What your dad's doc is proposing is a TURB (transurethral resection of the bladder.) This is done under general anesthetic...often as an outpatient procedure. With your dad's age it is likely that he may get to stay overnight. The urologist will remove as much of the growths as possible as well as some of the adjoining tissue and send these to the pathology lab for analysis. ONLY AFTER THE RESULTS FROM THE PATH LAB ARE BACK WILL HE KNOW EXACTLY WHAT THE DIAGNOSIS IS. With all his experience he will have a pretty good idea, but it will take the path report to determine if it is high or low grade or if it has spread into the adjacent tissue. These results will help define what, if any, treatment your father should receive. Your dad may have some residual discomfort for a few days, particularly if it is necessary for him to have a catheter.
This is a relatively minor procedure, as medical stuff goes, but your dad's age is a factor. He should do well.
Sara Anne