DRSABCDE of CXR Interpretation

Chest X-Rays (CXR) are routine investigation in clinical practice and consequently it is important for medical students and clinician’s alike to know how to interpret them. There are many approaches to CXR interpretation, each trying to ensure that key abnormalities are identified and no area is overlooked.

Many people would be familiar with the ABC method to interpreting CXRs.

  • Airways
  • Breathing & Bones
  • Circulation

This is a simple way of approaching CXR, and it works for many people, however some people still struggle using this approach. In light of this, a colleague of mine Matthew Lumchee, developed an approach that was both more encompassing but also familiar.

DRSABCD is a familiar acronym for those who have undertaken First Aid/Basic Life Support courses. Now DRSABCDE can used as a simple, yet comprehensive, approach to CXR interpretation.

D – Details

Before you even begin interpreting a CXR you should have the correct details. This includes;

  • Patient name, age / DOB, sex
  • Type of film – PA or AP, erect or supine, correct L/R marker, inspiratory/expiratory series
  • Date and time of study

R – RIPE (assessing the image quality)

Next up, how “ripe” is the image. That is, what is the technical quality of the film?

  • Rotation – medial clavicle ends equidistant from spinous process
  • Inspiration – 5-6 anterior ribs in MCL or 8-10 posterior ribs above diaphragm, poor inspiration?, hyperexpanded?
  • Picture – straight vs oblique, entire lung fields, scapulae outside lung fields, angulation (ie ’tilt’ in vertical plane)
  • Exposure (Penetration) – IV disc spaces, spinous processes to ~T4, L) hemidiaphragm visible through cardiac shadow.

S – Soft tissues and bones

In CXR interpretation it is common to leave soft tissues until the end.

  • Ribs, sternum, spine, clavicles – symmetry, fractures, dislocations, lytic lesions, density
  • Soft tissues – looking for symmetry, swelling, loss of tissue planes, subcutaneous air, masses
  • Breast shadows
  • Calcification – great vessels, carotids

A – Airway & mediastinum

  • Trachea – central or slightly to right lung as crosses aortic arch
  • Paratracheal/mediastinal masses or adenopathy
  • Carina & RMB/LMB
  • Mediastinal width <8cm on PA film
  • Aortic knob
  • Hilum – T6-7 IV disc level, left hilum is usually higher (2cm) and squarer than the V-shaped right hilum.
  • Check vessels, calcification.

B – Breathing

  • Lung fields
    • Vascularity – to ~2cm of pleural surface (~3cm in apices), vessels in bases > apices
    • Pneumothorax – don’t forget apices
    • Lung field outlines – abnormal opacity/lucency, atelectasis, collapse, consolidation, bullae
    • Horizontal fissure on Right Lung
    • Pulmonary infiltrates – interstitial vs alveolar pattern
    • Coin lesions
    • Cavitary lesions
  • Pleura
    • Pleural reflections
    • Pleural thickening

C – Circulation

  • Heart position –⅔ to left, ⅓ to right
  • Heart size – measure cardiothoracic ratio on PA film (normal <0.5)
  • Heart borders – R) border is R) atrium, L) border is L) ventricle & atrium
  • Heart shape
  • Aortic stripe

D – Diaphragm

  • Hemidiaphragm levels – Right Lung higher than Left Lung (~2.5cm / 1 intercostal space)
  • Diaphragm shape/contour
  • Cardiophrenic and costophrenic angles – clear and sharp
  • Gastric bubble / colonic air
  • Subdiaphragmatic air (pneumoperitoneum)

E – Extras

  • ETT, CVP line, NG tube, PA catheters, ECG electrodes, PICC line, chest tube
  • PPM, AIDC, metalwork

Why not grab a copy of our Basic CXR Interpretation flow chart and put it up in your ward or clinic.

References

Normal CXR Labelled

DRSACBCDE CXR interpretation

Print Friendly

Comments

  1. Duncan says

    I am not a fan of the ‘mangle the subject until it fits the acronym’ approach. Non-intuitive acronyms are, well, non-intuitive.

    I can’t see why there isn’t a good reason to have an automatic popup (easily closed) to accompany any imaging on any modern PACS system. So when you bring up the paediatric elbow images, first you get a popup which says “This XRAY was taken TODAY for JOHN SMITH”, then you have a nonintrusive and easily closed handy visual summary *of paediatric elbow radiograph interpretation* with information like ossification centres, relevance of anterior humeral line, common missed findings (if that’s not an oxymoron). Similarly for chest films, abdo films and whatever else. Deeper links can clarify more complex topics, and even link to an atlas of variants. Radiologists can deactivate it for their workstation / account if they feel it offends their encyclopaedic knowledge (or tailor it to have stuff more useful to them, like distances and rare pathology for uncommon studies).

