Matt Berger, MD PGY1
Article: A Prospective Evaluation of Emergency Department Bedside Ultrasonography for the Detection of Acute Cholecystitis. Summers et al. Annals of Emergency Medicine 2010. 56. 114-122
Background: Radiology performed ultrasound is a common first choice for patients presenting to the emergency department with concern for acute cholecystitis, however there are limitations such as availability, transport and need for fasting that can increase emergency department length of stay and make radiology ultrasound less feasible. Therefore, many emergency department physicians are increasingly using bedside ultrasound to evaluate for acute cholecystitis. Previous studies comparing radiology to bedside ultrasound have only tested interobserver reliability but not clinically useful outcome measures. This study looks to compare and determine the test characteristics of bedside and radiology ultrasound for the detection of acute cholecystitis as defined by surgical pathology.
Study Details: This was a single center, prospective, observational study out of the University of California, Irvine emergency department. Patients were 18 years old or older and presenting to the emergency department with suspected acute cholecystitis. Once enrolled, all patients underwent bedside ultrasound performed by a resident, fellow or attending. After this, further management was determined by the attending physician and could include radiology ultrasound, surgical consult and admission or discharge home with outpatient follow up, but none of these were required. Bedside ultrasound results and radiology ultrasound results were then compared to the standard of surgical pathology or clinical follow up reports at 2 weeks.
Primary outcome: acute cholecystitis as determined by surgical pathology (negative if negative surgical pathology or unremarkable clinical follow up)
Secondary objective: compare test characteristics of sonographic Murphy’s sign, gallbladder wall thickening and pericholecystic fluid to the standard of surgical pathology
Bedside and radiology ultrasounds were considered positive if they showed cholelithiasis PLUS any one of sonographic Murphy’s sign, gallbladder wall thickening (>3mm) or pericholecystic fluid.
Results: 164 patients were included in the study for final data analysis. 26 of these patients went to the operating room for cholecystectomy and all of them had a radiology ultrasound in addition to their bedside ultrasound. 23 of the 26 had acute cholecystitis by surgical pathology with 1 pathology report indicating cholelithiasis only and 2 reports unavailable. 140 patients were discharged home and none of these had cholecystectomy within 2 weeks of discharge. When comparing bedside ultrasound against radiology ultrasound, there were no significant differences. Bedside ultrasound had sensitivity 87%, specificity 82%, positive predictive value 44% and negative predictive value 97%. Radiology ultrasound had sensitivity 83%, specificity 86%, positive predictive value 59% and negative predictive value 95%. There were also no significant differences in the test characteristics of sonographic Murphy’s sign, gallbladder wall thickening or pericholecystic fluid between bedside ultrasound and radiology ultrasound. However, no one secondary finding was sensitive enough to exclude cholecystitis in either group. Additionally, 64 patients were discharged home after only receiving bedside ultrasound, without radiology ultrasound, and none of these patients underwent cholecystectomy or admission within the next 2 weeks or had any adverse outcomes.
Limitations/Bottom Line: The overall conclusion in this study is that bedside ultrasound performs similarly to radiology ultrasound for the detection of acute cholecystitis compared to the standard of surgical pathology. Also, none of the patients who were ruled out for having acute cholecystitis by bedside ultrasound alone had adverse outcomes. This study would suggest that emergency department performed bedside ultrasound is just as good as radiology ultrasound and can be done much more quickly and efficiently. However, this study did have several limitations. It was a small, single center study with a relatively small number of participants. Also, every patient who underwent a bedside ultrasound did not necessarily undergo a radiology ultrasound, which was unusual since those were the modalities being compared. Lastly, clinicians performing bedside ultrasound were not blinded to clinical history/data which may have yielded some confirmation bias. Although, I see this as a strength for bedside ultrasound in that it allows for added clinical data with the clinician performing the test and caring for the patient also being the one to interpret the test results. Overall this was a helpful study in showing that bedside ultrasound has an important role in the management of acute cholecystitis patients in the emergency department and is just as good as radiology ultrasound.