Wrist (PA view)

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The PA wrist view is part of a three view series of the wrist and carpal bones. Although performed PA the view can often be referred to an AP view.

Indications

The PA wrist radiograph is requested for myriad reasons including but not limited to trauma, suspected infective processes, injuries the distal radius and ulna, suspected arthropathy or even suspected foreign bodies.

What is probably more useful is remembering that a PA wrist radiograph will not rule out a forearm fracture given the limited coverage (for this, one would request a forearm series).

Patient position

  • patient is seated alongside the table
  • the affected arm if possible is flexed at 90° so the arm and wrist can rest on the table
  • the affected hand is placed, palm down on the image receptor
  • shoulder, elbow, and wrist should all be in the transverse plane, perpendicular to the central beam
  • the wrist and elbow should be at shoulder height which makes radius and ulna parallel (lowering the arm makes radius cross the ulna and thus relative shortening of radius)

Technical factors

  • posteroanterior projection
  • centering point
    • mid carpal region
  • collimation
    • laterally to the skin margins
    • distal to the midway up the metacarpals
    • proximal to the include one-quarter of the distal radius and ulna
  • orientation  
    • portrait
  • detector size
    • 18 cm x 24 cm
  • exposure
    • 50-60 kVp
    • 3-5 mAs
  • SID
    • 100 cm
  • grid
    • no

Image technical evaluation

  • there is only minor superimposition of the metacarpal bases
  • the articulation between the distal radius and the ulna is open or has little superimposition.
  • the concavity of the metacarpal shafts is equal .

Practical points

Wrist radiographs are very common in emergency departments; they are often associated with FOOSH injuries and be quite painful.

Due to the non-urgent nature of a "?fractured wrist", patients will often be triaged to a lower category and left waiting for longer than multi-trauma patients; an understandable reality of emergency departments.

It is important to remember this when examining your patient, and it is easy to forget that simply lifting your hand up and placing it on an image receptor could result in substantial pain. More often than not, the pain has not been addressed yet. Offer to move things around to assist in positioning, simple things like lowering/raising the table can go a long way and result in a better experience for the patient.

It is also possible to achieve the PA wrist with the patient supine in bed, by simply following the basic positioning principles, the image receptor can be placed next to the patient on the bed under the affected wrist.