EM · Plain radiograph interpretation (approach)
X-ray interpretation in the emergency department — the systematic approach
Also known as X-ray interpretation · Plain film interpretation · CXR interpretation · MSK radiograph interpretation
The systematic approach to plain radiography for the emergency medicine trainee — the technical-quality check (projection, penetration, rotation, inspiration), the chest radiograph method (airway, bones, cardiac, diaphragm, effusions, fields, tubes and lines), the musculoskeletal ABCCS method (adequacy and alignment, bones, cartilage and joints, soft tissue, summary), the Salter-Harris paediatric physeal classification, the fracture descriptors (transverse, oblique, spiral, comminuted, buckle, greenstick), the Ottawa ankle and knee rules and the NEXUS and Canadian C-spine rules, and the normal-vs-abnormal-vs-artefact differential. The image-to-action thresholds — free gas under the diaphragm triggering broad-spectrum antibiotics, the misplaced nasogastric tube withdrawn before any feed, hip fracture managed with a fascia-iliaca block. ACEM-primary, globally tagged.
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Target exams
Red flags
- A nasogastric tube tip lying in a main bronchus is a never-event — withdraw and reposition before any feed or medication is given
- A positive posterior fat pad sign on an elbow radiograph is pathognomonic of an occult intra-articular fracture, even when no fracture line is visible
- A skin fold can mimic a pneumothorax — but a supine trauma patient with a deep sulcus sign, hypoxia and hypotension has a tension pneumothorax until proven otherwise
- A normal radiograph does not exclude disease — the early scaphoid fracture, pulmonary embolism and early osteomyelitis are radiographically occult
- A spiral long-bone fracture in a non-ambulant child, or a posterior rib fracture at any age, is a non-accidental injury until safeguarding work-up excludes it
Meet the patient
A 24-year-old is rolled in from a high-speed motor-vehicle crash — intubated, a right internal-jugular line in, a pelvic binder on. The portable supine AP chest film is handed to you as part of the primary survey, and the registrar asks: "What does it show, and what do we do next?"[1]
That question is the whole topic. The film is a two-dimensional shadow of a three-dimensional patient lying in front of you, rotated, under-penetrated, magnified — and the only thing standing between a clean read and a never-event is the sequence you run. Pattern recognition finds the obvious; a system finds the tube sitting in the right main bronchus, the deep sulcus of a tension pneumothorax, and the widened mediastinum of a traumatic aortic injury.[1]
Etymology for the viva: radiograph comes from the Latin radius, "a ray" or the spoke of a wheel — the beam that passes through the patient and strikes the detector. Röntgen named his 1895 discovery X-Strahlen, "X-rays", the X standing for the unknown. The word outlived the mystery; the method is what you are examined on.[8]
The mantra: quality first, compartments in order, state the finding and the next action — the method is the mark, not the diagnosis.[1]
References11ShowHide
- [1]Stiell I, Wells G, Laupacis A, et al. Multicentre trial to introduce the Ottawa ankle rules for use of radiography in acute ankle injuries. Multicentre Ankle Rule Study Group BMJ, 1995.PMID 7663253
- [2]Stiell IG, Greenberg GH, Wells GA, et al. Prospective validation of a decision rule for the use of radiography in acute knee injuries JAMA, 1996.PMID 8594242
- [3]Seaberg DC, Yealy DM, Lukens T, et al. Multicenter comparison of two clinical decision rules for the use of radiography in acute, high-risk knee injuries Ann Emerg Med, 1998.PMID 9656942
- [4]Hoffman JR, Mower WR, Wolfson AB, et al. Validity of a set of clinical criteria to rule out injury to the cervical spine in patients with blunt trauma. National Emergency X-Radiography Utilization Study Group N Engl J Med, 2000.PMID 10891516
- [5]Stiell IG, Wells GA, Vandemheen KL, et al. The Canadian C-spine rule for radiography in alert and stable trauma patients JAMA, 2001.PMID 11597285
- [6]Kappelhof B, Roorda BL, Poppelaars MA, et al. Occult Fractures in Children with a Radiographic Fat Pad Sign of the Elbow: A Meta-Analysis of 10 Published Studies JBJS Rev, 2022.PMID 36326720
- [7]Roth OS, Gupta A, Adebayo T, et al. Risk Factors and Surgical Sequelae of Physeal Arrest in Pediatric Salter-Harris III and IV Medial Malleolus Fractures J Pediatr Orthop, 2026.PMID 41230683
- [8]Sethole KM, Mshunqane N, Kekana M Checklists for interpreting chest radiographs: a scoping review protocol Syst Rev, 2023.PMID 37649115
- [9]Abosayed AK, Dayem AYA, Shafik I, et al. Prognostic value of free air under diaphragm on chest radiographs in correlation with peritoneal soiling intraoperatively Emerg Radiol, 2023.PMID 36515771
- [10]Tahir A, Naji O, Khawar H, et al. Torus fractures - diagnosis and management Br J Hosp Med (Lond), 2024.PMID 38815969
- [11]O'Connell F, Ong J, Donelan C, et al. Emergency department approach to gastric tube complications and review of the literature Am J Emerg Med, 2021.PMID 32736966