Mri of pelvis report said changes consistent with adenomyosis. is it true adenomyosis will eventually cause heavy bleeding/pain &need for hysterectomy?

Why was the MRI done: Incidental findings like this one are not uncommon. That is why we do not advice doing tests(like MRI) without a clear reason/search for a specific diagnosis causing unexplained pain or swelling. I would advice you to wait to worry about all the consequences of adenomyosis when you/we are not even sure that you have this diagnosis! (worry when you have a real problem, not in anticipation!