Tā de shǒu bèi jīqì juǎn zhù, shāngkǒu xuèròumóhu.
His hand was caught in the machine and the wound was a gruesome mess.
Tips
register
Graphic and visceral — reserve for genuinely gory contexts (accidents, combat, injuries). Not for metaphorical 'messy' situations. 糊 is neutral tone (hu) per CC-CEDICT.
usage
Not in the Xinhua chengyu dictionary but well-established in CC-CEDICT and modern usage. A relatively recent fixed phrase rather than a classical idiom.