Survey radiographs a.
Abdominal fat is responsible for intra-abdominal serosal detail.
Without fat, intra-abdominal viscera are not discernible. On the other hand, increased abdominal serosal detail is due to pneumoperitoneum. Left side down horizontal beam is indicated to identify a small volume of free abdominal gas. Gas in the retroperitoneal space may be secondary to pneumomediastinum. Ultrasonography Ultrasonography is the best method to confirm or identify small volume of abdominal fluid.