As far as I understand, the sport clubs and/or countries has their medical tests for the competitors in international competitions like Olympic games. However these "regional" exams are not standard world wide (as far as I know) and thus can be biased (also the exam can be biased from lot of other reasons too). I can imagine both:
club/regional/country medical exam can hide conditions that makes the game unsafe for an athlete (if the athlete has a great chance to win)
regional medical exam can fake conditions to gain some advantage (for example there is a lot of talk about asthma pandemic amongst the athletes)
My question - do the particular competitions (for example Olympics) have their own medical comitee and exam every competing athlete to make sure that some "standard" measure was applied to all? Can athletes hide serious problems? Can they fake special conditions to gain advantage?