UTILITY OF ROUTINE LABORATORY TESTING FOR DETECTING INTRAABDOMINAL INJURY IN THE PEDIATRIC TRAUMA PATIENT

Objective. To assess the prevalence of laboratory abnormalities (compl ete blood cell count, electrolytes, blood urea nitrogen, creatinine, g lucose, aspartate aminotransferase, alanine aminotransferase, amylase, lipase, urinalysis [U/A]) and the sensitivity and specificity of the physical examination (PE) and screening laboratory tests for identifyi ng intra-abdominal injury (IAI) in moderately injured pediatric patien ts. Design, participants, and setting. Phase I: Retrospective chart re view of 285 consecutive level II (moderately injured) trauma patients seen at a children's hospital emergency department/pediatric trauma ce nter. All patients were received directly from the scene and had the f ollowing data recorded: mechanism of injury, Glasgow coma score, traum a score, pediatric trauma score, systematically recorded PE findings, laboratory results, and injuries detected during hospitalization. Phas e II: To confirm the sensitivity of the PE and U/A found in phase I, t he model was applied to 91 additional trauma patients identified by In ternational Classification of Diseases, 9th revision (ICD-9) codes as having IAI. Intervention. None. Results. Phase I: A total of 3939 test s were ordered for the 285 patients entered in phase I. Aspartate amin otransferase and alanine aminotransferase values were obtained in 59% of patients; glucose level was obtained in 78% of patients; complete b lood cell count, U/A, and levels of electrolytes, blood urea nitrogen, creatinine, amylase, and lipase were obtained in more than 85% of pat ients. The overall prevalence of laboratory abnormalities was 5.7%. Fo urteen patients (4.8%) were identified who had a total of 23 significa nt IAIs (9 pancreatic, 6 splenic, 5 renal, 3 hepatic). The PE combined with U/A showing more than five red blood cells per high-power field had a sensitivity of 100%, specificity of 64%, positive predictive val ue of 13%, and negative predictive value of 100% for the detection of IAI. The presence of laboratory abnormalities suggesting injury did no t increase the sensitivity of the model and significantly decreased bo th specificity and positive predictive value. Phase II: The PE combine d with U/A identified an abnormality in 89 (97.8%) of 91 cases (95% co nfidence interval = 94.8% to 100%). Conclusions. In the moderately inj ured pediatric trauma patient, (1) there is a low prevalence of labora tory abnormalities; (2) the PE combined with U/A is a highly sensitive screen for IAI; and (3) in patients with a normal PE of the abdomen a nd a normal U/A, laboratory testing seldom identifies unsuspected IAI.