One of the major differences between DNA and RNA is the sugar, with 2-deoxyribose being replaced by the alternative pentose sugar ribose in RNA. The four bases found in DNA are adenine (abbreviated A), cytosine (C), guanine (G) and thymine (T).ne of the major differences between DNA and RNA is the sugar, with 2-deoxyribose being replaced by the alternative pentose sugar ribose in RNA. The four bases found in DNA are adenine (abbreviated A), cytosine (C), guanine (G) and thymine (T).
Common bile duct stone, also known as choledocholithiasis, is the presence of gallstones in the common bile duct (thus choledocho- + lithiasis). This condition causes jaundice and liver cell damage, and requires treatment by cholecystectomy and/or ERCP. 1  1 Signs and symptoms.  2 Causes.
In the published literature the upper limit of the CBD has been reported as 4â10 mm on ultrasound [3] , [4] , [5] , [6] and [7] . The mean diameter of the common bile duct measured by US was reported as 4.1 mm in the study by Parulekar [4] .owever, others found dilatation of the CBD in patients after cholecystectomy [7] and [10] . In this study we aimed to find the size of the normal common bile duct on MDCT. We searched age related changes in the diameter of the common bile duct.