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.

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 changes management ².

Indications

This view is valuable in visualizing gas-fluid levels and free gas in the abdominal cavity as it allows the assessment of ascites, perforation, intra-abdominal masses, ileus, or postoperative complications.

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)
• centering point
  • 5 cm above the iliac crest at the midsagittal plane
• collimation
  • superiorly to include the hemidiaphragms
  • 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 

This view is often done in teaching hospitals where a plethora of teams might 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, therefore a PA erect view may not be possible, for these cases consider a lateral decubitus projection. It is paramount you include the hemidiaphragms in this projection, to aid assessment of free gas in the abdominal cavity. Ensure that you then cover the lower portion of the abdomen in the supine AP projection.