T33.70XS
Superficial frostbite of unspecified knee and lower leg, sequela
T33.70XS (also written T3370XS) is a billable ICD-10-CM diagnosis code for superficial frostbite of unspecified knee and lower leg, sequela. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 111 codes in category T33 (Superficial frostbite). Its 7th character, S, means sequela. Its coding notes include a Use additional code instruction and 4 Excludes2 entries.
7th character
Category T33 requires a 7th character. T33.70 has only 5 characters, so a placeholder X fills the 6th position.
Guidelines tip
From the FY2027 Official Guidelines. ICD10Ref adds no rules of its own.
The 7th character depends on whether the patient is in active treatment, not on who sees the patient. An aftercare Z code is not used for injury aftercare.
Use additional code
Add the listed code as a secondary code, if known.
Also from chapter/block level (1 note)
- code to identify any retained foreign body, if applicable (Z18.-)
Excludes2
Not included here. Both codes may be reported if the patient has both conditions.
- superficial frostbite of ankle and foot (T33.8-)
Also from chapter/block level (3 notes)
- birth trauma (P10-P15)
- obstetric trauma (O70-O71)
Includes
Further defines or gives examples of the content of the category.
- frostbite with partial thickness skin loss
Notes
Also from chapter/block level (2 notes)
- Use secondary code(s) from Chapter 20, External causes of morbidity, to indicate cause of injury. Codes within the T section that include the external cause do not require an additional external cause code
- The chapter uses the S-section for coding different types of injuries related to single body regions and the T-section to cover injuries to unspecified body regions as well as poisoning and certain other consequences of external causes.