All medical files are sent to a Regional Medical Office.
When you do an up front medical exam (only spouse, common law and conjugal partner category can do that) at the approved panel physician in your area ( see
http://www.cic.gc.ca/pp-md/pp-list.aspx for more info), the results are sent to the CIC Health Branch and not the VO.
In my case, I did the medical 1 month before sending the application ( 15 Oct) and 9 days later (24 Oct) I received a letter from the CIC Health Branch to go back to the doctor for further tests (they gave me 90 days to comply). I didn't even have a client number, my medical file couldn't be matched to an application because my application was still at home. So what they did, was to assign me a temporary UCI number just for the process of the medical. The medical exam is in a way separated from this, as in the fact that it is being processed on its own and the decision is entered in a data base which the VO can access. The VO does not make decisions on your medical file, only the CIC doctors at the Health Branch. The letter I received was sent by the High Commission of Canada in UK, Health Branch, which is the general office if you don't have a VO yet (like in my case, cause my application wasn't filed).
I went to see the doctor where I previously completed the medical exam, the doctor accessed my file electronically (it's called an eMedical) and she could read there what further tests CIC wanted. She did the tests (I had to pay for them) and the results were filed in my electronic medical file. Never heard from them since. In the meantime, I filed my application where I included the proof of my medical exam (which I got the first time I went to see the doctor) and now I guess CIC will match my file to the medical exam once they start processing it.
This is the letter:
Dear..............
This refers to your application for permanent residence/temporary residence in Canada.
Further medical information is required before a decision can be reached. Details have been sent to your eMedical file regarding the medical information required. Please return to see the Panel Physician who performed your immigration medical examination or to another eMedical enabled Panel Physician. The Panel Physician will arrange for the additional medical tests to be carried out and will forward the results directly to this office.
You have 90 days from the date of this letter to comply with this request.
Please quote your IME number on all correspondence with this office.
Sincerely,
Health Branch
Citizenship and Immigration Canada
High Commission of Canada
Visa Section
London