Mini Board Review: March 2013 Edition

#3

ANSWER B.

This patient has suspected acute cholecystitis and requires an imaging study for confirmation. Hepatobiliary iminodiacetic acid (HIDA) scanning is considered to be the most sensitive and specific test for diagnosing acute cholecystitis. IDA is administered intravenously, taken up by hepatocytes, and excreted into the bile canaliculi. Failure to obtain an outline of the gallbladder within 1 hour proves cystic duct obstruction and, in the appropriate clinical setting confirms the diagnosis of acute cholecystitis. Visualization of the gallbladder and common duct within 1 hour has a high negative predictive value. A HIDA scan is usually obtained when the ultrasound study is equivocal.

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Computed tomography scan with intravenous contrast (A) can identify cholecystitis with a reported sensitivity of 92% and specificity of 99%.  It is most useful in cases of emphysematous and hemorrhagic cholecystitis. MRI with gadolinium (C) provided similar diagnostic yield to CT scan. Ultrasound (D) is most useful in the ED setting as it is a quick, non-invasive test.  Its sensitivity and specificity, however, are lower than a HIDA scan for pathology confirmed cholecystitis. Ultrasound findings and a clinical exam consistent with acute cholecystitis are highly predictive and many such patients will undergo cholecystectomy without any further diagnostic testing.

Ref
Guss DA, Oyama LC: Disorders of the Liver and Biliary Tract, in Marx JA, Hockberger RS, Walls RM, et al (eds): Rosen’s Emergency Medicine: Concepts and Clinical Practice, ed 7. St. Louis, Mosby, Inc., 2010, (Ch) 88:p 1153-1171

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