Autism diagnostic process

CORONAVIRUS UPDATE – July 2021: The majority of our assessments are now being carried out online. We are offering a limited number of face-to-face appointments in line with the latest Covid-19 guidance. The waiting times for face-to-face appointments are likely to be longer than for online assessments.  


BASS Autism Services for Adults offer a diagnostic service, accessible via GP and secondary care referral. We cover Bristol, South Gloucestershire, North Somerset and Bath and North East Somerset. We also accept referrals on a cost-by-case basis from other areas. Information and advice for GPs and referrers is available here 

The assessment process

Once your referral is accepted you will be sent a letter to confirm that we have received it and a self-assessment questionnaire. Once you have returned this questionnaire you will be offered a triage appointment when you get to the top of the waiting list.

Triage appointment

When you arrive at the triage appointment you will meet with two experienced clinicians to discuss your needs and the difficulties that led to your referral. The appointment will take approximately 75 minutes. At the end of the appointment we will give recommendations for next steps.

Possible outcomes of the appointment are:

  • Recommendation that you should be put forward for a comprehensive assessment by our service. This will mean that you are added to our waiting list for a complex assessment.
  • Recommendation that the difficulties discussed are not related to a diagnosis of autism.  This will mean that you are discharged from our service. In this situation we make every effort to recommend other services that better meet your needs if this is appropriate.

Complex Assessment

If the outcome of the triage appointment is that you are added to the waiting list for a complex assessment the next steps will be as follows:

You will be asked at the end of your triage appointment whether you are happy to give details of someone who knows you well, preferably from birth. If you have provided these details, we will complete an interview with them about your development or about your current behaviour.

When you reach the top of the waiting list, you will complete a comprehensive assessment with two experienced clinicians from our team. You will meet one clinician at a time. The assessment will focus on your childhood and your current situation and you will be asked to complete some tasks that help us to assess your thinking style. You can ask questions and share any information that you think is important.

Case discussions will take place about you between clinicians in the BASS team. These discussions, and all the information you have provided, will inform the diagnostic decision.

Once the assessment is complete there will be one of three outcomes: 

  • You will be given a diagnosis of Autism Spectrum Disorder
  • You will not be given a diagnosis of Autism Spectrum Disorder
  • In rare cases, we do not have enough information to make a decision. In this case you will not be given a diagnosis or we will try to gather more information if available.

Whatever the outcome of your assessment, the clinician will discuss next steps and recommendations with you. A summary of your assessment, outcome and recommendations will be detailed in a report which will be posted to you after your appointment. 

After diagnosis

After an individual receives a diagnosis of Autism Spectrum Disorder, they are invited to attend a six week post-diagnostic support group and weekly advice service. You will be then eligible to receive support from one of the autism advice services.


BASS is based at the Petherton Resource Centre in Bristol.

Telephone: 01275 796 249

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