From the Guide 3999 - Sponsorship of a spouse, common-law partner, conjugal partner or dependent child living outside Canada
http://www.cic.gc.ca/english/information/applications/guides/3999Etoc.asp
<Medical requirements>
Medical instructions
You must undergo an upfront medical examination by contacting a Panel Physician.
Note: When medical results are submitted up-front, routine cases benefit from faster processing since we do not have to request them at a later date. If you choose to have an upfront medical exam, you must submit proof that you completed the medical examination with your application. Failure to do so may result in processing delays.
This guide confused me. But, I think it's better to have medical exams before applying for PR.
http://www.cic.gc.ca/english/information/applications/guides/3999Etoc.asp
<Medical requirements>
Medical instructions
You must undergo an upfront medical examination by contacting a Panel Physician.
Note: When medical results are submitted up-front, routine cases benefit from faster processing since we do not have to request them at a later date. If you choose to have an upfront medical exam, you must submit proof that you completed the medical examination with your application. Failure to do so may result in processing delays.
This guide confused me. But, I think it's better to have medical exams before applying for PR.