Emergency Physician Use of Ultrasonography in Blunt Abdominal Trauma

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Abstract
To evaluate the diagnostic utility of abdominal diagnostic ultrasonography (DUS) performed by emergency physicians for intraperitoneal fluid caused by blunt abdominal trauma (BAT). The design was a prospective, blind, observational study. During a 15-month period, a convenience sample of patients presenting to the ED with BAT necessitating CT scan of the abdomen, diagnostic peritoneal lavage (DPL), or laparotomy was studied. Scans were performed by an emergency medicine (EM) attending, or a resident supervised by an attending, using a real-time sector ultrasound scanner with a 3.5-MHz probe. Training in DUS included a 1-hour didactic session and 1 hour of practice on human volunteers. Free intraperitoneal fluid was defined as an anechoic stripe in the hepatorenal, bladder-rectal, or splenorenal space, and constituted a positive DUS study. Free intraperitoneal fluid detected on abdominal CT scan, DPL, and/or laparotomy was the criterion standard. Of 110 patients scanned, 13 were excluded secondary to technical difficulty or lack of diagnostic follow-up modalities. Of the remaining 97 patients, there were 24 females and 73 males, ranging from ages 2 to 78 years. DUS detected intraperitoneal fluid in 21 subjects, including 3 false positives. There were 6 false-negative DUS examinations. DUS had a sensitivity of 75% (95% CI 53-90%), a specificity 96% of (95% CI 89-99%), and an accuracy of 91% (95% CI 83-96%). No false-positive or false-negative DUS study occurred after the first 67 cases. The mean interval for a DUS scan was 4.9 +/- 2.9 minutes, ranging from 0.5 to 16 minutes, and the mean intervals were not different between the positive and the negative studies. The accuracies of DUS were similar in the pediatric patients, 97% (95% CI 83-100%), and in the adults, 88% (95% CI 78-95%). The hepatorenal view provided the highest sensitivity as well as the least number of uninterpretable scans of the 3 DUS views. Emergency physicians with minimal training can use DUS with fair sensitivity and good specificity and accuracy to detect free intraperitoneal fluid in both pediatric and adult BAT victims. The hepatorenal view provides the highest sensitivity for intraperitoneal fluid, although the 3-view series (with hepatorenal, bladder-rectal, and splenorenal spaces) can typically be performed within 5 minutes and may increase the specificity and accuracy.