Absolutely need a colonoscopy. Best of luck!
Oh, the colonoscopy procedure is not as difficult as one might imagine, your husband will be well-sedated, he is kept covered up really well, a nurse will be right there to reassure him and increase his meds if he feels any discomfort along the way. The main thing is, I think it's important for the doc to be able to visualize the parts of his intestine that HAVE been shown to not only be irregular, but also now the latest CT scan shows the descending colon is collapsed. This may create even worse digestive issues.
So, you're all scheduled, and actually the "prep," where you only drink this dye stuff and not eat anything the day before, is the hardest part of the whole thing! And the colonoscopy will allow the doc to really understand what has happened, and thus come up with a way to really get his intestinal tract straight, and also sometimes that procedure reveals lots of stuff a scan will not, so his best chance for complete resolution of his problems is the colonoscopy. But if the doc can agree to hold off and treat your husband as best he can from the results of the scan, and then your husband gets worlds better, sure, could be you wouldn't need the colonoscopy. But I'd keep that appointment as long as I could, if I were you. It may really be an important test for your husband, and will definitely allow for better results in treating him, especially when some of that colon has collapsed! THAT worries me.