Ultrasonographic determination of pubic symphyseal widening in trauma: The FAST-PS study

Background: The focused abdominal sonography in trauma (FAST) examination is a routine component of the initial work-up of trauma patients. However, it does not identify patients with retroperitoneal hemorrhage associated with significant pelvic trauma. A wide pubic symphysis (PS) is indicative of an open book pelvic fracture and a high risk of retroperitoneal bleeding. Study Objectives: We hypothesized that an ultrasound image of the PS as part of the FAST examination (FAST-PS) would be an accurate method to determine if pubic symphysis diastasis was present. Methods: This is a comparative study of a diagnostic test on a convenience sample of 23 trauma patients at a Level 1 Trauma Center. The PS was measured sonographically in the Emergency Department (ED) and post-mortem (PM) at the State Medical Examiner. The ultrasound (US) measurements were then compared with PS width on anterior-posterior pelvis radiograph. Results: Twenty-three trauma patients were evaluated with both plain radiographs and US (11 PM, 12 ED). Four patients had radiographic PS widening (3 PM, 1 ED) and 19 patients had radiographically normal PS width; all were correctly identified with US. US measurements were compared with plain X-ray study by Bland-Altman plot. With one exception, US measurements were within 2 standard deviations of the radiographic measurements and, therefore, have excellent agreement. The only exception was a patient with pubic symphysis wider than the US probe. Conclusion: Bedside ultrasound examination may be able to identify pubic symphysis widening in trauma patients. This potentially could lead to faster application of a pelvic binder and tamponade of bleeding.