This is a single-center randomized controlled trial. Eligible subjects meeting inclusion/exclusion criteria will be randomized 1:1 to EUS+ERCP group or ERCP group. Clinical data and patient-reported outcomes are regularly collected at baseline and during follow-up periods. A comparative analysis was conducted to assess the impact of same-session EUS on ERCP strategy modification between two groups, utilizing a structured questionnaire.Secondarily, the safety and efficacy of same-session EUS will be comprehensively evaluated by comparing complication rates, technical success rate and hospitalization costs, length of stay, and radiation exposure between groups.

Inclusion Criteria:

1. Patients aged ≥18 years;
2. Patients with pancreaticobiliary diseases definitively indicated for ERCP (as confirmed by HBP Specialists );
3. No prior history of ERCP;
4. No pancreaticobiliary EUS examinations within the preceding 3 months.

Exclusion Criteria:

1. Patients with clinically confirmed malignant lesions deemed surgically unresectable by multidisciplinary evaluation and requiring pathological diagnosis exclusively for chemotherapy/radiotherapy guidance;
2. Patients with confirmed diagnosis requiring only palliative biliary/pancreatic stent placement for obstructive jaundice ;
3. Patients with anatomical alterations or surgical history affecting EUS feasibility;
4. Severe systemic illness including severe hepatic, renal, cardiopulmonary and cerebrovascular diseases with high risk for endoscopic procedures;
5. Contraindication to iodinated contrast media (allergy or renal impairment preventing ERCP);
6. Pregnancy or lactation;
7. Patients with severe coagulopathy;
8. Declined informed consent;
9. Severe psychiatric disorder/non-cooperation precluding safe procedure.