Radiology - Acute indications

  • Background

    A Radiologist is always available if you are uncertain about the most appropriate imaging modality or you have urgent requests, however non-urgent requests should be discussed in business hours (8.30-5pm, Monday to Friday)

    The radiology request card should contain the relevant history as well as the clinical suspicion.

    All patients should have adequate assessment and management before being sent for investigations. A nurse should be available at all times for patients having radiology investigations and medical escort is required for potentially/ unstable patients.

    Upper airway

    •  Retropharyngeal abscess:
      • look for widened prevertebral shadow (normal prevertebral width equal to vertebral body width at C4 level) or neck flexion
    • Inhaled foreign body: 
      • if clinical suspicion that FB in neck or upper resp tract signs
      • rarely, a sharp FB may have perforated ST and imaging of the neck may be indicated
    • Acute epiglotitis:
      • the diagnosis is made clinically NOT radiologically
    See acute upper airway obstruction

    Chest xray (frontal view)

    • Lateral CXR rarely indicated and should be discussed with a consultant
    • Pre-operative CXR NOT to be done routinely at any age.

    Respiratory indications:

    • Infection - to exclude pneumonia 
    • Inhaled foreign body
      • most lodge in intrathoracic tracheobronchial tree.
      • Need films in full inspiration and expiration to demonstrate air trapping or collapse. 
    • Chest trauma
      • for air leak, haemothorax or wide mediastinum. 
      • Rib views rarely indicated.
    • Pneumothorax - full inspiratory films adequate
    • Asthma/ Bronchiolitis - Consider only if: 
      • diagnosis unclear 
      • SEVERE attack - not responding to standard therapy
          possible air leak.
      • NB. Focal signs +/- fever are most likely due to mucus plug and viral illness rather than pneumonia.

    Cardiac indications:

    • Clinical cardiomegaly or heart failure
      • Large thymic shadow is normal under the age of 2 years. 
      • Normal cardio-thoracic ratio 0.5 (infants up to 0.6 ) 
    • Heart murmurs - If careful examination suggests innocent murmur, no need for urgent CXR - but arrange appropriate follow up. 
    • Hypertension - CXR is seldom useful.

    Neonates (<6 wks):

    • Septic screen - CXR indicated unless clear focus elsewhere
    • Respiratory distress - to exclude congestive cardiac failure or cardiomegaly

    Limb xrays & other imaging modalities

    Comparative and Stress Views - rarely necessary and should not be routinely taken. However may be useful for complex fractures (after consultation) if initial xrays unclear (eg elbow)

    Specific Indications/Contraindications:


    • Xray of the suspected fracture as well as the joints above and below if signs and symptoms suggest bone injury.  If in doubt about the site of injury, seek senior help rather than xraying the entire limb. 
      • Follow up films after reduction of a displaced # should be done to assess position.
    • If a fracture is clinically suspected but xrays normal, discuss with consultant and if in doubt treat as if fracture present.
      • Additional views are sometimes useful (eg radial head views) and other fractures (eg stress # or toddler #) might need Bone Scan or CT (these requests should be discussed with ED consultant & orthopaedics and appropriate follow-up arranged). 

    See fractures

    Non accidental injury (to be seen by registrar or consultant)

    • If child > 2yr xrays should be limited to sites of clinically suspected injury. 
    • Complete Skeletal Survey if child < 3 years (not available after-hours unless urgent)
    • ± Bone Scan (if < 3yr) - can complement skeletal survey 
    • Suspect NAI if: 
      • metaphyseal # 
      • marked or unusual epiphyseal separation 
      • # of spine or ribs 
      • unexplained skull # ± intra cranial injury 

    See Non-accidental injury

    Acutely painful hip

    • Plain xrays (AP and frog-leg lateral) will demonstrate slipped upper femoral epiphyses, Perthe's and fractures. 
    • USS/ bone scan may be indicated depending on clinical findings (discuss with specialty team or treating consultant).

    See limping or non-weight bearing child

    Acutely swollen joint

    See acutely swollen joint


    • Early XR often shows no bony abnormality but may have deep soft tissue swelling.
    • Bone scan/MRI will demonstrate an abnormality earlier than XR (needs orthopaedic team input)

    See Bone and joint infection

    Septic Arthritis 

    • Normal XR or Bone scan does not exclude septic arthritis. 
    • Ultrasound may be useful to demonstrate a joint effusion and soft tissue abnormality (discuss with orthopaedic team or treating consultant)

    See Bone and joint infection

    Metabolic disorders 

    • Rickets - XR of one wrist +/- one knee is most useful. 
    • Osteogenesis Imperfecta - very low threshold for xray.

    Pulled Elbow 

    • If injury mechanism and examination suggest radial head subluxation, xray is unnecessary. 

    Abdominal xrays

    Suspected bowel obstruction/ perforation

    • A plain AXR will demonstrate most obstruction (dilated loops).
    • An erect AXR is indicated to exclude perforation 

     Suspected intussusception

    • A normal AXR does not exclude intussusception but is useful to exclude perforation or bowel obstruction in suspected intussusception.

