I'm a patient whos had ulcerative colitis narly 4 years im going for surgery, when my colon is removed and looked at could it show up crohns?

Yes. It is always possible. Blood test may help to differentiate the two as does the endoscopic and histologic findings on your colonoscopy.
Crohns. This is not uncommon, you should continue to be monitored for recurrence of crohns in the remaining colon (if any) and small intestine should be evaluated.

Related Questions

On average, how long before low grade dysplasia of the colon becomes cancer for patients with ulcerative colitis 9 years.

Dyplasia. That is a great question for your gastroenterologist or surgeon. Who is taking care of you? It is impossible to say for sure. You deserve to have the advice of a physician who knows you and the specifics about your condition. . Read more...
UC monitoring. This should be monitored by screening for changes. . Read more...

I'm 29 going for ulcerative colitis surgery removing the whole colon and then having pouch surgery. Later in life what's the chances of geting pergnant.

Pretty good. In younger age group with pouch, getting pregnant is pretty good , long term results are also good with vaginal delivery or by c section. Speak to your doctor(s) , may be at a slightly high risk pregnancy for recurrence of disease. ( not very significant risk ) and need team of experts to carry through good luck. Read more...