    Failing that, flipcharts or posters beside the PACS viewers are a distant second place. But the need for an acronym is for when you DON’T have the information accessible and need to remember it.

    • says

      Thanks for your comments Duncan. The mnemonic was merely meant as a way of learning an approach to X-Rays for medical students. In general, I think that the more ways someone can learn material, is only going to help in the long run. The Mnemonic is not perfect, but we tried to bring back something familiar to medical students, that is DRSABCD from basic life support, to aid in memorising at least the core components of CXR interpretation.

      Your points about the visual details and summaries integrated into the PACS system would be great. Useful for both novices and radiologists alike. Unfortunately knowing the public health system I think it’s still a while off.

      The poster was to just play on the similarity to the Basic Life Support mnemonic.

      If you have an approach to CXR that you find useful for new learners, I would be happy to hear it.

      Cheers,
      Aaron

      • Duncan says

        I’m not disputing that having a system that is inclusive is a good idea, or that repetition and reinforcement will help the learner -- but when the acronym is too contrived it is harder to remember, and when multiple subjects share the same acronym the value is probably diluted rather than augmented.

        When I was a student, I was taught the ‘correct’ order, and we repeatedly had to present radiographs to the group using that metric. Name, date, subject, orientation, position, adequacy then proceeding on to the actual image. I would in no way endorse that approach. My approach for new learners is more that of:
        Who? -- correct patient
        When? -- correct day
        Why? -- what is the indication for the test / what are we looking for
        What? -- what is the image of

        then consider what systems are present in the image, and identify them, e.g.
        Chest radiograph
        -- respiratory (so look for airways, parenchyma, pleura)
        -- cardiac (so look for cardiac contour, size, shape)
        -- vascular (so look for great vessel contours)
        -- GI (oesophagus, stomach)
        -- skeletal (all bones visible)
        -- and so on… it doesn’t need to be this exact system -- just any system that includes everything. So you can do ABCDE (airways, bones, circulation, digestion, endocrine) or VINTMEDATI, or whichever you find easiest to remember
        Lastly, consider the things that contribute to mistakes
        -- did I stop looking after I found one abnormal finding? Do I need to complete my system?
        -- what are the commonly missed things in this situation/imaging modality?
        -- am I tired / bored / distracted?
        -- how do the clinical findings and the radiographic findings correlate?
        -- have I examined the patient properly (ED juniors, a shoulder x-ray is not a substitute for an examination)

  2. says

    great mnemonic! I learned a similar variation, with 2 minor changes: B is for bones, and it goes to F for lung Fields. the benefit is that it forces you to look for the more subtle aspects prior to getting to the meat (eg pneumonia). similar to most of the ways to interpret ECGs where you look at rate rhythm axis and intervals prior to checking for ST/T changes

  3. says

    I don;t mind mnemonics like this -- cos at 3am when I am hungry/tired/stressed I need a robust method to rely on. I use ABCDE for my trauma -- so why not for my trauma CXR?

    But the point on visual aids incorporated into PACS is a good one. Reckon there’s a few bob to be made there if someone can work out a way of introducing relevant, specific and essential info..

    Just so long as it’s not advertising, and can be easily blocked or removed…

    • says

      Thanks Tim. I was thinking visual aids would be great and was trying to remember where I saw a good example of it. BioDigitalHuman is a web3D anatomy viewer and I reckon something similar to their interface would be useful in radiology -- http://yfrog.com/esdxcrxj

      Rather than selecting a piece of anatomy like above, when submitting an imaging request (electronically ideally), tags could be added (e.g. chest x-ray, respiratory problem, heart failure history, trauma, etc), so that later the relevant notes appear to the viewer. Like in BioDigitalHuman you should also be able to search for common radiological findings of certain conditions, if clinically indicated within PACS.

      Just my two cents on the concept.

      Cheers,
      Aaron

  4. frank brodzik says

    Nice review…I teach an “outside in” approach and emphasize itd similarity to the physical examination of the chest. We observe a patient before we palpate before we percuss the chest before we auscultate…we can view a radiograph in the same way. Looking at each layer for signs of pulmonary disease then moving to a deeper layer…I find this method easier for students to learn and it reinforces the supremacy of the physical examination.

Comments