Study objective: To determine whether abdominal ultrasound can be used routinely as the primary screening test to identify the need for laparotomy in trauma patients. Methods: Ultrasound was used at a Level II trauma center as a primary screening test for evaluation of intraabdominal injury. We reviewed the charts of all patients from trauma codes presenting between January 1, 1991, and December 31, 1993, to determine the results of abdominal ultrasound evaluation and to learn whether laparotomy was required. Results: A total of 2,013 trauma patients presented during the study interval. Ultrasound was performed in 1,631 patients as the primary screening test for abdominal injury (mean time after arrival, 22.9 minutes), abdominal computed tomography (CT) was performed as the primary screen on 8 (mean time, 68.6 minutes), and 93 patients underwent both ultrasound and CT of the abdomen. Of 86 patients requiring laparotomy who were screened by ultra sound, 80 had positive diagnostic findings, for a sensitivity of 93.0%. Of the 1,545 ultrasound-screened patients who did not require laparotomy, 1,390 had negative findings, for a specificity of 90.0%. None of the patients with negative ultrasound results died or sustained identifiable mortality as a consequence of their negative scans. Conclusion: Ultrasound is a sensitive and specific test with which to evaluate trauma patients for abdominal injury requiring surgery. Routine abdominal ultrasound can be performed at the bedside in the emergency department as a timely, noninvasive diagnostic test. This use of a screening abdominal ultrasound examination can improve clinical decision-making for the use of emergency laparotomy. Ultrasound may be a better alternative to CT or diagnostic peritoneal lavage for the initial screening evaluation of abdominal trauma.