Friday, March 18, 2011
Paucis Verbis: Strength of diagnostic tests for cholecystitis
Can you safely say that the patient doesn't have cholecystitis? Can you discharge him for outpatient ultrasonography to assess for symptomatic cholelithiasis?
As bedside ultrasonography becomes more of a staple in Emergency Departments, it is easy to just perform the ultrasound yourself if such a patient presents. If you do not have an ED ultrasound available, however, you need to send this patient for a formal ultrasound because he is still very much at risk for cholecystitis despite having unremarkable lab tests and no fever.
JAMA published a meta-analysis of 17 studies on the test characteristics for cholecystitis. I found it odd that they defined a fever as temperature >35 Celsius. The best performing characteristic was a Murphy's sign, although the positive likelihood ratio (LR) slightly crossed 1.0 (0.8-8.6).
Trowbridge, R. (2003). Does This Patient Have Acute Cholecystitis? JAMA: The Journal of the American Medical Association. 2003; 289 (1), 80-86. DOI: 10.1001/jama.289.1.80