Foreign body imaging and removal — the data viva

An ACEM-style data viva on the imaging of foreign bodies — a plain X-ray of a nasal button battery (the double-rim sign), a high-frequency ultrasound of a wooden splinter in the soft tissue (the echogenic posterior-shadow sign), a CT of an orbital wooden FB (the hypodense mimicking air), and a slit-lamp fluorescein photograph of a corneal rust ring (the rail-track abrasion of a subtarsal FB). Tests the candidate's ability to recognise the radio-opaque versus the radiolucent, the ocular versus the orbital, and the ED-removable versus the referred.

Prompt

You are presented with four images and four clinical vignettes of foreign bodies in the emergency department. For each, state the most likely object, the imaging modality, and the management.

The data

Case A — a plain X-ray (anteroposterior and lateral) of the nose of a 3-year-old.^[3]^[7]

Feature	Finding
Object	Round, metallic density, resting against the nasal septum
Anteroposterior view	A double-rim (halo) lucency within the disc margin
Lateral view profile	A distinct step-off at the rim
Duration	Three days of retention

Case B — a high-frequency linear ultrasound of the forearm of a 28-year-old who sustained a wooden splinter two weeks ago.^[5]

^[5]| Feature | Finding | |---|---| | Echogenicity | A bright echogenic linear object in the subcutaneous tissue | | Shadowing | A clean posterior acoustic shadow deep to the object | | Surrounding tissue | Localised soft-tissue swelling |

Case C — a non-contrast CT of the orbits of a 40-year-old who sustained a periorbital injury.^[1]

Feature	Finding
Density	A small hypodense linear focus in the inferior orbital soft tissues
Appearance	Reads identically to air or surgical emphysema
Clinical	A persistent discharge from a sinus tract at the entry site

Case D — a slit-lamp fluorescein photograph (cobalt blue) of a 45-year-old with a foreign-body sensation.^[4]

Feature	Finding
Stain pattern	A vertical linear corneal abrasion in the upper half of the cornea
Appearance	Parallel vertical lines of stain uptake (the rail-track sign)
Lid	An upper lid that was not everted at the first visit

^[4]

References9Show

[1]Carneiro BC, Cruz IAN, Chemin RN, et al. Multimodality Imaging of Foreign Bodies: New Insights into Old Challenges. RadioGraphics, 2020.PMID 33136481
[2]Chaulagain U, Gyawali S, Pokhrel KM, et al. Missed Wooden Perineum Foreign Body Leading to Extensive Necrotizing Soft Tissue Infection: A Case Report. Clinical Case Reports, 2026.PMID 41550391
[3]Heilig Y, Tsarfati Y, Gete M, et al. Long-term outcomes following nasal button battery foreign body injuries in children: a 10-year retrospective analysis of 45 patients. International Journal of Pediatric Otorhinolaryngology, 2026.PMID 41985339
[4]Ng SM, Leslie L, Tzang CC, et al. Antibiotic prophylaxis for corneal abrasion Cochrane Database Syst Rev, 2025.PMID 41017778
[5]Osborne K, McLean TJ, Heiner JD, et al. Special Forces Medics Ability to Identify Wooden Foreign Bodies by Point-of-Care Ultrasound J Spec Oper Med, 2025.PMID 39621007
[6]Kavanagh KT, Litovitz T Miniature battery foreign bodies in auditory and nasal cavities JAMA, 1986.PMID 3951081
[7]Meyer TJ, Grunz JP, Taeger J, et al. Systematic analysis of button batteries', euro coins', and disk magnets' radiographic characteristics and the implications for the differential diagnosis of round radiopaque foreign bodies in the esophagus International Journal of Pediatric Otorhinolaryngology, 2020.PMID 32032915
[8]Rosenberg PH, Veering BT, Urmey WF Maximum recommended doses of local anesthetics: a multifactorial concept Regional Anesthesia and Pain Medicine, 2004.PMID 15635516
[9]Tan C, Rayner M, Eiselen C, et al. Ophthalmic trauma: First-line management in primary care. Australian Journal of General Practice, 2026.PMID 42392210