Oh I see.
This would be a better article for your old doc then.
In the original description of regional ileitis, Crohn et al1 stated in the clinical features of the new disease entity, “there are none of the perianal fistulae, condylomas or perirectal abscesses that characterize the complications of true colitis, for in this disease the rectum and colon are never involved.” A few years later, Penner and Crohn2 published an article with three case reports of patients with perianal fistulae in regional ileitis and concluded “we were struck by the frequent occurrence of fistula-in-ano as narrated by the patient in discussing past gastrointestinal disorders.”and:
The incidence of perianal manifestations increase the more distal the involvement of the gastrointestinal tract. In a study by Hellers et al,6 perianal fistulae occurred in 12% of patients with ileal disease, 15% with ileocolonic disease, 41% with colonic disease that spares the rectum, and 92% of patients with rectal and colonic Crohn's disease./www.ncbi.nlm.nih.gov/pmc/articles/PMC2780223/Crohn's also - if it spreads - tends to move downwards, unlike UC which does the exact opposite (i.e. start in the rectum and move upwards). So if your Crohn's began in the terminal ileum and first part of the colon, it's certainly possible it could have moved down to the rectum. That's pretty much what happened to me.
I'm worried I'm gonna get perianal disease next :-/