What is a false positive in autism screening and why is follow-up essential?

• A. A screen misses an existing ASD.
• B. A screen suggests ASD and is always confirmed by diagnosis.
• C. A screen that suggests ASD but diagnostic evaluation does not confirm ASD; follow-up interviews reduce false positives and prevent unnecessary referrals.
• D. A screen causes immediate referral.

Answer: (C)

Screening tools are designed to flag potential autism cases, but a false positive happens when the screen suggests ASD even though a formal diagnostic evaluation does not confirm it. That’s why follow-up is essential: the initial screen is a first step, not a diagnosis. A thorough diagnostic evaluation brings in multiple pieces of information—developmental history, careful observation of social-communication skills, language, and behavior, and input from caregivers—often using standardized assessments and clinical judgment. This process helps distinguish ASD from other conditions that can look similar, like language delays or other developmental differences, and it confirms whether diagnostic criteria are truly met. Following up also prevents unnecessary referrals and the associated stress for families when the screen was overly cautious or flagged non-ASD behaviors. In short, screening casts a wide net, and follow-up hones in on who genuinely needs autism-specific intervention.