Objective  To evaluate the feasibility and effectiveness of linear array endoscopic ultrasonography (L-EUS) in the differential diagnosis of stricture lesions in the lower common bile duct (CBD).

Methods Clinical data of 75 patients admitted to DongGuan Tungwah Hospital from August, 2022 to November, 2023 were collected. All patients showed the dilatation of the upper common bile duct on abdominal ultrasound, but the etiology of lower segment strictures was unclear. They underwent upper abdominal CT scan, magnetic resonance cholangiopancreatography (MRCP) and L-EUS. Based on these results, the final diagnosis was confirmed by endoscopic retrograde cholangiopancreatography (ERCP) or surgical operation. Patients with negative findings were subject to 18-month outpatient follow-up, once every 2-3 months. The positive detection rates of upper abdominal CT, MRCP, and L-EUS for the etiology of CBD strictures were compared. Taking ERCP, surgical findings, and follow-up results as the gold standard, the differential diagnostic ability of L-EUS was evaluated.

Results Compared with upper abdominal CT and MRCP (both P ＜ 0.05), L-EUS had the highest positive detection rate (53.3%) for the etiology of CBD stricture, approaching that of the gold standard (56.0%). The accuracy of L-EUS in identifying the etiology of CBD strictures was 94.7%. For CBD stones, the sensitivity, specificity, and accuracy of L-EUS were 93.3%, 100%, and 97.3%, respectively.

Conclusions L-EUS has high value in localizing and qualitatively diagnosing CBD stricture lesions, especially for the diagnosis of CBD stones. For patients with CBD dilatation which cannot be confirmed by routine ultrasound, L-EUS can be used to further clarify the etiology of lower segment stricture and may serve as an effective alternative to upper abdominal CT or MRCP when feasible. For patients with negative L-EUS findings, further ERCP or close follow-up is recommended if necessary.