The identification of a biliary obstruction remains a major diagnostic challenge in the management of pancreatobiliary disorders. Despite advances in conventional imaging, certain obstructions may go undetected, making etiological diagnosis uncertain.Endoscopic ultrasound (EUS) provides higher resolution and direct visualization of the common bile duct, allowing the detection of abnormalities that may not be visible on CT or MRI.The aim of this study was to assess the diagnostic performance and yield of EUS in detecting biliary obstructions not identified by conventional imaging, and to determine its added value in patient management.

This was a retrospective, descriptive, and analytical study conducted in the endoscopy unit between January 2019 and October 2025.All patients who underwent endoscopic ultrasound (EUS) for suspected biliary obstruction not visualized on conventional imaging (CT or MR cholangiopancreatography) were included.Clinical, biological, radiological, and endoscopic data were collected from medical records and analyzed.

A total of 27 patients were included. The mean age was 63 years (range: 31–90), with a female predominance (70%) and a male-to-female ratio of 0.4.A history of cholecystectomy was found in 9 patients (33%), and a prior ERCP in 1 patient (3.7%). 

Clinically, jaundice was observed in 17 cases (63%), biliary pain in 17 cases (63%), pancreatic-type pain in 11 cases (41%), and atypical pain in 1 case.Fever was reported in 4 patients (15%), and weight loss in 8 cases (30%).

Biochemically, 19 patients (70%) showed abnormal liver function tests, with a mean total bilirubin of 56 µmol/L.

All patients had undergone conventional imaging, including CT in 13 cases (48%) and MR cholangiopancreatography in 14 cases (52%).At imaging, common bile duct (CBD) dilation was noted in all patients, with a mean diameter of 12.4 mm (range: 8–20 mm), and intrahepatic bile duct (IHBD) dilation in 23 cases (85%).

EUS confirmed CBD dilation in just 14 patients (52%), with a mean diameter of 10.5 mm (range: 6–17 mm).EUS identified a biliary obstruction in 19 cases (70.3%). The main etiologies identified were common bile duct stones (29.6%), congenital cystic dilatation of the common bile duct   in 7.4%, and LPAC syndrome in 7.4%. Less frequent causes included distal cholangiocarcinoma in 3.7%, pancreatic head tumor in 3.7%, chronic pancreatitis in 3.7%, fibrosing papillitis in 3.7%, and paraduodenal pancreatitis in 3.7%.

EUS-guided fine-needle aspiration (FNA) was performed in 4 patients (14.8%).Histological analysis revealed adenocarcinoma in two cases, a carcinomatous process in one case, and primary sclerosing cholangitis in one case.ERCP was performed in 18 patients (67%), confirming the diagnosis made by EUS.

The overall diagnostic yield of EUS was 70.3%.CBD dilation was ruled out in 13 patients (48.1%), and no obstruction was identified in 8 cases (29.6%). No major EUS-related complications were observed.

Endoscopic ultrasound is a reference diagnostic tool for evaluating suspected biliary obstructions not visualized on conventional imaging.In this study, EUS identified an obstruction in nearly 70.3% of cases, confirming its high diagnostic yield and added value in the biliary diagnostic pathway.Beyond its diagnostic accuracy, EUS plays a key role in therapeutic decision-making, particularly by guiding ERCP or tissue sampling.These findings emphasize the essential role of EUS in the diagnostic algorithm of unexplained biliary dilations and support its early integration in clinical practice.