C. Kaoutzanis1, E. Davies1, S. W. Leichtle3, K. B. Welch2, S. Winter1, M. G. Franz1, W. Arneson1 1St. Joseph’s Mercy Hospital,Department Of Surgery,Ann Arbor, MI, USA 2University Of Michigan,Center For Statistical Consultation And Research,Ann Arbor, MI, USA 3University Of Southern California,Department of Surgery,Los Angeles, CA, USA
Introduction: Acute cholecystitis is one of the most common surgical problems, yet accurate diagnosis of these patients can be difficult given the variable presentation and nonspecific findings that may be present. A substantial debate remains over the utility of physical examination, abdominal ultrasound (AUS), or advanced imaging such as hepato-imino diacetic acid (HIDA) scan to support the diagnosis, alone or in combination. The aim of this study was to establish the diagnostic value of AUS and HIDA scan, which are the two of the most commonly used imaging modalities used for patients with suspected acute cholecystitis.
Methods: The diagnostic imaging workup of patients who presented to the Emergency Department with acute abdominal pain and suspected diagnosis of acute cholecystitis was reviewed to calculate the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of AUS and HIDA scan. The diagnostic value of each AUS finding (gallstones, sludge, sonographic Murphy's sign, gallbladder distension, pericholecystic fluid, gallbladder wall thickening) was also assessed by comparing the percent of patients with and without each finding who were later confirmed histologically to have acute cholecystitis, using a Pearson chi-square or Fisher's exact test.
Results: A total of 3969 emergency room visit charts from November 2009 through May 2011 were reviewed, with 1217 patients meeting inclusion criteria. 1176 patients underwent AUS, 301 underwent HIDA scan, and 260 had both studies performed. Sensitivity, specificity, PPV and NPV of AUS and HIDA scan for all cases with each imaging modality and for cases with both imaging modalities, based on ultimate histological diagnosis, are shown in Table 1. When both imaging modalities were used, the sensitivity, specificity, PPV, and NPV were better for HIDA scan than AUS for diagnosing acute cholecystitis. In addition, the odds of having histologically proven acute cholecystitis were higher when each AUS finding was present versus absent. As the number of AUS findings increased, the odds of having histologically proven acute cholecystitis also increased – 1 AUS finding Odds Ratio (OR) 41.4 (CI 10.8-371.4), 2 AUS findings OR 113.8 (CI 29.7-1020.6), and 3 or more AUS findings OR 261.8 (CI 68.3-2349.4).
Conclusion: In adults with acute abdominal pain presenting to the Emergency Department, the effectiveness of AUS in diagnosing acute cholecystitis increases with the number of AUS findings. However, HIDA scan has superior diagnostic value for identifying patients with acute cholecystitis. An improved understanding of the real-world diagnostic ability of imaging modalities may help develop algorithms for optimum surgical resource utilization.
