Radiography for midfacial trauma: is a single OM 15 degrees radiograph as sensitive as OM 15 degrees and OM 30 degrees combined?

Two previous studies have suggested that a single occipitomental (OM) 15 degrees radiograph may be sufficient for screening for midfacial fractures in the Accident and Emergency (A&E) department, but the study had insufficient power to detect whether some fractures might be missed with only one projection. We undertook to determine whether there is a decreased sensitivity for detecting fractures if only a single OM 15 degrees radiograph is used rather than OM 15 degrees + 30 degrees. 44 cases of major and minor midfacial fractures interspersed randomly with 49 cases of facial injury without fracture were shown to nine A&E clinicians. Initially they were shown only the OM 15 degrees radiograph, then the OM 30 degrees radiograph alone, and then the two radiographs together. They were asked each time to indicate the presence or absence of fracture. The sensitivity for the OM 15 degrees projection alone was 89.4%, and when both radiographs were used it was 90.9% (difference not significant). Given the positive yield of facial radiographs is only 6%, any minimal increase in sensitivity from using two projections is likely to be outweighed by the beneficial reduction in X-ray exposure and costs from using only a single projection. The policy of using a single OM 15 degrees radiograph as a screening tool for midfacial fractures in A&E is a safe one.