No, a catheter is not always necessary. It depends on where the tumor is located and how deep the biopsy needs to go. Also, males often need a catheter more often than females. The answer is "it all depends." Your urologist is being honest with you. He will not know until the procedure is over.
Diagnosis 2-08 Small papillary TCC; CIS
BCG; BCG maintenance
Vice-President, American Bladder Cancer Society