A56.4 Chlamydial infection of pharynx

The ICD-10-CM code for Chlamydial infection of pharynx is A56.4 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

1: Certain infectious and parasitic diseases (A00-B99)

Section

A50-A64: Infections with a predominantly sexual mode of transmission (A50-A64)

Category A56

13 codes (10 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to A56.4:

• Pharyngitis (acute) (catarrhal)(gangrenous) (infective) (malignant) (membranous) (phlegmonous) (pseudomembranous) (simple) (subacute) (suppurative) (ulcerative) (viral) › chlamydial
• Chlamydia, chlamydial › pharyngitis
• Infection, infected, infective (opportunistic) › Chlamydia, chlamydial › pharynx
• Disease, diseased › venereal › chlamydial NEC › pharynx

U.S. Hospital Utilization

A56.4 appeared in too few sampled U.S. inpatient stays in 2023 to report a national estimate (AHRQ suppresses counts of 10 or fewer) — a rare inpatient diagnosis.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Official Coding Guidelines

HIV Infections (TOC entry)

a. Human Immunodeficiency Virus (HIV) Infections .............................................................. 19

Infectious agents causing diseases in other chapters (TOC)

b. Infectious agents as the cause of diseases classified to other chapters ................................. 22

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)