Pain from abdominal viscera often (but not always) localizes according to the structure's embryologic origin, with foregut structures (mouth to proximal one-half of duodenum) presenting with upper abdominal pain, midgut structures (distal one-half of duodenum to middle of the transverse colon) presenting with periumbilical pain, and hind gut structures (remainder of colon and rectum, pelvic genitourinary organs) presenting with lower abdominal pain. Radiation of pain may provide insight into the diagnosis. As examples, pain from pancreatitis may radiate to the back, while pain from gallbladder disease may radiate to the right shoulder or subscapular region.