Skull X-rays after trauma: are both laterals necessary?

Eighty-eight sets of skull X-rays, each showing an unequivocal skull fracture, were examined by a radiologist under controlled conditions to see if fractures would be missed if only one lateral view was included in the X-ray series. The fracture sets were mixed at random with four times as many normal sets of skull X-rays and each fracture set was examined on two occasions, once with one lateral and once with both laterals. Two of the fractures were not visible when only one lateral was available.