Knife, stick, rebar, or fragment sticking out of the body
Red flags
In the chest and they cannot breathe: seal around the object as best you can, do not pull it.
Do not
Do not pull it out. It may be plugging a vessel.
Exception only: it blocks the airway and they cannot breathe, or it stops you doing chest compressions on a dead casualty you are trying to revive — and even then, only what you must.
Field aid tool — not a diagnosis, not a medic, not your unit’s official protocol. When a trained medic or doctor is there, follow them.