The Role of Ultrasonography in Detection and Localization of Radiolucent Foreign Body in Soft Tissues of Extremities

Abstract

INTRODUCTION:Retained non-radiopaque foreign body inside soft tissue can be a cause of prolonged morbidity. Detection and localization is difficult task with conventional radiography. Ultrasonography, CT and MRI are other modes of evaluation but both of CT and MRI are expensive and not easily available.METHODS:Twenty three patients were evaluated with ultrasonography (8 MHz linear probe) and X-ray for clinically suspicious non-radiopaque foreignbody in soft tissue of extremities. Clinical presentation, duration of symptoms, anatomical location and foreign bodies retrieved after surgical explorations were recorded.RESULTS:X-ray could not detect any foreign body in all 23 patients. Ultrasound findings were suggestive of foreign body in 19 patients (male: female=2:1, mean age 31.68+/-11.8 years, range 12 - 54 years) which was confirmed after surgical exploration except in one where only foreign bodygranuloma was found. 4 (21%) were not aware of prick injury. Fifteen patients had attempted removal of foreign body themselves or at medical shop or local health post. Interval between injury / symptoms appearance to hospital ranged from 4-56 days. Foot and ankle was involved in 10 (52.6%), calf in 3 (15%), dorsum of hand in 2 (10.5%), palm in 2 (10.5%), shoulder in 1 (5.2%) and knee in 1 (5.2%) case. Foreign bodies retrieved were wood in 12 (63%), thorn in 4 (21%) and bamboo twig in 2 (10.5%) patients.CONCLUSION:Plain X-ray isn't sensitive for detection of non-radiopaque foreign body in soft tissue. Ultrasonography is sensitive and specific fordetection and localization of foreign body which should be included in evaluation for clinically suspicious retained non-radiopaque foreign body in softtissue of extremities.KEYWORDS:non-radiopaque foreign body; sensitivity; specificity; ultrasonography