Wow, you certainly do a lot of research, and that's okay, but try not to worry about the colonoscopy as a procedure very much, it's not that bad. I'll try to provide some input on some of your questions as somebody who has Crohn's Disease and has had quite a few colonoscopies. If you feel you need more information on specifics, you'll need to refer to your doctor about additional specifics on some of the tests you mention as some of your inquiries are more unusual for somebody going through a colonoscopy. Here it goes ...

Your bowel and other rectal symptoms as described are not *necessarily* indicative of active IBD/UC and could be some type of infection going on with you. Usually with IBD/UC you'd be having persistent diarrhea, abdominal cramping, the blood would be more than just a spotting, you might be experiencing unexplained weight loss, etc. BUT it's good to check for it in your case, as IBD can manifest itself differently for each person, often with highly varied symptoms and degrees of those.

1. Medications to discontinue prior to the procedure should be listed on your prep information that is provided to you. But generally you'll have to NOT take any NSAIDs, no blood thinners, and no iron. I think some blood pressure meds and diabetic medications may also be on the list. Your doctor/nurse should be able to address the specific ones you have listed, but they do not ring any bells for me.

2. You will almost certainly have biopsies taken to test for IBD given your family history of UC. This would also include specifically biopsies of polyps that may be found and tested for cancerous cells. Larger polyps may be excised totally to reduce the risk of them becoming malignant in the future. A very large number of polyps would be an indication for concern but don't preoccupy yourself with that idea before the results come back. You may notice some blood in your bowel movements, and/or after passing the gas right after the procedure from biopsies and that's not unusual to be a worry for you. Ask your doctor's office in advance about the test for mast cells to make sure that is done to look for allergic reactions you think might need to be ruled out and to test for abnormalities that could indicate other problems. You may get some push-back on requesting specific tests but it's your body.

3. As a man I cannot really speak to your gynecological questions other to agree with you that it's possible to notice in the colonoscopy that you have a fistula opening in the colon that would have to be traced. Often a CT scan or better an MRI is done to do the trace of the tract of a fistula, but here is some more detailed information on what to think about: https://www.mayoclinic.org/diseases-conditions/rectovaginal-fistula/diagnosis-treatment/drc-20377113.

I am not aware of any liver related issues that can be checked for by colonoscopy.

You have enough going on in your body that it may be necessary to systematically rule out one or more possible maladies that could be on hand with you. The colonoscopy along with biopsies and the mast cell tests sound like a good area to look at what's going on with you. I'm sorry that you don't have the confidence in your GI at the moment and understand why you'd be going through this now given your situation, and if you don't get satisfactory explanations by all means go for a second opinion, especially if you can get referred to Mayo. My mother had gastric distress that was killing her years ago that was not diagnosed until after going to Mayo and found to have a blockage and intestinal looping. After a myriad of tests the specialists were telling her that it was all in her head ... You are your own best advocate for your health. And good luck! 🙂