['The detection of isolated intestinal injuries after blunt trauma can be difficult because of subtle signs and symptoms, often leading to delayed diagnosis. We hypothesized that specific clinical indicators could be identified to assist in the diagnosis of these injuries.', 'Medical records of all patients with such injuries from 1988 to 1996 were reviewed. The patients were stratified into those operated on within 6 hours of presentation (apparent injury) and those operated on after 6 hours (occult injury), and the data were compared.', 'Forty-six patients with isolated intestinal injuries were identified. There were no differences in the rate of peritonitis or free fluid on abdominal computed tomography, blood loss, intraoperative findings, or morbidity and mortality between groups. Leukocytosis (sensitivity, 84.8%; specificity, 55.2%; p = 0.01) and free fluid on computed tomography were frequently present, however, and their significance was underappreciated in the occult injury group.'] Are leukocytosis and free fluid important indicators of isolated intestinal injury after blunt trauma?