There is no direct medical test for the diagnosis of Autism Spectrum Disorder (ASD). The diagnostic process typically involves developmental observations of children and behavioral screening methods. These methods include tools such as the Childhood Autism Rating Scale (CARS) and the Modified Checklist for Autism in Toddlers (M-CHAT). CARS assesses a child's behaviors in areas such as social interaction, communication skills, body use, and adaptation to changes. M-CHAT, on the other hand, consists of a standard questionnaire used specifically to screen for signs of autism in young children aged 18 months and older.