[Ultrasonic study of the dimensions of the common bile duct in various postures].

To date, the importance of patient position has not been considered in defining the normal range of the internal diameter of the main bile duct. The authors examined 160 patients to verify if significant changes in the internal diameter of the main bile duct take place when changing patient position. In 20/160 cases (12.5%) internal diameter was observed to decrease by greater than 1 mm, in 6/160 cases (3.75%) by greater than 2 mm. These changes were found more often in cholecystectomized patients and were mostly associated with an increase in the max absolute caliber of the main bile duct. Therefore, postural changes (dorsal decubitus, left lateral decubitus, upright position) of the patient are important factors when calculating max internal diameter of the main bile duct. Moreover, postural changes may play an analogous role to functional tests.