Interpreting a radiograph of the abdomen

The plain abdominal radiograph is commonly used in the investigation of the acute abdomen, and the admitting surgeon makes early decisions based on it. The standard films obtained are a supine abdominal and erect chest views. The relative merits of the erect abdominal film are discussed, since the presence of fluid levels does not necessarily indicate obstruction to the small bowel. The abnormalities seen on a supine abdominal X-ray are divided into broad categories as follows; abnormal distribution of gas – especially pneumoperitoneum, retroperitoneal gas, and gas in the bowel wall; dilatation of the bowel – namely stomach, small bowel and large bowel; abnormal bowel wall pattern – including ischaemia, infarction and inflammatory bowel disease; and some inflammatory conditions of the abdomen, including appendicitis.