Radiographic screening for glass foreign bodies--what does a "negative" foreign body series really mean?

This study was designed to provide percentages of radiographic detection of small glass foreign bodies and to compare the detection rates (sensitivity) of two-view posteroanterior and lateral with those of four-view posteroanterior, lateral, and right and left obliques screening radiographs. Three sizes (0.5, 1.0, and 2.0 mm, maximum dimension) of beer bottle glass fragments were inserted into chicken legs and radiographed. Three staff radiologists reviewed the films independently. With two-view radiography, the 2.0-, 1.0-, and 0.5-mm glass fragments exhibited 99%, 83%, and 61% average detection rates, respectively. An analysis of variance and a Tukey's range test demonstrated that the variation in the average detection rate with respect to size was statistically significant (P less than .01). X2 Analysis failed to demonstrate a statistically significant (P greater than .05) increase in average detection rates with four-view radiography. The results of this study indicate that the size of the glass foreign body is often the limiting factor for radiographic detection and that 0.5- to 2.0-mm fragments represent a "limited detection" size range. Furthermore, two-view radiography is appropriate and more cost-effective than four-view radiography for screening purposes.