2027 ICD-10-CM Diagnosis Code A50.31Late congenital syphilitic interstitial keratitis
ICD-10-CM Codes›A00–B99›A50-A64›A50
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Not Chronic
A50.31 is a billable ICD-10-CM diagnosis code for late congenital syphilitic interstitial keratitis. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 124 through 125. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 79 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Cornea and external disease, Perinatal infections, and Sexually transmitted infections (excluding HIV and hepatitis).
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Bilateral interstitial keratitis of eyes
- Bilateral keratitis of eyes caused by bacteria
- Interstitial keratitis due to congenital syphilis
- Interstitial keratitis due to late congenital syphilis
- Interstitial keratitis of bilateral eyes due to congenital syphilis
- Interstitial keratitis of left eye due to congenital syphilis
- Interstitial keratitis of right eye due to congenital syphilis
- Keratitis due to syphilis
- Keratitis of left eye caused by bacteria
- Keratitis of right eye caused by bacteria
- Syphilitic interstitial keratitis
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to A50.31: its own notes plus those printed at A50.3, block A50-A64, and Chapter 1. A note printed at a category, block or chapter applies to every code under it.
Includes
Further defines, or gives examples of, the content of the category.
- diseases generally recognized as communicable or transmissible
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- human immunodeficiency virus [HIV] disease (B20)
- 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)
Use Additional Code
Add a second code, after this one, to fully describe the condition.
- code to identify resistance to antimicrobial drugs (Z16.-)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name A50.31, its category, or a range that includes it.
Applicable To 1
These notes mention A50.31.
- O98.1 Syphilis complicating pregnancy, childbirth and the puerperium
Excludes2 4
These codes carry an Excludes2 note naming A50.31: its condition is not part of those codes, and both may be reported when the patient has both.
- Chapter 7 (H00-H59) Diseases of the eye and adnexasyphilis related eye disorders (A50.01, A50.3-, A51.43, A52.71) names A50.3-, which includes this code
- Block P35-P39 Infections specific to the perinatal periodcongenital syphilis (A50.-) names A50.-, which includes this code
- P37 Other congenital infectious and parasitic diseasescongenital syphilis (A50.-) names A50.-, which includes this code
- Block A65-A69 Other spirochetal diseases
Code First 1
These codes say to code first a condition named in the note, and A50.31 is one of the conditions named.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Syphilis, Congenital
syphilis acquired in utero and manifested by any of several characteristic tooth (hutchinson's teeth) or bone malformations and by active mucocutaneous syphilis at birth or shortly thereafter. ocular and neurologic changes may also occur.
Patient EducationClinical
Corneal Disorders
Your cornea is the outermost layer of your eye. It is clear and shaped like a dome. The cornea helps to shield the rest of the eye from germs, dust, and other harmful matter. It also helps your eye to focus. If you wear contact lenses, they float on top of your corneas.
Read the full article at MedlinePlus
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Convert A50.31 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About A50.31Overview
What is the ICD-10 code for late congenital syphilitic interstitial keratitis?
The ICD-10-CM code for late congenital syphilitic interstitial keratitis is A50.31 (sometimes written as A5031). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is A50.31 (Late congenital syphilitic oculopathy) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report late congenital syphilitic interstitial keratitis on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does A50.31 group to?
When late congenital syphilitic interstitial keratitis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 125, 124, with relative weights from 0.7699 to 1.2470 depending on complications. Higher weights mean higher Medicare reimbursement.
Is A50.31 a CC or MCC?
CMS lists A50.31 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 79 closely related codes in its exclusion list.
Can A50.31 be reported with A50.53?
Not as a rule. The Excludes1 note at A50.3, which applies to A50.31, lists "Hutchinson's triad (A50.53)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
