Imaging of common bile duct by linear endoscopic ultrasound

Table 1 Common bile duct imaging from various stations during endoscopic ultrasound

Station	Home base structure	Main part of bile duct seen	Part of CBD seen on clockwise rotation1	Part of CBD seen anti clockwise rotation2
OG junction	l tributaries of LPV segment 2 and 3	Segment 2 and 3 duct	Upper 1/3	None
Body of stomach	Portal vein, splenic vein	Mid 1/3	Lower 1/3	Upper 1/3, left hepatic duct
Duodenal bulb	Portal vein	Mid 1/3	Lower 1/3	Upper 1/3
Descending duodenum	SMV	Lower 1/3	Mid 1/3, upper 1/3	Intrapancreatic
Antrum	SMV	Lower 1/3	Mid 1/3, upper 1/3	None

¹Clockwise rotation needs to be combined with additional push in and out, and up and down movements;

²Anti-clockwise rotation needs to be combined with additional push in and out, and up and down movements. Each of these positions brings the transducer closer to one of the four parts of CBD (upper 1/3, mid 1/3, lower 1/3 or intraduodenal) and the rest of CBD can be imaged by appropriate movement (clockwise or anti clockwise rotation, right or left movement or up and down movement). If mid 1/3 of CBD is identified in bulb an anti-clockwise rotation shows upper 1/3 CBD and clockwise rotation shows lower 1/3 of CBD. Similarly in stomach once mid 1/3 of CBD is identified clockwise rotation traces CBD towards lower 1/3 and anti-clockwise rotation traces CBD towards upper1/3. CBD: Common bile duct; SMV: Superior mesenteric vein; LPV: Left portal vein; OG: Oesophagogastric junction.