expression, godan verb (-su)
shed blood
Literal and figurative expression for bleeding or causing bloodshed, often used in dramatic or serious contexts.
彼は戦いで血を流した。
He shed blood in the battle.
これ以上血を流すべきではない。
We should not shed any more blood.
出血 is a medical/formal noun meaning 'bleeding' or 'hemorrhage', while 血を流す is a more vivid, often figurative verb phrase.
Compound of 血 (blood) + を (object marker) + 流す (to let flow). The expression is transparent and follows standard Japanese grammar.