My GI did this too to rule out CD. He couldn't understand why I could not gain remission so by taking a CT scan they can check for illness in the small intestine and rule out or in CD. I wouldn't worry about it, your doctor is being proactive and thorough.
dx proctitis in 1987
dx UC in 1991, was stable until 1998
1998 started prednisone, asacol, pentasa, nortriptylene, ativan, 6MP, rowasa enemas and suppositories, hydrocortisone enemas, tried the SCD diet, being a vegetarian, omega 3s, flax, pranic healing, yoga, acupuncture, probiotics
2000 lost all my B-12 stores and became anemic
2001 opted for j-pouch surgery- now living life med-free