Abdomen (PA erect view)

The PA erect abdominal radiograph is often obtained in conjunction with the AP supine abdominal view in the acute abdominal series of radiographs. When used together it is a valuable projection in assessing air fluid levels, and free air in the abdominal cavity.

The erect abdominal radiograph has virtually disappeared from clinical practice in the United Kingdom, with studies dating back to the 1980s affirming that the erect projection rarely changed management ².

Patient position

• the patient is standing, with ventral abdomen toward the image detector
• no rotation of shoulders or pelvis
• should include the entire transverse width of the patient (if possible; if not, two radiographs may be obtained)
• hands can be placed around the detector or on top 

Technical factors

• posteroanterior projection
• suspended inspiration (departmentally dependent)
• centring point
  • 5 cm above the iliac crest at the midsaggital plane
• collimation
  • superiorly to include the diaphragms
  • to include as much of the abdomen as possible 
  • lateral to the skin margins
• orientation  
  • portrait
• detector size
  • 35 cm x 43 cm or 43 cm x 35 cm
• exposure
  • 70-80 kVp
  • 30-50 mAs
• SID
  • 100 cm
• grid
  • yes

Image technical evaluation

• lateral abdominal wall should be included
• inferior pubic rami should be included inferiorly
• the diaphragm must be included superiorly
• the abdomen should be free from rotation with symmetry of the:
  • ribs (superior)
  • iliac crests (middle)
  • obturator foramen (inferior)
• no blurring of the bowel gas due to respiratory motion

Practical points 

Often this view is done in teaching hospitals where a plethora of teams will need to interpret an acute abdominal series. Patients who truly require an acute abdominal series will be in a lot of pain and quite unwell, a PA erect view may not be possible, these cases consider a lateral decubitus projection (see figure 2). It is paramount you include the diaphragms in this projection, to aid assessment of free gas in the abdominal cavity. Often you will cover the lower portion of the abdomen in the supine AP projection.