9.2 Autism Spectrum & Developmental Delay

Autism spectrum disorder and developmental delay sit in the same high-volume clinical category as ADHD, but the primary-care job is different. For ADHD you often diagnose and treat in the office. For autism you recognize, screen, refer, start services immediately, and manage medical comorbidities. Waiting for a perfect diagnostic letter is the high-yield miss.

Autism is two domains, not "late talking"

DSM-5-TR autism spectrum disorder requires:

1. Persistent deficits in social communication and social interaction — reduced joint attention, limited back-and-forth, poor sharing of affect, reduced eye contact or gesture, difficulty with peer relationships appropriate to developmental level.
2. Restricted, repetitive patterns of behavior, interests, or sensory difference — stereotyped movements, insistence on sameness, intense circumscribed interests, hyper- or hyporeactivity to sound, texture, or pain.

Both domains are required. A chatty child with no friends and intense lining-up of toys can meet criteria. A late talker with excellent pointing, pretend play, and social smiling often does not. Symptoms begin in the early developmental period, though they may not fully declare until social demand exceeds capacity (preschool, kindergarten).

M-CHAT-R/F, then simultaneous action

AAP Bright Futures surveillance is every well visit. Standardized autism-specific screening with the Modified Checklist for Autism in Toddlers, Revised, with Follow-Up (M-CHAT-R/F) is the usual tool at 18 and 24 months (the validated window is roughly 16–30 months). The follow-up interview reduces false positives from a parent yes/no sheet.

A positive screen is not a diagnosis. It is a trigger for two actions the same week, not a sequential queue:

• Refer for comprehensive diagnostic evaluation (developmental-behavioral pediatrics, child psychology/psychiatry, or a multidisciplinary autism clinic).
• Refer to Early Intervention (IDEA Part C) if younger than 3, or to the school district (IDEA Part B) if 3 or older.

Do not delay Early Intervention while waiting for a specialist. AAP is explicit: start services based on clinical concern. Diagnostic wait lists are months long in many regions. Part C eligibility can rest on delay or on an established-condition path; parents can also self-refer. Your letter should say "concern for autism spectrum / social-communication delay — please evaluate and begin services," not "hold therapy until Dr. X confirms."

Clinic vignette. An 18-month-old fails M-CHAT-R, and the follow-up interview stays positive: no pointing, no response to name, hand-flapping when excited. The next developmental-pediatric opening is in five months. You still refer to Part C now, arrange audiology, and keep the diagnostic referral. The wrong answer is "let's wait and see at the 2-year visit."

Global delay vs isolated speech delay vs autism

These three are not synonyms. PNCB can write a toddler who is "late to talk" and expect you to pick the frame.

Regression (lost words, lost social skills) is a red flag for autism and for neurologic or genetic disease — accelerate referral; do not soothe with "boys talk later."

Hearing test for language delay — always

Every child with language delay needs objective hearing assessment, even if the caregiver says the child startles to the dog or "hears the tablet." Informal startle is not an audiogram. Middle-ear fluid, congenital hearing loss, and auditory neuropathy all stall language. Treat cerumen and chronic effusion, but do not let "maybe it's just fluid" cancel the formal test. Autism evaluation does not replace audiology; audiology does not replace autism evaluation when social communication is impaired.

Part C and therapies: start on concern

IDEA Part C covers Early Intervention from birth until the third birthday. Referral is a primary-care skill: send, follow that the family connected, and plan the Part C to Part B transition before age 3. After the third birthday, school-based services (IEP) and outpatient therapies run in parallel.

Evidence-based autism interventions include applied behavior analysis (ABA) and developmental, speech-language, and occupational therapies (including play-based/naturalistic developmental behavioral models). Intensity is individualized. You do not have to name a brand-name protocol on every item. You do have to refer for therapy based on clinical concern and not hold services hostage to a completed genetic panel or a university-clinic diagnosis.

Vaccines do not cause autism. If a caregiver asks, answer directly and still start EI — counseling is not a reason to freeze the referral.

Genetic testing: coordinate, do not delay care

For autism and for unexplained GDD, first-tier genetic evaluations commonly discussed in AAP/ACMG language are chromosomal microarray and Fragile X testing (Fragile X in boys always; consider in girls with ASD/GDD as well). Additional tests (PTEN with macrocephaly, MECP2 in a girl with regression) are specialist-driven.

The CPNP-PC's job on this exam is recognition and routing, not personally resulting every gene panel in the well-child room. Some medical-home practices order first-tier tests; many refer to genetics or developmental pediatrics. Either way:

• Do not delay EI, speech, or ABA while labs pend.
• Do not tell families that a normal microarray "rules out" autism — autism is a clinical diagnosis.
• Recurrence-risk and family-planning questions belong with genetics once the child is connected.

Clinic vignette. A 26-month-old has GDD (motor and language) and poor joint attention. You refer to Part C and audiology today. You discuss that microarray and Fragile X are usual first-tier tests and place a genetics or developmental referral to complete that work. You do not postpone therapy until the microarray posts.

Medical comorbidities the primary-care NP still owns

Identification is not the end of the medical home.

Wandering, pica, and elopement are safety counseling (locks, ID, water safety), not optional extras.

Exam traps

1. Wait-and-see after a failed M-CHAT-R/F.
2. Holding Part C until a specialist confirms autism.
3. Skipping hearing because the toddler "hears the TV."
4. Calling isolated speech delay autism — or calling autism "just speech delay" when joint attention is absent.
5. Believing the PC NP must personally order every genetic panel before any therapy, or that genetics replaces clinical diagnosis.
6. Ignoring sleep, constipation, seizures, and feeding once the autism label exists.

Screen, refer, start EI on concern, test hearing, coordinate genetics, treat the body. That is 9.2.