Labs will test for this but its an added cost.Lets say for a second that every bottle of steroids is sterile!As soon as you put the needle threw the rubber stopper you put unsterile air into the muti dose vile.So now you have an unsterile product,now what,throw it out?I think not.Something is ether sterile or its not sterile..........no inbetween.I take every precaution to insure I keep things clean and to minamize the chance of contamination.I shower before injection,wipe vial top with iso,new needle to draw,new needle to inject,wipe site with iso before injection and then wipe with iso after injection.If your really unsure of the UG labs sterility,put the vial,before you open it,into the micrwave and heat for a couple min.No need to vent top.Watch it very closely.Also remember that the larger the multi dose vial the more chances of geting it contaminated.Stick with 10ml bottles,they are safer.