That sucks. I lost the first deer I ever shot after tracking her for 11 hours. I've tracked a few deer over the years and here are some of the things they have taught me about tracking.
Deer never vanish but they are very good at avoiding predators, every time you bump one(when you said you found pools of blood I would assume the deer stopped, maybe even laid down and watched its back trail)you make it more difficult to find. The farther you push a deer the more tricks he can pull out to shake you off of his trail. On a gut shot deer or any deer you have to track more than 100-150 yards you should wait, time is your ally, let him lay down and die. Never track a gut shot deer in the dark unless he has been laying for a few hours (my personal minimum is 4 hours, unless it's raining).
Always stay on blood, if you run out of blood go back to the last drop then look for more blood, its there you just have to find it. I have had blood trails go from big splashes of blood every few feet to a single drop every few yards, but the blood was there I just had to get down close to the ground and look harder.
Animals, especially old deer do have quite a few tricks to avoid being trailed, I've seen or heard of them walking in water, backtracking through their own trail, jumping to the side of the trail, even licking their wounds clean. One thing to look for is blood that has run down a leg, this will leave a bloody footprint pointing in the direction the deer traveled, also blood splatter can tell you direction of movement, these things will be useful in determining if a deer turned around and walked down his backtrail.
You didn't mention if you recovered the arrow or not, if the arrow is still in the deer it should be bleeding as the arrow will keep the wound open, also a broadhead bouncing around in his stomach will do a lot of residual damage.
Don't believe all that crap about deer going down hill or to water, a gut shot deer will often do these things but I've seen a couple go up and down a few hills before expiring. One thing you might do is go to last blood and look around for a place where the deer could watch his back trail while at the same time get the wind to smell anything walking up behind him. If he is there he will probably be in a tangle of the thickest, nastiest bramble he could find or possibly laying right behind it.
Remember a gut shot is always fatal, even if your arrow only went in six inches. I had a gut shot deer go almost a half mile and a single lung hit go just over a half mile, I'm not surprised that your deer didn't pile up in the first couple hundred yards. If you are like me, an average shot who is constantly harassed by murphy(of Murphy's law fame), You need to learn to track. It often helps to have someone along just to boost you confidence and keep you looking, don't invite too many people though, one or two friends at the most, several peaople looking for a deer usually just get in the way of each other. Remember my biggest rule while trailing ALWAYS STAY ON BLOOD. I hope this helps, keep us posted.
