AP image from an UGI exam (left) shows dilation of the stomach and first and second parts of the duodenum. There is an abrupt transition in bowel contour at the ligament of Treitz which projects low in position and over the middle of the spine. The jejunum then appears to spiral away downstream. AP image from later in the exam (right) better shows the spiraling / corkscrew appearance of the proximal jejunum.
