis reported in the online departmental quality assurance (QA) database.

The departmental QA database was searched from October 2005 to April 2010 for cases of acute cholecystitis. Errors were classified into overcalls and undercalls.

We identified 14 cases of misdiagnosis involving acute cholecystitis. Three cases were classified as overcalls (21%) and eleven as undercalls (79%). Eight cases of misdiagnosis involved ultrasound studies (57%) and six cases involved CT studies (43%). Cases of overcall on ultrasound showed gallbladder wall edema, but none portrayed distention of the gallbladder. The final diagnosis in these cases included hepatitis, sepsis, and a case of chronic cholecystitis. All misinterpretations of CT cases were classified as undercalls. Contributing factors to misdiagnosis were lack of recognition of wall edema (n = 6), gallbladder distention (n = 4), absence of gallbladder wall edema (n = 1), lack of conclusion in the report (n = 2), and hospitalization in the ICU (n = 2). A possible case clustering was observed just after July almost every year.

An important pitfall in the diagnosis of acute cholecystitis is lack of recognition of gallbladder wall edema on CT. A relaxed (nondistended) gallbladder provides important evidence against the diagnosis of acute cholecystitis. Intensive care patients with sepsis often have no specific signs for diagnosis of acute cholecystitis, making diagnosis especially challenging.