Hi there, I have A/v TOS bilaterally, and do not have cervical ribs. You do not have to present with a c-rib or a blood clot to be diagnosed with it. I have had a successful surgery on each side (left side first, it was urgent) and have had an excellent recovery. My surgery was in AZ- far away from PA, I know. I was just "unlucky" like your son- just wasn't born with enough room in there basically. If you go for surgery for your son, do you research on the surgeon, and the pre and post op treatment. If you're at all able, see if you're able to go to Boston to see Dr. Donahue as Mass general. If that isn't possible, be sure to ask the surgeon how often he/she has done this, how comfortable they are... ect. As far as further testing, a Doppler ultrasound (which is what it sounds like your son has had) is a great real time tool. He could have an arteriogram done as well, though its a bit more invasive. Getting a CT scan with contrast was very helpful in my case, very similar to getting a venogram done, but they are looking at there the dye goes/doesn't go once it reached the arteries. Positional is important! Must have those arms up and sticking up over the head to get an accurate test. If there's nothing wrong with your son in this test, then the dye should go in and out of his arteries with arms up with little issue. If there is a compression, that dye will stall, maybe even completely (it did for me- zero blood flow!) and that is a very good indication of surgery needed. Good luck and keep us posted!