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O23 vs O99.820

O23 (Infections of genitourinary tract in pregnancy) compared with O99.820 (Streptococcus B carrier state complicating pregnancy), from the official CMS tabular data.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources

Summary

These codes can be reported together when both conditions are documented, because O23 lists O99.820 under Excludes2, which marks them as distinct conditions.

Official rule
What is different?

The conditions named and billing status.O23 is “Infections of genitourinary tract in pregnancy”; O99.820 is “Streptococcus B carrier state complicating pregnancy”. O23 is a non-billable header; O99.820 is billable.

Registry fact

Can these codes be reported together?

Yes, when both are documented.O23 lists O99.820 under Excludes2: “maternal diseases classifiable elsewhere but complicating pregnancy, labor and delivery, and the puerperium (O98-O99)”. Excludes2 marks distinct conditions that may both be reported when both are documented.

Official ruleGuide: Excludes1 vs Excludes2

Is there an Excludes1 relationship?

None.Neither entry carries an Excludes1 note that names the other code. O99.820 carries 1 Excludes1 note covering other codes; the side-by-side table quotes them.

Official rule

Is there an Excludes2 relationship?

Yes.O23’s tabular entry: “maternal diseases classifiable elsewhere but complicating pregnancy, labor and delivery, and the puerperium (O98-O99)”. The note covers O99.820.

Official ruleGuide: Excludes1 vs Excludes2

Is one more specific?

Not comparable.The codes sit in different categories; specificity is only comparable within one category.

Is one a parent or header code?

One is a header.O23 is a non-billable header, but O99.820 is not one of its subdivisions.

Registry fact

Are there sequencing instructions?

None.Neither entry carries a Code First or Use Additional Code note that names the other.

Official rule

Are there other coding relationships?

None found.No laterality, encounter-phase, Table of Neoplasms, Table of Drugs and Chemicals, or history-versus-active-disease relationship links these codes.

MedCoder-derived

Official rule: a tabular instructional note or a section of the ICD-10-CM Official Guidelines, quoted as published. Registry fact: the codes’ own published attributes (titles, billable status, position in the hierarchy, code set). MedCoder-derived: a reading MedCoder computes from those facts; it is not itself a rule. How to read the labels

Can these codes be reported together?

Informational

Excludes2 relationship

O23
Infections of genitourinary tract in pregnancy
↔
O99.820
Streptococcus B carrier state complicating pregnancy

What we found

Yes, when both are documented.O23 carries an Excludes2 note covering O99.820: “maternal diseases classifiable elsewhere but complicating pregnancy, labor and delivery, and the puerperium (O98-O99)”

Excludes2 marks distinct conditions — both may be reported when both are documented.

What to review

Report both only when the documentation supports both conditions; otherwise report the one documented.

Guide: Excludes1 vs Excludes2Check these on a claim

Why it matters

An Excludes2 note means the excluded condition is not part of the code above it, but a patient can have both. Report both when both are documented.

Source / rule

CMS ICD-10-CM tabular instructional notes

Official guidance behind these answers

  • Section I.A.12.b — Excludes2 · applies to: Excludes2

    A type 2 Excludes note represents “Not included here.” An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.

    ICD-10-CM Official Guidelines FY2027

Quoted from the ICD-10-CM Official Guidelines for Coding and Reporting in effect for the release shown. The tabular notes above are the code-level instruction; these sections are the convention that says how such a note is applied. Source document (CMS PDF) · Release and checksum

Side by side

Similar descriptions do not make codes interchangeable. The documentation and the official instructions decide which code applies.

Official descriptionDiffers
O23

Infections of genitourinary tract in pregnancy

O99.820

Streptococcus B carrier state complicating pregnancy

StatusDiffers
O23
Non-billable header

A header is not reported on a claim; a code beneath it is.

Report instead: O23.00, O23.01, O23.02, O23.03, O23.10

O99.820
Billable
Excludes1Differs
O23

None at this code

O99.820
  • Carrier of streptococcus group B (GBS) in a nonpregnant woman (Z22.330)
Excludes2Differs
O23
  • gonococcal infections complicating pregnancy, childbirth and the puerperium (O98.2)
  • infections with a predominantly sexual mode of transmission NOS complicating pregnancy, childbirth and the puerperium (O98.3)
  • syphilis complicating pregnancy, childbirth and the puerperium (O98.1)
  • tuberculosis of genitourinary system complicating pregnancy, childbirth and the puerperium (O98.0)
  • venereal disease NOS complicating pregnancy, childbirth and the puerperium (O98.3)
  • maternal care related to the fetus and amniotic cavity and possible delivery problems (O30-O48)
  • maternal diseases classifiable elsewhere but complicating pregnancy, labor and delivery, and the puerperium (O98-O99)
O99.820
  • genitourinary infections in pregnancy (O23.-)
  • infection of genitourinary tract following delivery (O86.1-O86.4)
  • malignant neoplasm complicating pregnancy, childbirth and the puerperium (O9A.1-)
  • maternal care for known or suspected abnormality of maternal pelvic organs (O34.-)
  • postpartum acute kidney failure (O90.49)
  • traumatic injuries in pregnancy (O9A.2-)
  • when the reason for maternal care is that the condition is known or suspected to have affected the fetus (O35-O36)
Use additional codeDiffers
O23
  • code to identify organism (B95.-, B96.-)
O99.820
  • code to identify condition
  • code to identify specific condition
CategoryDiffers
O23

Is itself a category

O99.820

O99 Other maternal diseases classifiable elsewhere but complicating pregnancy, childbirth and the puerperium

ChapterSame for both

O00-O9A — Pregnancy, Childbirth and the Puerperium (O00-O9A)

IncludesDiffers
O23

None at this code

O99.820
  • conditions which complicate the pregnant state, are aggravated by the pregnancy or are a main reason for obstetric care

No Code first, Code also and 7th character note at either code.

Notes are the code’s own tabular entry, quoted as published. A note that names the other code is the one the verdict above rests on. In a row that differs, notes every code shares are dimmed.

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Derived from the official CMS ICD-10-CM tabular data (FY2027). A coding-rule comparison, not billing advice: payer-specific edits and medical-necessity policy are outside its scope. All data sources