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E1294. Pining for Relief: Ultrasound-Guided Foreign Body Removal from Lower Extremity
Authors
  1. Drew McKinney; St. George's University
  2. Saad Farooq; KPC Health
  3. Krishna Das; Victor Valley Global Medical Center
  4. Rahul Nayyar; Victor Valley Global Medical Center
Background
Foreign body (FB) removal from superficial soft tissues is a commonly performed procedure that is ideally done under ultrasound (US) guidance. When not removed a FB can serve as a source of pain or irritation, as an entry point for pathogens, or as a source of obstruction. Ultrasound is not only used to visualize the area, eliminating the need for probing which could be damaging to the examiner and/or patient, but it is also important in ensuring the complete removal of the object. Visualization of the object and its surrounding tissue is especially necessary in chronic cases where scarring or granulation may make evaluation difficult. Ultrasound has a high specificity (70-97%) and a moderate sensitivity (50-90%) for the identification of various organic and non-organic items (1), making it ideal for thorns or splinters, which may be radiolucent on other forms of imaging (2). Although CT may in some cases be more sensitive for localizing objects, its high relative cost makes it a less viable option. 

Educational Goals / Teaching Points
This paper will demonstrate a case of foreign body removal using ultrasound guidance. We will also discuss the typical sonographic appearance of foreign bodies.  The utility of US in visualizing the foreign body, pre-procedural planning, intra-procedural guidance, and post-procedural inspection will be made evident. 

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
We describe the case of a 61-year-old female with a three-month history of right lower extremity pain and swelling overlying the lateral malleolus. Physical palpation shows the foreign body, later identified as a pine needle, embedded within the deep subcutaneous tissue. On sonographic evaluation, the foreign body is a 1.7cm thin echogenic object with predominantly dirty posterior acoustic shadowing. These sonographic characteristics are consistent with an object of small radius of curvature and a mostly smooth surface. A small incision was made and using forceps and ultrasound guidance the pine needle was successfully extracted.

Conclusion
Subcutaneous foreign-body removal, especially that of organic materials, is ideally done through minimally invasive intervention under ultrasound guidance. Foreign bodies make up a significant percentage of emergency room visits, being especially common in the summer months where bare feet and exposed skin in outdoor recreation are more likely to lead to injury. Furthermore, mis-diagnosis or inadequate removal makes foreign bodies a significant portion of emergency room malpractice suits (3). Under ultrasound foreign bodies generally appear echogenic and sometimes have surrounding hypoechoic areas due to inflammation. The type of posterior acoustic shadowing can sometimes provide the clinician with limited information in regards to the general shape and/or surface characteristics of the foreign body. Ultrasound guided removal of FB reduces tissue damage, minimizes post-procedural complications, and avoids open surgical probing- an option that should be left as a last resort in case of failed object retrieval or visualization on US.