Fazio went to the United States to hone his skills in all aspects of intestinal surgery, firstly at the Lahey Clinic Hospital in Boston, then, in 1973, to learn alongside surgeon Dr Rupert Turnbull at the Cleveland Clinic.
Specialising in colon and rectal surgery, Fazio's clinical interests were Crohn's disease and ulcerative colitis; colorectal cancer; and pelvic floor reservoir procedures, created inside the body of patients who had intestines removed, to collect the body's waste.