Computed tomography and blunt abdominal injury: patient selection based on examination, haematocrit and haematuria

The criteria for ordering abdominal CT scans in the secondary survey of stable bluntly injured patients was examined. A patient population at high risk for having intra-abdominal injury (IAI) was identified by physical examination, a fall in haematocrit, and haematuria. A total of 444 patients receiving abdominal CT scans at a large urban trauma centre were reviewed. IAI was diagnosed in 49 (11 per cent), by radiographic and/or intra-operative findings. Abdominal tenderness was present in all 17 patients who underwent surgery. The sensitivity and specificity of abdominal CT scanning was 90 per cent and 99 per cent, respectively. The abdominal exam had a sensitivity of 63 per cent and a specificity of 65 per cent. A fall in haematocrit ≥5 was not statistically significant. The combined abdominal exam and haematuria yielded a specificity of 93 per cent with a negative predictive value (NPV) of 93 per cent. Early CT scanning of stable patients who had sustained blunt injuries is an effective screen for IAI. The benefit of a CT scan for patients without abdominal tenderness or with an isolated fall in haematocrit is questionable. Serial abdominal examinations should remain the most timely and cost-effective method for identifying IAI in stable patients. The specificity and NPV of abdominal tenderness combined with haematuria approaches that of CT.