Menopause Question

I am 41 and have had heavy periods lasting approx 7-8 days for years coupled with a posterior fibroid. My gyn suggests a DNC. In the meantime, my periods have gone from exactly 28 days to this one coming after only 15 with all the regular flow, etc. In the last 2 months I have also experienced 2 bouts of rectal bleeding, more like mucous with low back bain immediately after. I have seen a colorectal surgeon who suggests (as a precaution only) a colonoscopy. I do not want to go under anesthesia 2 times. Which procedure would most likely give me a diagnosis?