The lateral decubitus radiograph is an additional projection for assessing the pediatric abdomen. This view is ideal for displaying free gas 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 artifact 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