Ultrasound evaluation of the common duct in symptomatic and asymptomatic patients.

We studied common duct (CD) diameter using real time ultrasound in 551 patients. The patients were divided into two groups: those referred for evaluation of the biliary tree [biliary-referred group (BRG)], and those referred for a problem unrelated to potential biliary tree pathology [non-biliary-referred group (NBRG)]. Potentially obstructed CDs were excluded from analysis. The CD diameter in the NBRG patients was found to increase after cholecystectomy (p less than 0.0003), but not in patients in this group with intact gallbladders and cholelithiasis. Dilation was observed in the BRG patients with either cholelithiasis (p less than 6 x 10(-7)) or cholecystectomy (p less than 4 x 10(-10)) compared to patients with intact gallbladders without cholelithiasis. To our knowledge, the former phenomenon has not been described in the literature. Our NBRG data suggest that the normal CD diameter should be set at 5 mm and 8 mm, respectively, for patients with intact gallbladders and patients post-cholecystectomy. No correlation was found between duct size and sex, age, or weight.