Seeking an autism assessment can be a daunting and overwhelming process for individuals and families. Many face long waitlists, inconsistent assessment procedures, varying costs, and a wide range of practitioner qualifications. Some clinics offer online-only autism assessments, while others may require screeners, in-person evaluations, or a combination of both. With so many variables, it’s no wonder families feel unsure about where to start.

It can be tempting to choose the fastest route—a short waitlist and a minimal test battery—to receive a quick diagnosis. However, for autism assessments in British Columbia, standardized tools like the ADI-R (Autism Diagnostic Interview-Revised) and the ADOS (Autism Diagnostic Observation Schedule) are required. Reports based solely on virtual screenings or questionnaires often do not meet provincial diagnostic standards and may be rejected by healthcare providers, schools, or funding agencies.

To help individuals, parents, and caregivers better understand this process, I’ve created a comprehensive autism assessment guide that outlines key considerations and common pitfalls. Below, I share the top three reasons why a quality autism diagnostic assessment takes time—and why that time matters.

1. Autism Screeners Are Just the Starting Point—Not the Whole Picture

By the time a family reaches out to me, they’ve often already completed several autism screeners—sometimes through their family doctor or online tools. These screeners may show elevated scores that suggest autism, but screeners are not designed to provide a formal diagnosis.

For example, the M-CHAT (Modified Checklist for Autism in Toddlers) has strong predictive value, identifying around 83% of children who later receive an autism diagnosis. However, this still means 17% of children flagged by the screener may not actually meet diagnostic criteria. Additionally, many symptoms that raise red flags for autism—such as difficulty maintaining conversations—can also occur with other conditions like ADHD, anxiety, or language disorders.

Screeners are designed to flag concerns, not confirm them. A proper autism diagnosis requires a more in-depth, comprehensive evaluation.

2. A High-Quality Autism Assessment Must Consider Differential Diagnoses

One of the most important elements of a proper autism assessment is evaluating whether symptoms could be better explained by another diagnosis. This is called differential diagnosis, and it’s a crucial step in avoiding misdiagnosis.

For example, a common referral concern is difficulty with social interaction or conversation. While this could suggest autism, it could also point to language delays, attention difficulties, or emotional regulation issues. In some cases, a child may have co-occurring conditions that influence their behavior in different ways.

As a clinician, my assessment process includes tools to evaluate cognitive abilities, adaptive functioning, and emotional health, alongside autism-specific tools like the ADOS and ADI-R. This holistic approach aligns with best practice guidelines and enables me to offer personalized recommendations that meets your child’s needs. 

3. Developmental History Is Essential for an Accurate Autism Diagnosis

A thorough developmental history is one of the most important—and often overlooked—components of an autism assessment. According to the DSM-5-TR, symptoms of autism must be present in early childhood, even if they only become noticeable later when social demands increase.

That’s why it’s critical to gather information about a child’s early developmental milestones, typically through a caregiver interview. For adults seeking a diagnosis, this step can be more difficult, but it’s still essential. When caregivers aren’t available, alternative sources like early report cards, home videos, or previous evaluations can help fill in the gaps.

In my practice, I always complete a detailed intake using the ADI-R, a gold-standard tool for collecting developmental history. When possible, I also review academic records, prior reports, and video footage to ensure a complete picture. This step helps distinguish autism from other conditions and is non-negotiable for a valid diagnosis.

Final Thoughts

While it may be tempting to opt for a faster or cheaper route, a high-quality autism assessment requires time, depth, and expertise. Quick or incomplete assessments often lead to confusion, misdiagnosis, or invalid reports that don’t meet regional standards—especially in British Columbia.

If you’re navigating this process for yourself or a loved one, know that a thorough and thoughtful approach will yield not only a clearer diagnostic outcome but also more meaningful supports and services. I’ve created a free autism assessment guide to support families through these decisions.