Create your own blood trickle- put some red food coloring in water, mix a touch of black or dark blue, corn syrup and thickener (here's a bunch of other recipes:
http://www.wikihow.com/Make-Fake-Blood ), fill a baloon (white or green, matte finish) and stab that. You can get some pretty decent elements with any HD camera/DSLR.
Tudor "Ted" Jelescu
Senior VFX Artist