What is use of CXR in acute abdomen?

● Simple radiology imaging done for any acute abdominal pain: chest X-ray upright position (while standing). ● If there’s pneumonia, pleural effusion, pericardial effusion all may cause acute abdominal pain on the same side. ● It is ordered upright to check if there’s free air under the diaphragm in the peritoneum. So diagnostic test of pneumoperitoneum, if we are searching for an intestinal perforation is chest x-ray upright not KUB upright because Chest X-ray upright shows diaphragm and the air accumulated under it. Upright CXR is for perforation dx