Cervical conization (CPT codes 57520 (Cold Knife) and 57522 (Loop Excision)) refers to an excision of a cone-shaped sample of tissue from the mucous membrane of the cervix. Conization may be used either for diagnostic purposes as part of a biopsy, or for therapeutic purposes to remove pre-cancerous cells. Cervical conization (CPT codes 57520 (Cold Knife) and 57522 (Loop Excision)) refers to an excision of a cone-shaped sample of tissue from the mucous membrane of the cervix. Conization may be used either for diagnostic purposes as part of a biopsy, or for therapeutic purposes to remove pre-cancerous cells.