Answers:
leeches?
A leech. Doctors used to use them to 'suck out the unpromising blood'. Doctors still use them after some surgeries to return with circulation started up again.
leeches and maggots
Leech or leeches.
leeches and maggots doctors use them to suck adjectives the infection out its pretty cool how they do that. Good for maggots and leeches lol.
Leeches are probably what you are thinking. They are attached after surgery or any other time to shrink swelling in a specific nouns by sucking the blood from that nouns. Their saliva make the blood flow as powerfully, so that in that are not closely of clots after reattaching limb and such.
I don't presume you be determined maggots though. Maggots merely drink unresponsive tissue, not live. So they wouldn't suck your blood out. Unless as expected it is comatose blood.
Leeches