Deep Vein Thrombosis (DVT) Support Group
Deep-vein thrombosis, also known as deep-venous thrombosis or DVT, is the formation of a blood clot ("thrombus") in a deep vein. It can be caused by something preventing blood from circulating or clotting normally. Join the support group if you are coping with DVT and find others who are going through the same challenges.
With a lot of injuries, like with a puncture from a needle to take blood, you'll wind up with a superficial clot to stop the area from bleeding. That's kind of necessary. OF course, there's a big difference between a superficial clot and a DVT. Docs don't worry about superficial clots (because it means your body is working correctly), but DVTs are a different issue.
I couldn't say if your blood coagubility levels change as a whole when you're injured. With absolutely no scientific knowledge to back me up, I think your blood is able to clot if it needs to to try to repair damage when it needs to. I expect there are dozens of little bumps and dings that your body deals with every day that don't result in DVTs.
I can think of one situation where the coaguability levels change a lot and that would be during late pregnancy and childbirth. Obviously, there will be a higher survival rate among women who don't bleed out during childbirth, so I think the blood clots more easily during that time as a life-saving device. Definitely helpful if you're one of our ancestors giving birth in a sod shanty on the prairie.
As for other times that the body increases your coagubility levels, I couldn't say. Might be an interesting question for your hematologist.
So I think part of the equation is if you're prone to clotting already and the other part is risk factors that would potentially cause clots. In an otherwise healthy person, it seems the risk would be low to develop blood clots from a venus puncture. But I have no medical data to back that up, and I agree with Toss, it may be a question to throw at your doctor to get his take.