Early diagnosis and treatment are the keys to improving the quality of life for kids with ASD. Unfortunately, there is no medical test for autism.
Autism is diagnosed based on a professionals observation of how your child talks and acts in comparison to other children of the same age. The diagnosis is typically done by play-based testing with the child in combination with asking the parents questions regarding behavior and history.
If you have concerns that your child is not developing normally, it is important to bring your concerns to your primary care physician. Check out early signs and symptoms here.