Sonographic features of Lemmel’s syndrome: Differential diagnosis from stones in the lower portion of the common bile duct

Background and study aims Periampullary diverticula (PAD), a location-specific type of duodenal diverticula, can cause serious complications. PAD is difficult to differentially diagnose, mainly due to its nonspecific symptoms. This study aimed to identify sonographic features of PAD and to evaluate their value in the differential diagnosis of PAD from stones in the lower common bile duct (CBD). Patients and Methods A total of 30 patients with PAD and 60 patients with lower CBD stones were retrospectively enrolled, and sonographic features were analyzed. Measurements of sonographic features included echo shaped, posterior echo changes, location and relation to surrounding organs, and status of intrahepatic and extrahepatic bile duct dilation, and their diagnostic performance was assessed. Results Characteristic sonographic features of PAD were identified, including strong echoes (28/30, 93.3 %), strip shape (28/30, 93.3 %), multiple reflections in the posterior echo (27/30, 90.0 %), and location outside the CBD or near the biliary wall in connection with the duodenum (27/30, 90.0 %). Inter-observer agreement was good (Kappa values = 0.69–0.82). Comparative analysis of sonographic features revealed significant differences in echo shape, posterior echo changes (multiple reflections and acoustic shadowing), location and relation to surrounding organs, and intrahepatic and extrahepatic bile duct dilatation status between the dilatation status of the two groups. In particular, these characteristics achieved a sensitivity of 100 % and a specificity of 98 % for the differential diagnosis of PAD and lower CBD stones. Conclusions This study identified characteristic sonographic features of PAD, which could be used as potential diagnostic indicators to distinguish PAD from lower CBD stones.