Many billing programs will automatically default to include the letters corresponding to the diagnosis in block 21. If you have 4 (or more) diagnosis in block 24e it will often simply default to ABCD. Having this protocol as a default should not lead to any problems for acupuncture claims. However in the instance that a provider has need to point a specific service to specific diagnosis this default would have to be edited. For instance acupuncture is being performed to the neck and back pain which corresponds to diagnosis A and B but there is also massage being done for muscle spasm of a region not related to the neck or back. The line of billing with massage could be pointed to C to correspond to the specific diagnosis where massage is being done.
This pointing is not as critical for acupuncture billing as there are generally no codes that must be reported to a separate region from the primary, acupuncture service. This need is common for chiropractors and physical therapist billing but not acupuncture. Therefore a default to ABCD (or any combination of letters simply not more than 4) would not lead to any denials.
The instruction manual for the 1500 describes use of 24E in this manner:
In 24E, enter the diagnosis code reference letter (pointer) as shown in Item Number 21 to relate the date of service and the procedures performed to the primary diagnosis. When multiple
services are performed, the primary reference letter for each service should be listed first, other applicable services should follow. The reference letter(s) should be letters A through L or multiple letters as applicable. Each letter must be entered separately. Do not enter A-E or similar but 4 separate letters. Enter letters left justified in the field. Do not use commas between the letters. There may be a maximum of 4 letters listed in 24E any additional are simply not reported in this section.