Ultrasound for the evaluation of soft tissue foreign bodies before and after the addition of fluid to the surrounding interstitial space in a cadaveric model

• Published in: The American journal of emergency medicine 2016-09, Vol.34 (9), p.1779-1782
• Main Authors: Saul, Turandot, MD, Siadecki, Sebastian D., MD, Rose, Gabriel, DO, Berkowitz, Rachel, MD, Drake, Aaran B., MD, Delone, Noah, MD, Avitabile, Nicholas, DO
• Format: Article
• Language: English
• Subjects: Accuracy; Cadaver; Confidence intervals; Emergency; Emergency medical care; Foreign Bodies - diagnostic imaging; Humans; Injection; Medical imaging; Metals; Point-of-Care Systems; Prospective Studies; Sensitivity and Specificity; Sodium Chloride; Software; Subcutaneous Tissue - diagnostic imaging; Ultrasonic imaging; Ultrasonography; Wood
• ISSN: 0735-6757; 1532-8171
• DOI: 10.1016/j.ajem.2016.06.004

Abstract Background Point of care ultrasound may be used to facilitate foreign body (FB) localization and removal. We hypothesized that injection of normal saline adjacent to an FB may make it easier to detect. Methods The study was performed on one embalmed human cadaver. Potential FB sites were created of wood (24), metal (24) and null (24). Two sonographers evaluated each of the 72 sites both before and after a 25-gauge needle was inserted into each incision and 3 cc of normal saline was injected. Accuracy, sensitivity and specificity were calculated both pre- and post-injection of normal saline. Binomial tests were used to determine the statistical significance of FB detection pre- and post-injection. A two-tailed student's t test was used to determine if there was a statistically significant difference between the two methods. Results Pre-injection, 116/144 (81%, p = < 0.001) of the interpretations were correct in their assessment, with a sensitivity of 81% (95% CI 72% - 88%) and a specificity of 79% (95% CI 65% - 90%). Post-injection, 119/144 (83%, p = < 0.001) of these interpretations were correct in their assessment of whether or not an FB was present, with a sensitivity of 85% (95% CI 77% - 92%,) and a specificity of 77% (95% CI 63% - 88%). This difference was not significant (p = 0.08, CI − 0.04 to 0.01). Discussion Ultrasound was reasonably accurate, sensitive and specific in identifying 1 cm metal and wood FBs. While accuracy and sensitivity did improve after normal saline injection, this difference was not significant.