Abdomen (AP supine view)

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The AP supine abdominal radiograph can be performed as a standalone projection or as part of an acute abdominal series, depending on the clinical question posed, local protocol and the availability of other imaging modalities.

Indications

This view is useful in assessing abdominal pathologies, including bowel obstructions, calcifications and neoplastic changes. It is also used as a scout/baseline image for contrast studies of the abdomen (i.e. small bowel follow-through).

Patient position

  • the patient is supine, lying on his or her back, either on the x-ray table (preferred) or a trolley
  • patients should be changed into a hospital gown, with radiopaque items removed (e.g. belts, zippers, buttons)
  • the patient should be free from rotation; both shoulders and hips equidistant from the table/trolley
  • the x-ray is taken on full inspiration
    • this causes the diaphragm to contract, hence compressing the abdominal organs, allowing all abdominal contents to be visualized on a single image

Technical factors

  • AP projection
  •  centering 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

Image technical evaluation

  • if possible, the diaphragm should be included superiorly
  • the abdomen should be free from rotation with symmetry of the:
  • 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.