Open book fractures and ultrasound

For me, this is one of those ‘why didn’t I think of that?!’ studies… extending the FAST scan to measure pubic symphyseal widening to detect open-book pelvic fractures. A pubic symphysis width of 25 mm was considered positive; the authors state that this width is considered diagnostic for anterior-posterior compression fracture of the pelvis in the non-pregnant patient.
Since only four of the 23 patients studied had radiological widening, the authors’ conclusions make sense: Further study with a larger cohort is needed to confirm this technique’s validity for diagnosing PS widening in APC pelvic fractures.
A reasonable question might be: ‘so what?’, especially if pelvic binders are routinely applied to polytrauma patients and radiographs are rapidly obtained. However as a retrieval medicine doctor working in remote and austere environments I wonder whether this could be useful to us. Perhaps if combined with this intervention?

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.

Ultrasonographic determination of pubic symphyseal widening in trauma: the FAST-PS study
J Emerg Med. 2011 May;40(5):528-33

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