I probably have sacroiliitis. The rheumatologist hasn't mentioned AS, but anytime I search for SI, I get results that it's the first stage of AS. Can you have SI without having AS? I know my rheum drew blood for the HLA-B27 antigen and if that's positive, it sounds like it's AS. I also had my rheumatoid factor checked, as well as a pelvic/hip MRI (x-rays are normal, but that's not unusual, from what I've read). I should get results this week, but just wondering if anyone has any insight.