Mild asymptomatic intrahepatic biliary dilation after cholecystectomy, a common incidental variant

Objective The purpose of this study is to evaluate the prevalence of intra- and extrahepatic ductal dilatation in asymptomatic individuals after cholecystectomy. Methods and materials This IRB-approved retrospective cohort study evaluated the prevalence of intra- and extrahepatic biliary dilation in 77 consecutive post cholecystectomy patients who had CT obtained in the portal venous phase. These were then compared to age and sex matched control patients. Two radiologists in consensus blinded to surgical history evaluated the intrahepatic ducts qualitatively for dilatation. A single radiologist using the best of three orthogonal planes measured the extrahepatic ducts. Extrahepatic ducts were considered dilated if >7 mm plus 1 mm/decade after 60 years. T tests and chi-squared tests were performed. Results Cholecystectomy patient duct patterns: normal ducts 26% (20/77); intra- and extrahepatic dilation 31.2% (24/77); intrahepatic dilation only 18.2% (14/77); extrahepatic dilation only 24.7% (19/77). Control patient duct patterns: normal ducts 88.3% (68/77); intra- and extrahepatic dilation 2.6% (2/77); intrahepatic dilation only 2.6% (2/77); extrahepatic dilation only 6.5% (5/77). All intrahepatic ductal dilatation was mild. Total intrahepatic dilation: 49.4% (cholecystectomy); 5.2% (control patients). The relative risk of intrahepatic ductal dilation in cholecystectomy patients was 9.5:1. Increased prevalence of intra- and extrahepatic dilation in cholecystectomy patients was statistically significant ( p < 0.0001). Average extrahepatic duct was 7.8 mm (cholecystectomy) and 5.3 mm (control patients) ( p