Is ICD-10-CM code A74 billable?

No, A74 (Other diseases caused by chlamydiae) is a non-billable ICD-10-CM code. It must be coded to a more specific subcategory before it can be used for reimbursement.

What chapter does ICD-10-CM code A74 belong to?

A74 belongs to Chapter 1 of the ICD-10-CM tabular list: A00–B99 (Certain Infectious and Parasitic Diseases).

A74Not billable, use a more specific code below

Other diseases caused by chlamydiae

In Other diseases caused by chlamydiae (A70-A74), chapter 1: Certain Infectious and Parasitic Diseases

4 billable codes under A74: none are a CC or MCC; none map to an HCC.

Instructional notes

Excludes1: not coded here, use a different code

neonatal chlamydial conjunctivitis (P39.1)
neonatal chlamydial pneumonia (P23.1)
Reiter's disease (M02.3-)
sexually transmitted chlamydial diseases (A55-A56)

Excludes2: not included here, code separately if applicable

chlamydial pneumonia (J16.0)

Also applies, from Other diseases caused by chlamydiae (A70-A74)

These notes sit on A70-A74 and apply to every code under it, including A74.

Excludes1: not coded here, use a different code

sexually transmitted chlamydial diseases (A55-A56)

Official coding guidelines

From the ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027 (CMS and NCHS). Links open the PDF at the right page.

Rules for coding infections and parasitic diseases, including HIV, organism and drug resistance codes, sepsis and septic shock, MRSA, Zika, and COVID-19.

Human Immunodeficiency Virus (HIV) Infections (page 19)
Infectious agents as the cause of diseases classified to other chapters (page 22)
Infections resistant to antibiotics (page 22)
Sepsis, Severe Sepsis, and Septic Shock (page 23)
Methicillin Resistant Staphylococcus aureus (MRSA) Conditions (page 27)
Zika virus infections (page 28)
Coronavirus infections (page 28)

Read Section I.C.1 (page 19)

All codes under A74

A74 can't be used on a claim. Pick a billable code below; grey headings group them.

A74 MS-DRGs

As the principal diagnosis, the billable codes under A74 group to MS-DRG 865, 866, 124, or 125 (v44.0). Which one applies depends on procedures performed, secondary diagnoses (CC/MCC), and the patient's age and discharge status.

DRG 865 Viral Illness with MCC (3 of 4 codes)
DRG 866 Viral Illness without MCC (3 of 4 codes)
DRG 124 Other Disorders of the Eye with MCC or Thrombolytic Agent (1 of 4 codes)
DRG 125 Other Disorders of the Eye without MCC (1 of 4 codes)

Other codes that refer to A74

Notes on these codes point to A74.

A56 Excludes2: conditions classified to A74.-

About the condition

Plain-language background from MedlinePlus (National Library of Medicine), not coding guidance.

Bacterial Infections

Bacteria are tiny organisms (living things) that have only one cell. Under a microscope, they look like balls, rods, or spirals. They can be found almost everywhere on Earth. There are lots of bacteria in and on your body. In fact, your body has about 10 times more bacteria cells than human cells.

Code history

Valid since FY2016, when ICD-10-CM took effect on October 1, 2015. No changes since.