Progesterone injections

I have done now 4 cycles of Ivf. Each one successful in terms of getting pregnant. Injections are something I'm all too familiar with. Today for the first time ever they when I started my injection and pulled the plunger out that there was blood in the syringe. First time ever. We're talking about roughly 29 weeks I have given myself progesterone injections now. I was surprised at first and then confused. What do you do with it? 

I squirt it out the bed I could and continued in with the rest of my injection.