Wrist PA Oblique is a radiography positioning projection of the Upper Extremity. Seated with wrist rotated 45 degrees, radial side raised. SID 40". The centering point is located midcarpal area, rotated 45 degrees. The central ray is perpendicular to the midcarpal area. Image-quality criteria include wrist shown in 45-degree oblique with minimal overlap, radius, ulna, carpals, and proximal metacarpals included. A sample technique is 66 kVp with DR 0.9 or CR 2 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- Distal radius and ulna.
- Trapezium and scaphoid, the main carpals shown; also trapezoid, lunate, and triquetrum.
- Proximal metacarpals.
Patient preparation
- WARNING: with possible spinal injury or severe trauma, do not attempt to move the patient; do not rotate a severely injured part or remove splints (Bontrager). Merrill's: do not attempt true AP or lateral positioning of a severely injured limb; take two projections 90 degrees apart, moving it as little as possible, and move the IR and tube if the patient cannot reach the position.
- Verify patient identity using two identifiers.
- Remove watches, bracelets, and radiopaque items from the wrist.
- Seat the patient at the end of the table.
- Place forearm on table. Rotate wrist 45 degrees.
- Raise the radial (thumb) side 45 degrees on a support, or partially flex the fingers so the fingertips rest lightly on the IR.
Position & centering point
Midcarpal area, rotated 45 degrees.
Central ray
Perpendicular to the midcarpal area.
Exposure / technique
- kVp
- 66
- mAs
- DR 0.9 / CR 2
- SID
- 40" (102 cm)
- Notes
- Tabletop technique. Radial side raised 45 degrees. Sample technique: DR 0.9 / CR 2 mAs at 66 kVp, 40 in SID, for a 4 cm part. Adjust for your equipment.
kVp and mAs are sample values. Use caution when applying them in your department.
Image-quality criteria
- Wrist shown in 45-degree oblique with minimal overlap.
- Radius, ulna, carpals, and proximal metacarpals included.
- Trapezium and scaphoid well visualized, with only slight superimposition of other carpals on their medial aspects.
- Bone trabeculae and soft tissue sharp, no motion blur.
- Collimation: 2.5 inches distal and proximal to wrist joint.
Common errors
- 1 Wrist rotated less than 45 degrees minimizes the oblique.
- 2 Not a true 45-degree oblique: ulnar head should be partly superimposed by the distal radius.
- 3 CR not at the midcarpal area.
Clinical indications
- Fractures of the distal radius or ulna, the radial or ulnar styloid process, or individual carpal bones.
- Suspected wrist joint arthritis or degenerative changes.