Answer: In most cases, CPT will list the primary or "parent" codes for a particular add-on-code. For instance, if you look at the descriptor for +44128 (Enterectomy, resection of small intestine for congenital atresia, single resection and anastomosis of proximal segment of intestine; each additional resection and anastomsis [list separately in addition to code for primary procedure]) you will note a reference explaining "Use 44128 in conjunction with 44126, 44127."
Unfortunately, CPT provides no such guidance for +44015 (Tube or needle catheter jejunostomy for enteral alimentation, intraoperative, any method [list separately in addition to primary procedure]), essentially allowing individual payers to determine which primary codes are appropriate. A survey of local Medicare carriers provides a partial list of codes with which you may report 44015, including 43620-43622, 44120-44125, 44139, 44140-44147, 44150-44156, 44160, 47120-47125, 47130, 48140-48160 and 74355. To be certain, however, you should contact your carrier for a list of acceptable codes.
Remember that the "add-on" concept applies only to add-on procedures/services performed by the same practitioner. The codes describe additional intraservice work associated with the primary procedure, and therefore you may not report them as a stand-alone service. Modifier -51 (Multiple procedures) is not necessary with any designated add-on code. In addition to payment for the primary service/procedure, the insurer should reimburse for any add-on codes at 100 percent of their value.