Clopidogrel may cause bleeding, which can be serious and sometimes lead to death.

FORBES: FDA Approves Generic Clopidogrels As Plavix Loses Patent Protection

Sometimes doctors delivered the polymer to the wrong place, causing internal bleeding and kidney damage.

FORBES: Magazine Article

Although surgical techniques can sometimes be learned by practising on cadavers, microsurgery requiring careful control of bleeding needs living animals.

ECONOMIST: Animal rights extremists

Sometimes, here at alt.engadget.com, we're literally on the bleeding edge of technology.

ENGADGET: Alt-week 9.22.12: Quantum Scotch tape, moving walls and scientific beer