It’s hard to get people to donate blood at all, and O is the rarest type. It probably happens a lot. And if they’re out of something else, O is universal blood so maybe some gets used for a guy with AB-. But people with O can only take O.
To further this, the negative and positive value also matters. Someone with a negative type can only take negative blood, whereas a positive type can accept both.
I wish it were easier to get people to donate. Just this morning I heard a radio advertisement for the blood service that included the line ‘please schedule and attend an appointment’, which seems wild that so many people book a time then don’t show up.
When does a hospital casually not have O- blood
It’s hard to get people to donate blood at all, and O is the rarest type. It probably happens a lot. And if they’re out of something else, O is universal blood so maybe some gets used for a guy with AB-. But people with O can only take O.
To further this, the negative and positive value also matters. Someone with a negative type can only take negative blood, whereas a positive type can accept both.
Here's a little chart:
Source
I wish it were easier to get people to donate. Just this morning I heard a radio advertisement for the blood service that included the line ‘please schedule and attend an appointment’, which seems wild that so many people book a time then don’t show up.