Most surgeries won’t even be big or bad enough to need blood, and most of the time everyone’s on top of things and the blood bank has a “type and screen” on surgical patients long before they make the trip down the OR hallway. But sometimes, especially when it’s a patient who’s been in the hospital for a few days already, they can end up on the OR table, needing blood, and the blood bank has to tell the surgeon they can’t have it immediately because the old specimen is expired. Trust me, that’s no fun for anybody. Least of all the poor patient.
And when I say a specimen is expired, I don’t mean it’s gone moldy or anything. But your body is not static. Every single unit of blood you get challenges your immune system, and increases the chances that you’ll form an antibody against a foreign protein on donor cells. So we ask for a new specimen to be drawn every 3 days, so we can catch any changes and detect antibodies before we give you incompatible blood. Blood that was fine for you three days ago might not be fine for you now, if your immune system made an antibody against something in it.
Antibodies aren’t necessarily a big deal. In the majority of cases, we can still find compatible blood pretty easily, but the problem is time. A normal type and screen, where we confirm blood type and screen for antibodies to red cell proteins, takes a little over 30 minutes. Once we have that done, adding on units of blood takes 5 minutes. It’s really that fast – once the OR calls to ask for blood, we have it ready before the tech shows up at the door to pick it up. But in a situation with a new antibody, even the simplest work-up will take over an hour, and most of the time it’s a little more involved. We have to test the plasma against a panel of known donor cells to figure out what specific antibody is present, then we have to pull units from our supply and type them for the corresponding antigen – only those that are negative for that antigen will be safe for the patient with that antibody. That can take up to a half hour. If there’s more than one antibody present, the typing takes longer, and sometimes we need to ask the Red Cross reference lab to check their rare donor stash to find us some blood and send it to us, which takes hours. Once we have the right kind of units, the crossmatch itself takes 20 minutes.
Imagine trying to do that, under pressure, knowing the patient needs blood now. When we have advance notice and get the specimen early enough, we always set up extra blood on antibody patients so it’s there quickly if it’s needed. In a desperate situation the doctor can opt for uncrossmatched units, which can be risky, but the doctor weighs the risks of not transfusing vs the risk of the patient having a reaction, and makes that call. Obviously, we all hate the idea of uncrossmatched blood in principle, and we try to only give patients the safest blood possible after crossmatching it. So we like to avoid unnecessary surprises, like when a patient gets all the way to the operating room for a major surgery without anyone checking on the blood bank.
Be your own advocate, and ask. Worst case, you’ll irritate a nurse or doctor. Best case, you’ll be sure you won’t get in trouble mid-surgery because the blood bank needs a couple of hours to find safe blood for you under pressure.