What do hyperechoic foci within the intrahepatic ducts most likely represent?

Hyperechoic foci within the intrahepatic ducts most commonly represent pneumobilia, which refers to the presence of gas within the biliary tree. This condition typically arises due to a fistulous communication between the gastrointestinal tract and the biliary system, often following surgical intervention or infection that creates a pathway for air to enter. In sonography, these foci appear as bright echoes within the ducts and may be confirmed with the presence of air artifacts.

Pneumobilia can be differentiated from other conditions based on the appearance of the echogenic foci and the patient’s history or accompanying signs and symptoms. For instance, neither clonorchiasis, which is a parasitic infection leading to biliary obstruction and causes changes in the size or appearance of the ducts, nor choledocholithiasis, which involves gallstones obstructing the bile ducts and might cause dilatation or shadowing, would typically present solely as hyperechoic foci. Cholangiocarcinoma is associated with masses or lesions in the biliary tract and would not typically present merely as isolated foci. Each of these other conditions has a distinct sonographic appearance and clinical significance that differs from the characteristics of pneumobilia.