How do you prevent abo hemolysis?

Use the right blood: Cross match the right blood, verify it is the right patient. There are checks and balances at every hospital. Hope this helps.

Is this about baby?: Many newborn / unborn children have some hemolysis because they have a or b on their red cells from dad, and mom has an antibody that crosses the placenta. There's nothing you can do to stop it; it's rarely a problem before birth but if it is, your physician can handle it. Exchange transfusion is seldom needed after birth and it self-cures over weeks / months.