P2.M251: Ricochet: Case of a Foreign Body Folly​

Introduction: Projectile foreign bodies (FB) often go undiscovered upon initial wound examination, even in cases with highly suggestive history and physical exam findings. Detection of FBs is drastically increased through early use of imaging modalities, such as point-of-care ultrasound (POCUS) and radiology performed ultrasound (RADUS). Here, we present the unique case of an elusive bullet fragment foreign body whose discovery followed a prolonged, clinical course.

Case Description: An 11-year-old female presented to the emergency department (ED) with concern of a “facial laceration” on her right cheek. She was shooting a .22-gauge rifle with family using glass bottles as targets when a presumed glass shard ricocheted back and struck her cheek. A 1.2 cm (about 0.47 in) linear laceration was present on the right cheek, and no other injuries were observed. Wound exploration and suture repair were performed with no significant findings. No imaging was performed.

Patient returned to the emergency department 16 days later with significant facial swelling. A small abscess was observed in the right cheek, and limited bedside soft tissue ultrasound showed a “small pocket of superficial fluid.” The abscess was drained, cleaned, and re-closed.

5 days after the second ED visit, the patient returned due to parental concerns of progressive enlargement of right cheek laceration and increasing pain. Limited focused soft-tissue bedside ultrasound performed by emergency medicine physician showed soft-tissue fluid collection, less concerning for abscess. A radiology ultrasound was ordered and demonstrated 3 or 4 possible crescentic echogenic foreign bodies, consistent with the patient’s initial history and physical exam findings. Surgical removal performed the following day revealed a solitary bullet fragment foreign body measuring 10x6 mm (about 0.24 in).

Discussion: Foreign bodies from projectiles are often difficult to detect via unassisted wound exploration. Foreign bodies that are not localized and removed promptly are more likely to lead to infection, inflammation, and permanent scarring. This case highlights the importance of identifying foreign bodies on the initial medical visit via appropriate imaging modalities. It additionally emphasizes the flaws of relying on history and physical exams alone. In this case the consequence was delayed diagnosis and removal of the foreign body. It further underscores the difficulty of identifying foreign bodies with ultrasound and the misinterpretation of foreign bodies on ultrasound even by radiologists.

Conclusion: This case highlights the importance of identifying foreign bodies on the initial medical visit via appropriate imaging modalities. When using POCUS for the evaluation of foreign bodies, it can be difficult to identify very small foreign bodies. One must evaluate for artifacts and abscess (halo sign). These are more consistently seen compared to the foreign body itself. It is paramount to have a low threshold to obtain additional imaging studies (CT, X-RAY, RADUS) if there is any diagnostic uncertainty.