Pathology Demonstrated:

  • Abnormal masses, air-fluid levels, and possible accumulations of intraperitoneal air are demonstrated. (Small amounts of free intraperitoneal air are best demonstrated with chest technique on erect PA chest.)
  •  Important: Patient should be on side a minimum of 5minutes before exposure ( to allow air to rise or abnormal fluids to accumulate); 10 to 20 minutes is preferred, if possible, for best visualization of potentially small amounts of interperitoneal air.
  • Left lateral decubitus best visualized free intraperitoneal air in the area of the liver in the right upper abdomen away from the gastric bubble.

Technical Factor:

  • IR size 35 x 43cm (14 x 17 inches), crosswise to the table (lengthwise with the patient)
  • Moving or stationary grid
  • 70 to 80 kV range


  • Place arrow or other appropriate marker to indicate "up" side.


  • Use gonadal shielding on males.

Patient Position:
AP abdomen, left lateral decubitus position

  • Lateral recumbent on radiolucent pad, firmly against table or vertical grid device (with wheels on cart locked so as not to move away from table)
  • Patient on frm surface, such as a cardiac or back board, position under the sheet to prevent sagging and anatomy cutoff
  • Knees partially flexed, one on top of the other, to stabilized patient
  • Arms up near head; clean pillow provided

Part Position:

  • Adjust patient and cart so that center of IR and CR are approximately 2 inches (5cm) above level of iliac crest (to include diaphragm). Promiximal margin of cassette will be approximately at level of axilla.
  • Ensure no rotation of pelvis or shoulders.
  • Adjust height of cassette to center midsagital plane of patient to center of IR, but ensure that upside of abdomen is clearly included on the IR.

Central Ray:

  • CR horizontal, directed to center of IR, at about 2 inches (or 5cm) above level of illiac crest; use of a horizontal beam to demonstrate air-fluid levels and free intraperitoneal air
  • Minimum SID of 40 inches (100cm)


  • Collimate on four sides; do not cut off upper abdomen.


  • Make exposure at end of expiration.