S27.309A — Unspecified injury of lung, unspecified, initial encounter
Is S27.309A billable?
Yes, but S27.309A will trip a Medicare edit. S27.309A is a valid, billable ICD-10-CM code for encounters from October 1, 2026 through September 30, 2027. However, CMS lists S27.309A under Medicare Code Editor edit 20, “Unspecified code” — meaning a code specifying laterality (right, left or bilateral) exists in the same family. On an inpatient claim this triggers the edit, because CMS holds that there are very limited circumstances in which laterality cannot be documented.
S27.309A at a glance
| Code | S27.309A |
|---|---|
| Description | Unspecified injury of lung, unspecified, initial encounter |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
| 7th character "A" | initial encounter |
What does the 7th character "A" mean in S27.309A?
In S27.309A, the 7th character A means initial encounter. The 7th character is required for S27.309A to be a valid, complete code.
Same condition, different episode of care — switch the 7th character:
What Medicare edits apply to S27.309A?
The Medicare Code Editor screens inpatient claims before they are grouped. These edits name S27.309A directly.
A code specifying laterality (right, left or bilateral) exists in the same family. CMS holds that there are very limited circumstances in which laterality cannot be documented.
Which MS-DRGs does S27.309A group to?
S27.309A sits in MDC 04 and helps define the logic of 2 MS-DRGs (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.
- 205Other Respiratory System Diagnoses with MCCmedical
- 206Other Respiratory System Diagnoses without MCCmedical
As a secondary diagnosis, S27.309A is a complication or comorbidity (CC), which can move a stay into a higher-paying DRG.
How is S27.309A listed in the Alphabetic Index?
The Alphabetic Index lists these routes under S27.309, the nearest indexed parent of S27.309A. Use them to find the family, then select the specific code.
- Injury › intrathoracic › lung
Use additional code — inherited from Chapter 19
Report an additional code alongside S27.309A to fully describe the condition. S27.309A is sequenced first.
- code to identify any retained foreign body, if applicable (Z18.-)
Excludes2 — not included here — inherited from Chapter 19
The conditions below are not part of S27.309A, but a patient may have both at the same time. When documentation supports it, S27.309A and the excluded code may both be reported.
Excludes2 — not included here — inherited from S20-S29
The conditions below are not part of S27.309A, but a patient may have both at the same time. When documentation supports it, S27.309A and the excluded code may both be reported.
- burns and corrosions (T20-T32)
- effects of foreign body in bronchus (T17.5)
- effects of foreign body in esophagus (T18.1)
- effects of foreign body in lung (T17.8)
- effects of foreign body in trachea (T17.4)
- frostbite (T33-T34)
- injuries of axilla
- injuries of clavicle
- injuries of scapular region
- injuries of shoulder
- insect bite or sting, venomous (T63.4)
Excludes2 — not included here — inherited from S27
The conditions below are not part of S27.309A, but a patient may have both at the same time. When documentation supports it, S27.309A and the excluded code may both be reported.
Code also — inherited from S27
Two codes may be needed to describe the condition fully. Whether S27.309A is sequenced first depends on the reason for the encounter.
- any associated open wound of thorax (S21.-)
How long has S27.309A existed?
S27.309A has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.