The general rule is that you can't miss more than 8 training days of BCT. If you miss more than that, then normally you are released from BCT and sent home. The good news is that if, whatever the reason you missed more than 8 days, is temporary or repairable, then you are automatically given a slot for next year. Of course in that time you will have medical reviews done on you to ensure that the reason for being released has been corrected/healed.
And I say "Normally" because the academy has final say on the matter. They can waiver the 8 days and allow more. Such as with those this past year with swine flu. Or maybe it's an injury that while not at 100%, they feel that it is minor enough to allow you to skip certain portions of training and allow you to stay. mike....