The normal CBD diameter is approximately 3-6 mm, but will generally increase in size with age. A good rule of thumb is to add one millimeter for each decade of life after the age of 40.
It is normal for the CBD to be dilated and remain dilated after surgery.
Measure the CBD just proximal to the hepatic artery in the longitudinal image of the CBD and the main portal vein. Measure from Inner wall to inner wall.
