SENSITIVITY AND SPECIFICITY OF ULTRASOUND IN THE DIAGNOSIS OF FOREIGN-BODIES IN THE HAND

High-resolution ultrasound is capable of detecting foreign bodies of p ractically any composition. The purpose of this study was to determine in a controlled manner the sensitivity and specificity of ultrasound in the diagnosis of foreign bodies in the hand. Each of 15 fresh-froze n cadaver hands was divided into 21 standardized sites for potential f oreign body insertion. Foreign bodies consisted of two sizes of three different materials (wood, glass, and metal). Foreign bodies were rand omly assigned to 50% of the available sires. The empty sites served as controls. All hands were scanned by a single radiologist using high-r esolution ultrasound at a frequency of 10 MHz. The radiologist was una ware of which specimens contained foreign bodies. Of the 166 foreign b odies inserted in total, 156 were detected by ultrasound. Ten sites we re falsely analyzed as negative, for a sensitivity of 94%. There was o ne false positive result and 148 true negatives. The specificity was t herefore 99%. The high specificity of ultrasound allows foreign body p resence to be confirmed given a positive result. A combination of ultr asound and x-ray films should allow for diagnosis and localization of virtually all foreign bodies in the hand.