Always a tough call - but if you DID NOT SEE the hit - wait. If you saw the hit - but the arrow did not go clean through - wait.

If you saw the arrow disappear behind the shoulder - GO GET IT. First though spend some time looking for the arrow - the arrow will tell alot.

When you do go after the deer - LISTEN very carefully for a deer getting up and/or bolting while trailing. Of course if you jump the deer - back uot and come back in the morning.

Good luck - post us back with a picture!