The HI-External Cause of Injury segment indicates "In order to fully describe an injury using ICD-10-CM, it will be necessary to report a series of 3 external cause of injury codes." Does this mean that when this segment is used and an ICD-10 E-code is billed that three E-codes must be billed or the txn must be rejected? Or....is it acceptable to interpret the note to mean that if you want the full description, you will need three to fully describe the injury, however, you aren't required to enforce 3 e-codes be billed?
There are two parts to your question.
1- Must a receiver reject a transaction that does not comply with the governing Technical Report Type 3 (TR3)?
This question is answered in RFI 1512.
2- Is a transaction reporting 1 or 2 external cause of injury codes compliant with the 005010X223A2 Technical Report Type 3 (TR3)?
Three external cause of injury codes are not required in all circumstances since the Industry Usage for data elements HI02 and HI03 is Situational, not Required. The Situational Rules specify that HI02 is only sent when more than one external cause of injury code must be sent and HI03 is only sent when more than two external cause of injury codes must be sent. HI02 and HI03 are not sent otherwise. Therefore, a transaction with 1 or 2 codes does comply with the TR3. The segment note you reference was removed after publication of the version 5010 TR3 in order to avoid confusion.