Pediatric abdomen (lateral decubitus view)

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 position

• 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

Technical factors

• 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

Image technical evaluation

• 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:
  • ribs (superior)
  • iliac crests (middle)
  • obturator foramen (inferior)
• no blurring of the bowel gas due to respiratory motion

Practical points

• 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!'

Immobilization techniques

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