What follows is not intended to start an argument, although I know there are strong views about the subject. But I wanted to present another possibility about "blood" (that I've seen the poster "Terry" make also).
The decrees set out in Acts are listed below. Acts 15:19-21 represents the decree arrived at in the meeting in Acts 15. And verses 28-29 represent what was in the letter sent out to the Gentile Christians.
Acts 21:25 has a repreat of what is in the letter in 15:28-29. The order of decrees is the same as in 15:28-29, so I left 21:25 out.
(Acts 15:19-21)
Hence my decision is not to trouble those from the nations who are turning to God, but to write them to:
(1) abstain from things polluted by idols and
(2) [abstain] from fornication and
(3) [abstain] from what is strangled and
(4) [abstain] from blood.
For from ancient times Moses has had in city after city those who preach him, because he is read aloud in the synagogues on every sabbath.”
(Acts 15:28, 29) (This is the same order as in Acts 21:25)
For the holy spirit and we ourselves have favored adding no further burden to YOU, except these necessary things,
(1) to keep abstaining from things sacrificed to idols and
(2) [keep abstaining] from blood and
(3) [keep abstaining] from things strangled and
(4) [keep abstaining] from fornication.
If YOU carefully keep yourselves from these things, YOU will prosper. Good health to YOU!"
The actual decision differs from the outgoing letter with regard to blood matters.
In 15:19-21 it is 'abstain from things strangled' and 'abstain from blood.'
In 15:28-29 it is 'abstain from blood' and 'abstain from things strangled.'
This argues that the one (blood) is not dependant on the other (things strangled). In other words, it can't mean (paraphrasing):
'Abstain from unbled meats (because you would be eating blood) and abstain from other types of eating blood.'
If it did mean this, it wouldn't make sense to reverse the order in 15:28-29. The reversing of the order would mean that "[abstain] from blood" stands on its own. It is a seperate item from "[abstain] from things strangled."
Now consider how Luke uses the term "blood" in both Luke and Acts:
Luke
8:43, 44 Woman with a 'flow of blood'
11:50-1 Shedding of blood of prophets
13:1 Pilate shedding blood
22:20 Jesus' reference to his own (soon to be) shed blood
22:44 Sweat becoming like drops of blood
Acts
1:19 Field of blood (burial plot bought with Judas' blood money)
2:19 Blood - in quotation of Joel apocalyptic prophecy
2:20 Moon becoming blood - turning red from smoke (same Joel prophecy)
5:28 killing of Jesus
18:6 blood guiltiness
20:26 blood guiltiness
20:28 Jesus shed blood
22:20 Stephen's shed blood
If we take out the two quasi medical uses (8:43, 44 and 22:44), all the other references to "blood" have some relation to the shedding of blood or possible blood guiltiness, as in becoming responsible for someone's death.
I would argue (and I'm sure I'll be challenged on it), but I would argue that Luke's use of "blood" in Acts 15:19-21, 15:28-29, and 21:25 is in some way related to this aspect of "blood," not to eating or consuming it.
One might argue that 'shedding of blood' should have been a 'no-brainer' for the Gentile Christians. My counter argument would be that outright fornication should have been also.
I would further argue that the decree must have been in relation to particular aspects of "fornication" and "blood" that were sensitive to Jews, but to Gentiles may have been considered 'grey' areas (for example, treatment of household slaves and wives - or compare 1 Cor 5:1). After all, the idea of the decree was, not so much helping Gentiles establish a relationship with God (which the account assumes they already had), but rather, to help them and their Jewish brothers get along better.
It might also be worth considering that Luke is writng some years after the actual decree and its associated letter went out, and after the problems involved may have settled down. Luke may actually be giving a brief sysnopsis of the letter for the sake of his readers, rather than the whole letter in its entirety.
The upshot of all this would be that "[abstain] from blood" would have nothing to do with any modern (or even ancient) medical uses of blood, or the actual consuming of blood.
[Edited to add: I had to copy this out of the editor and then back in to overcome formatting problems. I don't know if it involves this editor of Chrome or what.]