Abdomen (oblique view)

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AP oblique supine radiograph is a projection often used in barium studies and foreign body localisation.

Indications

This view is normally performed when localising foreign bodies or lines within the abdominal cavity. Additionally, the oblique abdominal series can be utilised in the assessment of the upper intestinal tract during barium studies.

Patient position

  • the patient is laying 30 degrees either LAO or RAO, often on a 30-degree wedge to ease of positioning 
  • patients should be changed into a hospital gown, with radiopaque items (e.g. belts, zippers) removed
  • the x-ray is taken in full inspiration

Technical factors

  • AP oblique  projection
  •  centring point
    • the midsagittal place (equidistant from each ASIS) at the level of the iliac crest
  • collimation
    • laterally to the lateral abdominal wall
    • superior to the diaphragm
    • inferior to the inferior pubic rami
  • orientation
    • portrait
  • detector size
    • 35 cm x 43 cm
  • exposure
    • 70-80 kVp
    • 30-120 mAs; AEC should be used if available
  • SID
    • 100 cm
  • grid
    • yes

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Image technical evaluation

  • lateral abdominal wall should be included
  • inferior pubic rami should be included inferiorly
  • if possible, the diaphragm should be included superiorly
  • adequate rotation can be confirmed via the presence of the 'Scotty dog' sign of the lumbar spine 
  • no blurring of the bowel gas due to respiratory motion

Practical points

For larger patients, it may be necessary to perform two x-rays using a landscape orientation of the detector to include the entire abdomen.

Exposure will need to be adjusted according to the imaging system (CR or DR) and patient size. Where possible mAs should be manipulated to ensure adequate image density and appropriate image contrast.