Ultrasound for the detection of foreign bodies in human tissue

Study objective: To determine the accuracy of detection of wood and plastic foreign bodies in human tissue by relatively inexperienced clinicians using typical ultrasound equipment. Methods: Uniform wood and plastic foreign bodies were placed through small punctures into recently amputated human legs. Identical control punctures contained no foreign bodies; the sequence of foreign bodies and controls for the puncture sites was randomized. A second blinded investigator scanned each puncture site with a 7.5-MHz ultrasound probe to determine the presence or absence of foreign material. Results: Eighty punctures were scanned. Ultrasound detected 44 of 53 foreign bodies (83% sensitivity). Wood foreign bodies were detected 25 of 27 times (93%) and plastic foreign bodies 19 of 26 times (73%; P=.13). Overall, there were 11 false-positive readings (59% specificity). Conclusion: Ultrasound is imperfect but may be useful in screening for superficial foreign bodies in human tissue. Clinical utility in the ED setting remains to be tested.