Systematic Sonography Looking for Occult Wounds: accuracy of an abdominal ultrasound adjunct in penetrating trauma

Background: Systematic Sonography Looking for Occult Wounds (SSLOW) in trauma is a novel technique for the evaluation of intra-abdominal wounds in penetrating trauma. No data exist regarding the effectiveness. The objective of this study was to evaluate the accuracy of the SSLOW exam. Methods: This is a prospective collected case series conducted over a period of 10 months and took place at the Accident and Emergency Department (A&E) of the Georgetown Public Hospital Corporation (GPHC). The study enrolled patients presenting to the A&E who were 16 years old or greater with penetrating abdominal trauma. All patients with penetrating trauma received an E-FAST examination. If the E-FAST examination was negative, a SSLOW examination was completed. The sonographer evaluated for free fluid collection between the loops of bowel. The results of the SSLOW were compared to usual care (surgery consult, serial abdominal and E-FAST exams, laparotomy, and 7-day follow-up) and then categorized into four groups: true positive, false positive, true negative, and false negative. These results lead to four categorical values. From these results, sensitivity, specificity, positive predictive value, negative predictive value, and likelihood ratios were calculated. Results: There were 5 (12%) true positives, 1 (2%) false positive, 37 (86%) true negatives, and zero (0%) false negative. The SSLOW was 100% sensitive (95% CI 5-100%) and 97% specificity (95% CI 74-96%). There was an 80% positive predictive value (95% CI 1.0-64% 95% CI) and 100% negative predictive value (95% CI 88-100%). The positive likelihood ratio was 8.4 (95% CI 3.69-19.1) and negative likelihood ratio was 0. Conclusion: The SSLOW examination may be a useful tool in the evaluation of penetrating abdominal injuries.