Probably just to double-check the growth hasn't penetrated outside the bowel or how much bowel is affected. Supposedly, that can happen. Doesn't mean they're checking for cancer. Some things just need surgery to be removed properly.  Not saying yours does, but yeah that's why they're probably checking.

Thanks so much ProfBaw for your reply. It's just been so upsetting thinking I've had the all clear for 2 weeks to now get this. The removal process was really complex- I had to have 7 bowel clips put on and the ESR machine or whatever it's called malfunctioned. So in my head I'm telling myself it the scan might be just to check that nothing was left because it was so traumatic - but then the more I look on this forum a request for a CT scan seems to point to something more sinister. As you can tell my heads been in a bit of a spin so I really appreciate your response. 
betty xxx

Here's a previous thread (just looked it up for you).  There's a guy in the thread called "rich". From what you've said, yours was complex and in keeping with what he said, they need to make sure they have it all if it was a large and complex one.

www.cancerresearchuk.org/.../is-ct-scan-and-mri-straight-after-colonoscopy-normal

Hopefully that puts your mind at ease that they do this with more complex ones.

Thanks so much ProfBaw - weirdly when I click on the link it comes up with this same discussion post we are on? Would you mind kindly resending so I can take a look?

thank you so much 

B x

I've edited the post.  Let me know if that works.  No idea how i managed to link your thread.

Thanks so much that worked - really appreciate it. 
betty x