Dug out the rule book:
RULE 4 SECTION 9 - BLOOD RULE
A game participant or umpire who is bleeding or who has blood on their uniform shall be prohibited from participating further in the game until appropriate treatment can be administered. If medical care or treatment is administered in a reasonable length of time, the individual will not have to leave the game. The length of time that is considered reasonable is left to the umpire's judgement. Uniform rule violations will not be enforced if a uniform change is required. The umpire shall: A) Stop the game and immediately call a coach, trainer or other authorized person to the injured player and allow treatment. B) Apply the rules of the game regarding substitution, short handed rule and re-entry if necessary.