Abstract
Endoscopic ultrasound with a convex echoendoscope requires positioning of the transducer in three different stations such as the stomach, bulb and descending part of the duodenum. Basic maneuvers include advancement, rotation and deflection by which the bile duct and the duct and parenchyma of the pancreas are continuously observed through confirmation of neighboring organs and vessels. Doppler imaging is employed for discrimination of pancreatobiliary ducts from vessels. The transgastric approach provides images of the liver, the body and tail of the pancreas, and part of the pancreas head. Advancement of the echoendoscope along the portal vein demonstrates the head and body of the pancreas by the confluence. Clockwise rotation of the echoendoscope from the confluence demonstrates the tail of the pancreas. Observation from the bulb of the duodenum provides images of the gallbladder, bile duct, confluence, head of the pancreas, and part of the pancreas body. Clockwise and counterclockwise rotations of the echoendoscope from the confluence demonstrate the head and neck of the pancreas, respectively. Advancement of the echoendoscope along the bile duct demonstrates the proximal side of the duct. Observation from the descending part of the duodenum provides images of the head of the pancreas and the ampulla. After stretching the echoendoscope into the descending part of the duodenum, a longitudinal image of the abdominal aorta is achieved. The lower part of the pancreas head is located at the upper right side of the image. Slow withdrawal of the echoendoscope demonstrates the ampulla.
