Computed Tomography Is More Sensitive than Ultrasound for the Diagnosis of Acute Cholecystitis

Background: Ultrasound (US) is the first-line diagnostic study for evaluating gallstone disease and is considered the test of choice for diagnosing acute cholecystitis (AC). However, computed tomography (CT) is used widely for the evaluation of abdominal pain and is often obtained as a first abdominal imaging test, particularly in cases in which typical clinical signs of AC are absent or other possible diagnoses are being considered. We hypothesized that CT is more sensitive than US for diagnosing AC. Methods: A prospective registry of all urgent cholecystectomies performed by our acute care surgery service between June 2008 and January 2014 was searched for cases of AC. The final diagnosis was based on operative findings and pathology. Patients were classified into two groups according to pre-operative radiographic work-up: US only or CT and US. The US group was compared with the CT and US group with respect to clinical and demographic characteristics. For patients undergoing both tests the sensitivity of the two tests was compared. Results: One hundred one patients with AC underwent both US and CT. Computed tomography was more sensitive than US for the diagnosis of AC (92% versus 79%, p=0.015). Ultrasound was more sensitive than CT for identification of cholelithiasis (87% versus 60%, p<0.01). Patients undergoing both tests prior to surgery were more likely to be older, male, have medical comorbidities, and lack typical clinical signs of AC. Conclusions: Computed tomography is more sensitive than US for the diagnosis of AC and is most often used in patients without typical clinical signs of AC.