SRS-2 Form

Today I received an Srs-2 form in the post from the educational psycholgist. It says on the form its a diagnostic tool to diagnose  traits of autism. However, my son has not been diagnosed yet. He is seeing the educational psycholgist to get 1-1 assistance in school. 

I assumed only health professionals such as a pediatrician could only diagnose autism

I'm wondering could someone tell me why this needs to be completed, considering they can't provide help for a child who has autism until the health professionals give a full diagnosis of it.