CT scan,now endoscope procedure today why would this be the case if a diagnosis had already been made from the

Ct scan.My mum has been in and out of hospital 3 times in as many months due to intense pain in her stomach.She had a ct scan was diagnosed with pouches in her intestines and an ulcer in her bowel.She was pumped full of antibiotics and after a week allowed home without a follow up scan to see if the antibiotics were working to remove the ulcer.
Less than 2 weeks later she was back after something burst inside her and the pus/fluid released through her bladder.My mum thinks it was the ulcer bursting and the hospital tends to agree.So 2 questions.....1)If this is the case,surely she must have a perforation between her bowel and bladder or how else did the pus come through her bladder?
And 2)Why would she now be having an endescope(camera inserted into anus)if they already know she has an ulcer in her bowel...oh and she has already had a rectal exam which was normal?

My mum had the procedure,camera wasn't able to fully enter all of the bowel(there was a blockage)she now has to have a barium meal.Could this be the ulcer blocking the camera and if so why did the doctor not know what the blockage was even though it has a camera on the end of the tube?

These 2 tests are to obtain further information...like is there any further disease in the affected area...what caused the problem...is there a reason why the original problem began and how is the best way to treat the problem.
A Ct scan shows the whole lower or higher area to also find out why the problem occurred in the first place.
Good luck to mom.
P.S. The scope could also take biopsies etc to see how the antibiotics worked.

endoscope goes farther into the bowel than a rectal exam. The rectal exam only goes in as far as the finger can, the endoscope can travel the intestines.

well man i thnk it should be an internal fistula and thats the reason for the bladder leak..the CT scan is to stage the disease suppose its an malignant condition and if its not malignant it can be helpful to find the extent of the disease..the endoscopy is also to find out the prognosis of the ulcer and may be find the efficacy of the treatment.