The FAST exam (focused assessment with sonography in trauma) looks for two things - intraperitoneal free fluid in the abdomen and fluid around the heart. With regard to the abdomen, there are a lot of places the fluid can go. It would be helpful to know in which areas the fluid most commonly collects so you can make sure not to miss any. These authors break down each of the three abdominal FAST views (right upper quadrant, left upper quadrant, and suprapubic/pelvic) into three "sub-quadrants." Then they take a look at all the FAST exams done at their institution over a year and a half and determine how often the fluid goes to each of those places when there is a positive exam.