How Do I Code a Sequela (Late Effect)? Two Codes, the Residual First, and the 7th Character S

Official source

“A sequela is the residual effect (condition produced) after the acute phase of an illness or injury has terminated. There is no time limit on when a sequela code can be used. The residual may be apparent early, such as in cerebral infarction, or it may occur months or years later, such as that due to a previous injury. Examples of sequela include: scar formation resulting from a burn, deviated septum due to a nasal fracture, and infertility due to tubal occlusion from old tuberculosis. Coding of sequela generally requires two codes sequenced in the following order: the condition or nature of the sequela is sequenced first. The sequela code is sequenced second.”

Official source

“An exception to the above guidelines are those instances where the code for the sequela is followed by a manifestation code identified in the Tabular List and title, or the sequela code has been expanded (at the fourth, fifth or sixth character levels) to include the manifestation(s). The code for the acute phase of an illness or injury that led to the sequela is never used with a code for the late effect.”

The “cause” half of the pair takes one of two forms. For injuries, poisonings and the other Chapter 19 categories, it is the original injury code with the 7th character S — Section I.C.19.a: “When using 7th character ‘S’, it is necessary to use both the injury code that precipitated the sequela and the code for the sequela itself. The ‘S’ is added only to the injury code, not the sequela code. The 7th character ‘S’ identifies the injury responsible for the sequela. The specific type of sequela (e.g. scar) is sequenced first, followed by the injury code.” For diseases, it is a dedicated sequela category: I69, Sequelae of cerebrovascular disease; the B90–B94 block, whose section note says these categories “are to be used to indicate conditions in categories A00-B89 as the cause of sequelae, which are themselves classified elsewhere” and which carries a Code First note for “condition resulting from (sequela) the infectious or parasitic disease.”

1. Confirm the acute phase is over and the documented condition is a residual of it. Time does not matter; phase does.
2. Code the residual condition first — the scar (L90.5), the contracture, the deviated septum, the infertility.
3. Add the cause second: an injury → the injury code with 7th character S (S52.501S); an infectious disease → the B90–B94 code (B90.9 for tuberculosis); a stroke → the I69 code.
4. Check for an expanded sequela code. I69.3- lists the residuals in the code itself — I69.351, hemiplegia following cerebral infarction affecting the right dominant side — so the single code carries both halves; a separate hemiplegia code is not added. That is the I.B.10 exception.
5. Never report the acute code (I63.- for the infarction, the A15–A19 code for active tuberculosis, the injury with 7th character A or D) alongside the sequela. History codes are a different question: I69 carries an Excludes1 for Z86.73, history of cerebral infarction without residual deficit — no residual, no sequela code.
6. Burns: a healed burn’s scar takes the burn code with 7th character S (I.C.19.d.7), and a current burn with 7th character A or D may be reported on the same record as the sequela of an old one (I.C.19.d.8).

1. Keloid-free scar of the forearm from a burn two years ago, seen for scar revision.L90.5 → the burn code for the site with 7th character S. Residual first, injury second.
2. Malunion-free residual deformity after a healed right distal radius fracture. The residual condition’s code → S52.501S.
3. Right-dominant hemiplegia documented as following a prior cerebral infarction.I69.351 alone — the sequela code is expanded to include the residual. I63.- is not reported.
4. Bronchiectasis documented as a sequela of old pulmonary tuberculosis. The bronchiectasis code first → B90.9, per the B90–B94 Code First note.

• Coding the acute condition with the sequela — never; the acute phase is over.
• Putting S on the residual’s code — S goes on the injury code only.
• Sequencing the injury-S code first — the residual leads.
• Adding a separate hemiplegia code to I69.35- — the expanded sequela code already carries it.
• A sequela code when no residual exists — that is a history code (Z86.73 for stroke without deficit; Z87.- for healed injuries).
• Treating the time since the injury as decisive — there is no time limit either way.

• A residual condition linked to a prior illness or injury — the pair the two codes describe.
• Whether the acute phase has ended (sequela) or treatment continues (subsequent encounter, 7th character D — the 7th-character guide).
• No residual at all — a history code, not a sequela code.
• For I69: the specific residual, the side, and dominance.