Look at the websites or literature for donating blood, here in the UK, such as the National Blood Service. They say they take an amount which is about 470 ml, some sites say 450 ml, or maybe just around 400 ml. But they refer to it, misleadingly, as just under a pint.
So why do UK medical people, e.g. those in the NHS, who should know better, keep saying the phrase "just under a pint", when they should be saying "just under half a litre"?
450 ml or 470 ml are both a lot less than a UK pint.
Alternatively, the UK medical people are convinced that a UK pint is the same as a US pint of 473 ml and have no idea of how things are in this country. I do not trust medical people who have no idea of what a UK pint is, and who try to hide the amount of blood by giving out misinformation.
And if the body holds on average, say 9 pints of blood (according to blood website figures), that is 9 x 0.568 = 5.1 litres.
1 unit of blood = 450 ml, but as a percentage of the total, 5.1 litres, it is only 8.8%. Yet those who are taking the blood say they are taking 12% of the body's total blood volume.
The thing is, if they gave out proper measurements, then the amount taken would be described in a way that shows it is a lot less than what they say, and might encourage more people to donate blood. I would feel uncomfortable giving 12% of my blood, but perhaps more comfortable with giving only 8.8%.
The sooner the health services stop using pints the better, especially the pint that has a wrong definition by them.
They should quote it as just under half a litre, about 9% of an average person's blood. Or maybe even cut down the amount taken, to a round amount, something like 400 ml, or even just 300 ml or 250 ml. But never a pint, nor an amount that they mistakenly describe as a pint even though it is at least 25% less.
