Best investigation to detect pneumoperitoneum is?
Plain X ray chest, erect REF: Sutton 7th edition page 663-664 Investigation of choice for pneumoperitoneum: Chest X ray erect view Investigation of choice for pneumoperitoneum in patients unable to stand erect: Left lateral decubitus Most sensitive investigation for pneumoperitoneum: CT scan The erect chest film is the best radiograph for showing the presence of small pneumoperitoneum paicularly on right side between liver and diaphragm. It is superior to erect abdomen film for this purpose because in the later the divergent X ray beams penetrate the gas at the top of diaphragm obliquely and this area is also relatively dark due to overexposure. In the erect chest film, however, the top of diaphragm and gas beneath it are penetrated almost tangentially by the X ray beams and the exposure of the diaphragm is optimum to show small amounts of gas. A left lateral decubitus abdominal radiograph is one taken with the patient lying on the left side but with the X-ray beam horizontal. In patients who are unfit to sit or stand for an erect film, it is the projection of choice to show a small pneumoperitoneum. CT scan is, however, the most sensitive method for the detection of peritoneal free gas, with even tiny bubbles of gas being visible.
Plain X ray abdomen, erect
Left lateral decubitus
Plain X ray chest, erect
CT Scan