American Board of Internal Medicine (ABIM) Certification Practice Exam

What imaging finding is indicative of acalculous cholecystitis?

1. Presence of gallstones on ultrasound

2. Gallbladder visualization on a radionuclide biliary scan

3. Ultrasound findings of acute cholecystitis

4. CT scan showing gallbladder inflammation

The correct answer is: Ultrasound findings of acute cholecystitis

Acalculous cholecystitis is characterized by inflammation of the gallbladder in the absence of gallstones. The correct imaging finding indicative of this condition is the ultrasound findings of acute cholecystitis, which typically include gallbladder wall thickening, fluid around the gallbladder, and a lack of gallstones. In acalculous cholecystitis, the gallbladder may be swollen and demonstrate signs of inflammation without the presence of calculi (gallstones). This condition is often seen in critically ill patients or those who have had prolonged fasting, making the ultrasound findings integral for diagnosis. While options that mention the presence of gallstones or visualization of the gallbladder on a radionuclide biliary scan can indicate other forms of gallbladder disease, they do not specifically point to acalculous cholecystitis. The CT scan showing gallbladder inflammation may also not specify the absence of stones, making it less definitive for diagnosing acalculous cholecystitis compared to the ultrasound findings that specifically highlight the characteristics of acute inflammation without gallstones.