Dilated common bile duct unexplained on transabdominal ultrasonography; the role of endoscopic ultrasonography and predictors of malignancy

Background:  The aim of the this prospective study was to evaluate  the endoscopic ultrasonography (EUS) in detecting the cause of common bile duct (CBD) dilatation in patients in whom ultrasonography(US) could not indicate  the cause of dilation. Methods:  Seventy patients with the search criteria of unexplained dilated CBD (diameter > 7 mm) were examined by EUS. All patients (except 4 patients with pancreatic mass) were further evaluated by ERCP. Results: The following diagnoses were made by EUS and ERCP: choledocholithiasis in 45, pancreato-biliary malignancy (PBM) in 17, papillary stenosis in 5, and no finding in 3 cases. We found that the majority of patients (95.7%) had findings on EUS to explain the etiology of their dilated CBD. The prevalence of pathology is lower (76.9%) in patients with normal liver function tests (LFTs).The yield of EUS is higher (100%) when elevated liver enzymes. Lower hemoglobin levels, larger diameter of CBD and pancreatic duct (PD) and ESR greater than 30 mm/h were independent risk factors for PBM, whereas, patients with previous cholecystectomy, normal LFTs and abdominal pain were less likely to have this diagnosis. Conclusion: the majority of patients referred for EUS for dilated CBD will have an etiology discovered Therefore, EUS should be the first diagnostic strategy for dilated CBD of unexplained origin, even in patients with normal LFTs. In patients with dilated CBD accompanied by anemia, abnormal LFTs and ESR or dilated PD, malignancy should be considered.