Diagnostic Assessment

The following advice is adapted from NICE Guideline CG128, Autism in under 19s: recognition, referral and diagnosis. [www.nice.org.uk/guidance/cg128/chapter/1-Guidance#recognising-children-and-young-people-with-possible-autism]



Should include the following:

  • A detailed enquiry into the specific concerns raised
  • A medical history
  • Experiences of home life, education and social care
  • History focusing on the developmental and behavioural features specified in the ICD-10 and DSM 5 autism criteria (recommend use of DSM-5 as this supersedes DSM-IV).
  • Observation focusing on the developmental and behavioural features specified in the ICD-10 and DSM 5 autism criteria
  • Physical Examination
  • Assessment for coexisting conditions (if suspected)


Physical Examination

Should include examination for the following:

  • The skin stigmata of neurofibromatosis or tuberous sclerosis (Wood’s light)
  • Physical injury (e.g. due to self-harm or maltreatment)
  • Congenital anomalies
  • Dysmorphic features including micro and macrocephaly.

Do not routinely carry out medical investigations, but where appropriate consider e.g. genetic testing for e.g. specific dysmorphic features, congenital abnormality or learning disability; EEG for suspected epilepsy.


Diagnostic Tools

There is not enough evidence to support the use of any one diagnostic tool over another.  Do not rely on any autism-specific diagnostic tool alone to diagnose autism.

Diagnostic tools do not have to be used as part of an Autism assessment but if you do not use one, you should be making use of the DSM 5 or ICD-10 criteria.

Clinicians may need to consider use of other assessment tools that help the interpretation of the specific autism tools and rating scales, such as an assessment of intellectual ability, or an assessment of receptive and expressive language.  

Recent evidence (NICE Evidence Update 40, April 2013) supports recommendations in CG128 that diagnosis should not result from using one tool alone.


Autism Diagnostic Observation Schedule (ADOS)



Autism Diagnostic Interview – Revised (ADI-R)



Diagnostic Interview for Social Communication Disorders (DISCO)



Developmental, Dimensional and Diagnostic Interview (3di)

[This was in the guidelines, there is a better evidence base for it]


Gilliam Autism Rating Scale (GARS)



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