Belinda - if AS is allowed to get to a classic stage of "bamboo spine" or sacroiliac joint fusion, then there really isn't any question about the diagnosis if you see the xrays, and you wouldn't need any other information. Your father obviously has enough of those clear and unequivocal (can't be anything else) signs.
However, there can be 10 or 20 or more years of active disease before it gets to that point, and in the earlier stages doctors have to look for a lot more clues (none of which are 100 percent reliable) to make the diagnosis. With women, its often even more difficult because the pattern of disease and rate of fusion can be quite different.
