I have never heard of a jpouch (ileoanal anastomosis) being given for IBS. Have you consulted with a CR surgeon?
The answer to your question is yes, it can be done in one step but it's usually the surgeon's perogative how many steps are taken. Prednisone history is one consideration as well as physiology. Often a surgeon doesn't make the decision on number of steps until the patient abdomen is open on the OR table.
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