T66-T78 — Other and unspecified effects of external causes
ICD-10-CM codes T66-T78 cover other and unspecified effects of external causes, within injury, poisoning and certain other consequences of external causes. The block holds 660 codes across 11 categories, of which 456 are billable and 204 are header codes that cannot be submitted on a claim. 660 of them (100%) require a 7th character.
Code also
Both codes may be needed to describe the encounter fully. Sequencing depends on the reason for the visit.
- , if applicable, place of occurrence, such as:
- highway rest stop (Y92.523)
- school (private) (public) (state) as the place of occurrence of the external cause (Y92.21-)
- service areas as the place of occurrence of the external cause (Y92.52-)
- single-family non-institutional (private) house as the place of occurrence of the external cause (Y92.01-)
- transport vehicle as the place of occurrence of the external cause (Y92.81-)
The 7th character in T66-T78
A code in this block is not complete without its 7th character, and a missing one is a rejected claim rather than a denied one: the clearinghouse never passes it on. 660 of the 660 codes here take one.
- A
- initial encounter
- D
- subsequent encounter
- S
- sequela
Risk adjustment in T66-T78
0 codes in this block map to a CMS-HCC, which means the diagnosis carries a risk-adjustment payment when it is documented and coded. Under-coding here is money left on the table; over-coding here is what audits are for.
- HCC 155 Major Depression, Moderate or Severe, without Psychosis
What else to watch in T66-T78
- 16 codes are laterality-specific. They come in left and right pairs, and the pair is mutually exclusive on a single site: coding both without a bilateral code is a contradiction a scrubber should catch before the payer does.
- 402 codes are named in Medicare coverage policies. An LCD or NCD lists them as supporting medical necessity, or explicitly as not supporting it. Which applies depends on the MAC for your state.
Categories in T66-T78
- T66Radiation sickness, unspecified
- T67Effects of heat and light
- T68Hypothermia
- T69Other effects of reduced temperature
- T70Effects of air pressure and water pressure
- T71Asphyxiation
- T73Effects of other deprivation
- T74Adult and child abuse, neglect and other maltreatment, confirmed
- T75Other and unspecified effects of other external causes
- T76Adult and child abuse, neglect and other maltreatment, suspected
- T78Adverse effects, not elsewhere classified