    See intussusception

    Foreign Bodies 

    • Ingested opaque FB requires a single survey AP film (mouth to anus).
    • Routine follow-up films are NOT indicated unless clinical symptoms develop.

    See ingested foreign body

    Suspected Abdominal Mass 

    • Initial investigation - plain AXR and ultrasound, then further as indicated 

    Blunt abdominal trauma 

    • Needs early assessment by General Surgery.
    • CT scan is the best modality for diagnosing intra-abdominal injury.

    Unnecessary AXRs 

    If unsure whether AXR would be helpful - ask consultant or registrar for advice 

    AXR not indicated for: 

    • Vague central abdominal pain 
    • Gastroenteritis 
    • Haematemesis 
    • Pyloric stenosis
    • Uncomplicated appendicitis 
    • Chronic constipation, encopresis or enuresis (in the Emerg. Dept setting)

    Abdominal & pelvic ultrasounds

    If an urgent ultrasound is necessary, the patient should be discussed with the surgeon &/or the treating consultant.

    Specific indications:  

    Suspected intussusception

    • Ultrasound by experienced operators is the diagnostic modality of choice for intussusception.
    • However these patients are potentially unstable and should only be sent for ultrasound after appropriate resuscitation including an IV,  and treatment as well as notifying the surgeons and the treating consultant 

    See intussusception

    Suspected pyloric stenosis

    • Ultrasound is a very sensitive test for pyloric stenosis

    See pyloric stenosis

    Abdominal pain

    • or iliac or pelvic pain in the pubertal female with possible ovarian pathology (requires full bladder), or if potential renal tract obstruction, early ultrasound recommended.
    • Abdominal ultrasound is a useful tool for many other abdominal pain presentations however urgency of the request should be proportional to the symptoms. 

    Urinary tract imaging 

    • Bacteriologically proven first UTI usually requires renal tract US (particularly <4 years old) but only occasionally MCU

    See urinary tract infection 

    Intracranial and skull imaging

    Specific Indications for Skull Xrays (SXR):

    Only indicated in well-appearing children


    •  as part of skeletal survey (more sensitive than Bone Scan for skull fracture) 


    • Craniosynostosis (prematurely fused sutures) accounts for the minority of abnormal skull shapes. A SXR is useful to evaluate sutures but is ideally done via outpatient follow-up (Craniofacial or neurosurgical unit- RCH Deformational head clinic)

    There are no other routine indications for skull XRay and any such requests should be discussed with the treating consultant.

    Specific Indications for CT Brain:

    • The treating consultant should discuss the need for all CT scans. 
    • The Neurosurgical team should be involved before CT for the unwell or potentially unstable patient who may need urgent interventions.

    Head Trauma

    • Useful for rapid diagnosis of suspected intracranial injuries and is the preferred investigation if clinical evidence of intracranial injury. 
    • Clinical deterioration is usually an indication for repeat CT examination. 

    See Head injury   

    Depressed conscious level of unknown cause

    • CT scan is indicated after appropriate stabilising treatment.

    See Coma


    Clinical evaluation is the most important factor in determining the need for imaging. 

    CT scan indications:

    • Abnormal neurological signs. 
    • Unexplained decrease in visual acuity. 
    • Headaches with seizures. 
    • Marked change in behaviour. 
    • Enlarging head
    • Symptoms of raised intracranial pressure. 
    • Increasing frequency of unexplained headaches or new onset of severe or persistent headache

    See headache


    • Persistent abnormal neurological signs/impaired conscious state. 
    • Focal neurological signs or EEG findings. 
    • Failure to respond to anticonvulsant therapy. 
    • Neurocutaneous lesions. 

    See afebrile seizures

    Abnormal Size / Shape Of Skull 

    Clinical examination is usually sufficient to diagnose abnormality of the skull. 

    • Large head - rapidly enlarging head needs imaging-US or CT scan. 
    • Small head - nearly always pathological secondary to abnormal brain growth. Evaluate with CT or MRI scan, which is usually best organised via the managing outpatient physician

    Specific Indications for cranial ultrasound:

    Large head 

    • Rapidly enlarging head with open fontanelle.

    Neurological concerns in neonates/ infants

    • Clinical usefulness will vary depending on size of fontanelle and indications and should be discussed with the radiologist.

    Spinal imaging

    Any investigations other than plain xrays should be ordered in consultation with the treating consultant &/or the appropriate specialty team.

    NB. Down syndrome children have increased risk of C1-2 instability. 

    Specific indications in Trauma:

    Cervical spine

    A normal Spinal Xray series or CT scan will not allow clearance of the neck in the unconscious or uncooperative patient 

    See cervical spine assessment

    Thoraco-Lumbar Spine

    • Children poorly localise the level of the injury, therefore imaging the full length of thoraco-lumbar spine may be necessary (discuss with treating consultant).
    • If neurological signs present do a CT or MRI scan after consultation with Neurosurgery.

    Specific Non-trauma indications:


    • Plain films should include the entire spine

    Potential cord compression

    • Needs discussion with the treating consultant and neurosurgical team.

    Suspected focal vertebral pathology

    • Choice of imaging modality needs discussion with the treating consultant.

    Parent Information