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ICD-10-CM 2027 diagnosis code

A56Other sexually transmitted chlamydial diseases

Not billable — use a more specific code

A56 is a header code, so it can't be reported by itself. Choose one of the 6 more specific codes beneath it.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About A56

A56 is the ICD-10-CM diagnosis code for other sexually transmitted chlamydial diseases. It belongs to block A50-A64 (infections with a predominantly sexual mode of transmission) and chapter 1 (certain infectious and parasitic diseases). It is a header code, so it can't be reported by itself; one of its 6 subcodes must be used instead.

To report this condition, pick the subcode that matches the documentation: A56.0 (tract), A56.1 (organs), A56.2 (unspecified), A56.3 (rectum), A56.4 (pharynx) and A56.8 (sites).

Don't report A56 together with the conditions in its Excludes1 note: neonatal chlamydial conjunctivitis (P39.1) and neonatal chlamydial pneumonia (P23.1).

The conditions in its Excludes2 note aren't part of A56, but may be coded alongside it if the patient has both: chlamydial lymphogranuloma (A55) and conditions classified to A74.-.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Specific codes under A56

Coding notes

IncludesFurther defines the content of the category
  • sexually transmitted diseases due to Chlamydia
  • trachomatis
Excludes1Not coded here — never report together with this code
  • neonatal chlamydial conjunctivitis (P39.1)
  • neonatal chlamydial pneumonia (P23.1)
Excludes2Not included here — may be reported together if both conditions exist
  • chlamydial lymphogranuloma (A55)
  • conditions classified to A74.-

Notes that apply from higher levels

Instructions written at a parent level also apply to A56.

Broader instructions also apply from A50-A64 Infections with a predominantly sexual mode of transmission and Chapter 1: Certain infectious and parasitic diseases.

Codes whose notes reference A56

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about A56

Is A56 billable?

No. A56 is a header code. Report one of its more specific subcodes instead.