This is something Dolittle said in a previous post. It doesn't address blood in the syringe (yikes) but may address your other question.
"I do have an answer to Bogies question about how they tell if your band is leaking. The easiest way they can tell, is when you have a fill, if the place you go to is any good, the fill doctor or tech will pull all the fuild out of your band to see how much is in there, then compare it to previous records. If there's a big variation, then there's a possiblity something is might be wrong. The next step would be to watch the refill via the fluoroscope and see if the fuild is leaking. All good bandsters should keep track of how much they have in their band. Try to use the same fill clinic and the same doctor, because they will keep records of this too. But sometimes you might end up at another fill clinic, that's when it pays to know your numbers. I personally have never heard of the band leaking, I've heard of badly done fills at shotty clinics where they have missed the port and hit the tube or damaged the port. Also,, some of these so called fill clinics can accidently not pull all the fuild out and then proceed to tell you somethings wrong. Talk about giving someone some anxiety. This is why it's to your best interest to check out fill clinics before you go to them. My best advise is to go back to the OCC for your fills. My opinion is that they still do the best job at filling your band. I live in the Midwest, if I plan it right and watch airline sales, it's almost the same cost to go back to TJ versus going to one of those so called fill clinics. I know its a little inconvenient to go back to TJ,, but I sleep better at night. "