A50.40 — Late congenital neurosyphilis, unspecified
Is A50.40 billable?
Yes, but A50.40 is an unspecified code. A50.40 is a valid, billable ICD-10-CM code for encounters from October 1, 2026 through September 30, 2027. However, A50.40 is an unspecified or catch-all code. Payers apply additional scrutiny to unspecified codes and many deny them when the medical record supports a more specific option, so check the documentation before selecting A50.40 — the more specific alternatives are listed below.
A50.40 at a glance
| Code | A50.40 |
|---|---|
| Description | Late congenital neurosyphilis, unspecified |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
Which MS-DRGs does A50.40 group to?
A50.40 sits in MDC 01 and helps define the logic of 3 MS-DRGs (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.
- 097Non-Bacterial Infection of Nervous System Except Viral Meningitis with MCCmedical
- 098Non-Bacterial Infection of Nervous System Except Viral Meningitis with CCmedical
- 099Non-Bacterial Infection of Nervous System Except Viral Meningitis without CC/MCCmedical
As a secondary diagnosis, A50.40 is a complication or comorbidity (CC), which can move a stay into a higher-paying DRG.
How is A50.40 listed in the Alphabetic Index?
These are the routes through the Alphabetic Index that lead to A50.40. They show the wording a clinician may have documented, which often differs from the Tabular description.
- Neurosyphilis › congenital (arrested) (early) (gumma) (late) (latent) (recurrent) (relapse)
- Neurosyphilis › juvenile (arrested) (early) (gumma) (late) (latent) (recurrent) (relapse)
- Syphilis, syphilitic › central nervous system › congenital (acquired)
- Syphilis, syphilitic › central nervous system › juvenile (acquired)
Inclusion terms
Alternative wording in documentation that is classified to A50.40.
- Juvenile neurosyphilis NOS
Excludes1 — never code together — inherited from A50-A64
The conditions below can never be reported together with A50.40 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
Excludes1 — never code together — inherited from A50.4
The conditions below can never be reported together with A50.40 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
- Hutchinson's triad (A50.53)
Use additional code — inherited from Chapter 1
Report an additional code alongside A50.40 to fully describe the condition. A50.40 is sequenced first.
- code to identify resistance to antimicrobial drugs (Z16.-)
Use additional code — inherited from A50.4
Report an additional code alongside A50.40 to fully describe the condition. A50.40 is sequenced first.
- code to identify any associated mental disorder
Excludes2 — not included here — inherited from Chapter 1
The conditions below are not part of A50.40, but a patient may have both at the same time. When documentation supports it, A50.40 and the excluded code may both be reported.
- carrier or suspected carrier of infectious disease (Z22.-)
- certain localized infections - see body system-related chapters
- infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)
- infectious and parasitic diseases specific to the perinatal period (P35-P39)
- influenza and other acute respiratory infections (J00-J22)
Excludes2 — not included here — inherited from A50-A64
The conditions below are not part of A50.40, but a patient may have both at the same time. When documentation supports it, A50.40 and the excluded code may both be reported.
- human immunodeficiency virus [HIV] disease (B20)
How long has A50.40 existed?
A50.40 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.