We went through the same process, it was frustrating, but we finally got it done. Took two mths to get authorization though.
First, get the referal from your Primary Care Physician (PCP) and book an appointment with your doctor at Shady Grove. Book it atleast a mth in advance, so you have time to get the authorization as well.
Then call your insurance and ask to speak to someone regarding authorization. IMP: jot down this person's name, extension, and fax number.
Then call your PCP, and ask them to speak and ask for the same person when submitting requests for authorization. They're gonna ask your PCP a ton of questions, such as cause for referal, etc etc.
Finally, MDIPA will take all this info, and eventually give you an authorization. Then, you want to have this authorization faxed to Shady Grove.
Good luck!