ANSWER: PDD or Pervasive Developmental Disorder is actually a
bit of a misnomer. Many doctors who would not like to commit to
giving a diagnosis of Autism will tell the parents that their child
has PDD or PDD NOS. ANSWER: PDD-NOS stands for Pervasive
Developmental Disorder-Not Otherwise Specified. PDD is another name
for autism spectrum disorder (ASD). Some doctors use PDD when they
mean PDD-NOS. Some doctors use PDD as what it is - a set of
disorders. PDD is not a diagnosis; it is a description of a
category of developmental disorders. PDD-NOS is a diagnosis. It
describes a condition that has the characteristics of a pervasive
developmental disorder, but does not fit the criteria for one of
the other PDDs.
Sometimes, doctors will use the diagnosis of PDD-NOS when it is
apparent that the child has a pervasive developmental disorder, but
the exact one cannot yet be determined - perhaps because the child
is too young to identify certain symptoms, or the disorder is not
severe enough to differentiate from the others yet, or comorbid
conditions are making it difficult to differentiate among the
disorders. Some doctors prefer not to give a diagnosis of autism
until they feel absolutely sure that it is autism, so they diagnose
the child with PDD-NOS until they are certain.