Can Ulcerative Colitis not appear in the rectum?

I believe UC must involve the rectum as it is continual inflammation, as opposed to say crohns or crohns-colitis. On the other hand, if one is already under treatment and say is just treating the rectum yet the inflammation proximally extends up towards the sigmoid then I would assume the rectal inflammation would disappear but the untreated sigmoid/left sided inflammation would still be present.

If you are treating with rectal meds, it is possible for the rectum to be healed and to have inflammation in other areas. Are you using any enemas or suppositories?

I started out as retum-sigmoid up to 30 cm. Now I'm down to 15 cm just in the rectum.  It appears the disease starts in he rectum the grows upward through the colon. When it heal is retract downwards to the rectum.  The only problem is it leave ou rectum having the longest exposure to UC.

I would have though the disease would fade away eveningly in all areas, but that shows how simpled minded I am!

In my experience, yes. I was diagnosed with moderate left side colitis in 2009. I started Lialda and was pretty much ok for the next 1.5 years. about six months ago I started having a flare. I was on the maximum amount of Lialda per day and started Rowasa nightly. After three months of that, I had a colonoscopy which showed that the sigmoid area still had moderate inflammation but the upper part of the colon and rectum looked ok. I think the oral meds are taking care of the upper part of the colon and the Rowasa healed the rectum, but for some reason, both are having a hard time getting the sigmoid healed.