Wrist PA in Ulnar Deviation is a radiography positioning projection of the Upper Extremity. Seated, forearm extended on IR, hand deviated toward ulnar side. SID 40". The centering point is located scaphoid, about 3/4 inch (2 cm) distal and medial to the radial styloid process, with the hand in ulnar deviation. The central ray is perpendicular to the IR, centered to the scaphoid. Image-quality criteria include scaphoid, trapezium, and trapezoid opened up on the radial side of the wrist, first through fifth metacarpal bases included. The SID is 40 inches (102 cm).
Anatomy demonstrated
- Scaphoid, lunate, and triquetrum clearly visible.
- Scaphoid with reduced foreshortening (Merrill's).
- Capitate, hamate, and trapezoid.
- Trapezium and metacarpal bases.
- Distal third of radius and ulna.
- Spaces between adjacent carpals open.
Patient preparation
- WARNING: if wrist trauma is possible, do not attempt this position before a routine wrist series has been completed and evaluated to rule out a distal forearm or wrist fracture (Bontrager).
- If wrist trauma is possible, take this only after the routine wrist series has been checked for a distal forearm or wrist fracture.
- Verify patient identity using two identifiers.
- Remove watches, bracelets, and radiopaque items from the arm.
- Seat the patient at the end of the table, wrist and hand on the IR, palm down, shoulder, elbow, and wrist on the same horizontal plane.
- Position the wrist as for a PA, hand and wrist aligned with the long axis of the IR, scaphoid centered to the CR.
- Without moving the forearm, turn the hand toward the ulnar side as far as the patient can tolerate, without lifting or rotating the distal forearm.
Position & centering point
Scaphoid, about 3/4 inch (2 cm) distal and medial to the radial styloid process, with the hand in ulnar deviation.
Central ray
Perpendicular to the IR, centered to the scaphoid.
Exposure / technique
- kVp
- N/A
- mAs
- N/A
- SID
- 40" (102 cm)
- Notes
- Tabletop technique. No grid required. Bontrager lists 60 to 70 kV analog and 60 ± 5 kV digital; neither book's chart prints an mAs for this projection.
Image-quality criteria
- Scaphoid, trapezium, and trapezoid opened up on the radial side of the wrist.
- First through fifth metacarpal bases included.
- Distal radius and ulna visible, with minimal superimposition at the distal radioulnar joint.
- Maximum ulnar deviation, shown by the angle between the ulna and the fifth metacarpal.
- Bone trabeculae sharp, no motion blur.
- Collimation: 2.5 inches distal and proximal to the wrist joint.
Common errors
- 1 Too little ulnar deviation, so the scaphoid is not opened up.
- 2 Distal forearm lifted or rotated while deviating the hand, so the wrist is rotated.
- 3 CR not centered to the scaphoid.
- 4 Motion blur from patient movement during the exposure.
- 5 Insufficient ulnar deviation leaves the scaphoid foreshortened.
- 6 Radial deviation opens the ulnar side of the wrist, not the scaphoid side.
- 7 CR not at the scaphoid.
- 8 Pronation or supination changes the wrist angle.
Clinical indications
- Possible scaphoid fracture.
- Carpal bone fracture evaluation.