Autism and related disorders do not have a medical or laboratory test for confirmation. In addition, the extent of severity of symptoms makes it even more difficult to diagnose it. Nevertheless, paediatricians now diagnose a lot more children with relative ease due to knowledge about the obvious symptoms of autism.

The most common symptoms of autism include delayed speech and impairment of social interaction. Many children show signs such as avoiding eye contact or physical contact of any form with their parents as infants. Otherwise, the symptoms manifest themselves clearly prior to 3 years of age. It is important that the doctor diagnoses the child for presence of autism early on, during the regular appointments. This type of medical evaluation should be conducted by a specialist, by carrying on a physical examination and review of medical history. The practitioner should have in-depth knowledge about related disorders as well, to suggest a well-defined diagnostic path based on findings. A child with language delay should have a hearing test, to estimate whether person has appropriate hearing ability even at low volumes and high frequencies. A neurological examination is also done, and if it suggests any form of brain abrasion, a CT scan or MRI is conducted.