3 months after bladder cancer surgery the scab has not dissolved. what does this indicate?

Will fall of: If you are asking about scab on the abdominal wall ( due to open surgery/ not through the bladder ) most likely you had small collection under the skin which resolved , keep moist dressings the scab will fall off soon and go to the surgeon for follow up.

Keloid formation: The bad collagen - which forms the scab is the cause for this also called keloid formation. To reset this use methionine supplement 500mg twice daily this will stabilize the normal scar formation and strengthening of scar. The other product that can balance the inflammatory reaction is vitamin E oil, laser therapy, mild steroid therapy.