Pediatric abdomen (lateral decubitus view)

Last revised by Ian Bickle on 15 Oct 2023

The lateral decubitus radiograph is an additional projection for assessing the pediatric abdomen. This view is ideal for displaying free air in the abdomen and/or if the patient is unable to lie supine 1. As radiation dose is an important consideration for pediatric imaging, the lateral decubitus view is not often performed; although this will vary based on the department. 

  • patient is in a left lateral decubitus position with both knees bent up
  • ensure no rotation of hips and shoulders
  • remove any radiopaque items (e.g. ECG dots, diaper, shiny decorative clothing)
  • take the x-ray in full inspiration
  • posteroanterior projection
    • ​in order to reduce the radiation dose to radiosensitive organs 1
  • centering point
    • the midsagittal plane (xiphisternum) at the level of the iliac crest
  • collimation
    • laterally to the lateral abdominal wall
    • superior to the diaphragm
    • inferior to the inferior pubic rami
    • it is not advised to collimate too tightly laterally in case of missing bowel loops and/or organs 1
  • orientation
    • portrait
  • detector size
    • will vary depending on the child's body habitus
  • exposure 2
    • 60-75 kVp
    • 2-10 mAs
  • SID
    • 100 cm
  • grid
    • ​if patient thickness is above 10 cm, use of a grid is advisable 2
  • include the
    • lateral abdominal wall
    • inferior pubic rami inferiorly
  • must include the diaphragm superiorly
  • the abdomen should be free from rotation with symmetry of the:
  • no blurring of the bowel gas due to respiratory motion
  • it may be useful to position the patient so that they can see their parents in order to reduce anxiety
  • pediatric patients may feel uncomfortable when bony landmarks are felt for, therefore an appropriate explanation to the patient beforehand is ideal for improving patient comfort
  • to achieve sufficient inspiration, using child-appropriate language will be useful
    • e.g. 'breathe in as if you are about to go diving underwater!', 'breathe in as if you are about to blow out a birthday candle!'

It is important for the image to be free from movement artefact and rotation to avoid repeated x-rays.

  • it may be necessary for the parent or radiographer to stand with the patient or hold them in position
  • sometimes it is only necessary to keep the child's arms away from the abdominal area; in these cases, asking the child to hold onto something to their side (e.g. toy, mother's hand, pole) may be useful. 
  • techniques will vary based on the department

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