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ICD-10-CM O99.820: Streptococcus B carrier state complicating pregnancy

O99.820 is the billable ICD-10-CM code for streptococcus B carrier state complicating pregnancy, in category O99 (Other maternal diseases classifiable elsewhere but complicating pregnancy, childbirth and the puerperium) of the Other obstetric conditions, not elsewhere classified section. As a principal diagnosis it groups to MS-DRG 817 Other Antepartum Diagnoses with O.R. Procedures with MCC, MS-DRG 818 Other Antepartum Diagnoses with O.R. Procedures with CC, MS-DRG 819 Other Antepartum Diagnoses with O.R. Procedures without CC/MCC (MDC 14 MDC 14: Pregnancy, Childbirth and the Puerperium). 1 LCD billing and coding article lists it as covered.

Compiled from CMS files by the QuickIntell RCM Editorial Team · Data effective · Method: reference methodology · Report a data correction

Data currency: ICD-10-CM code descriptions: FY2027 (effective October 1, 2026); IPPS Table 5 (MS-DRG weights): v44 FY2027 (final rule + CN3) (effective October 1, 2026); ICD-10-CM to HCC mapping: PY2027 initial ICD-10-CM mappings (dates of service 2026) (payment year 2027); Medicare Coverage Database billing and coding articles: MCD release October 8, 2026 (effective October 4, 2026). Next CMS release: FY2028 code files, effective October 1, 2027 for the ICD-10-CM code descriptions; FY2028 final rule (August 2027), effective October 1, 2027; an April 1 interim grouper update when CMS issues one for the IPPS Table 5 (MS-DRG weights); PY2028 advance notice (February 2027) and the PY2027 midyear final mapping (spring 2027) for the ICD-10-CM to HCC mapping; weekly, every Thursday for the Medicare Coverage Database billing and coding articles.

Code
O99.820
billable FY2027 ICD-10-CM code
Category
O99 Other maternal diseases classifiable elsewhere but complicating pregnancy, childbirth and the puerperium
Chapter
15: Pregnancy, childbirth and the puerperium (O00-O9A)
CC/MCC (MS-DRG v44)
Neither
CMS-HCC V28
Not mapped
POA reporting
Required

Tabular list notes for O99.820

The tabular list has no notes on O99.820 itself; the notes below apply from its parent headings.

Inherited from O99 (Other maternal diseases classifiable elsewhere but complicating pregnancy, childbirth and the puerperium)

Includes
  • conditions which complicate the pregnant state, are aggravated by the pregnancy or are a main reason for obstetric care
Excludes2 (not part of this condition, may be coded together)
  • when the reason for maternal care is that the condition is known or suspected to have affected the fetus (O35-O36)
Use additional code
  • code to identify specific condition

Inherited from O99.8 (Other specified diseases and conditions complicating pregnancy, childbirth and the puerperium)

Inclusion terms
  • Conditions in D00-D48, H00-H95, M00-N99, and Q00-Q99
Excludes2 (not part of this condition, may be coded together)
  • 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-)
Use additional code
  • code to identify condition

Inherited from O99.82 (Streptococcus B carrier state complicating pregnancy, childbirth and the puerperium)

Excludes1 (never coded together)
  • Carrier of streptococcus group B (GBS) in a nonpregnant woman (Z22.330)

MS-DRG grouping when O99.820 is the principal diagnosis

MS-DRG v44 groups for O99.820 as principal diagnosis
MDCMS-DRGs
14 MDC 14: Pregnancy, Childbirth and the Puerperium817818819831832833

The final group also depends on procedures, secondary diagnoses and discharge status; the MS-DRG lookup for O99.820 shows the full grouping logic.

CC/MCC status and inpatient edits

O99.820 is neither a CC nor an MCC under MS-DRG v44, so as a secondary diagnosis it does not raise the MS-DRG severity level. Check O99.820 against a principal diagnosis.

  • Present on admission: a POA indicator is required on inpatient claims.
  • Medicare Code Editor: age conflict: maternity diagnosis (age 9 to 64); unacceptable principal diagnosis.

CMS-HCC V28 risk adjustment

O99.820 does not map to a payment HCC in the PY2027 CMS-HCC V28 model, so on its own it does not change a Medicare Advantage risk score.

LCD billing and coding articles that list O99.820

1 current Medicare billing and coding article lists O99.820 among the diagnoses that support medical necessity for the services they cover.

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Frequently asked questions

What does ICD-10-CM O99.820 mean?

O99.820 means streptococcus B carrier state complicating pregnancy. It is one of 25 billable codes under O99, other maternal diseases classifiable elsewhere but complicating pregnancy, childbirth and the puerperium.

What can't be coded with O99.820?

Excludes1 at O99.82: Carrier of streptococcus group B (GBS) in a nonpregnant woman (Z22.330). These are never reported together with O99.820.

Which MS-DRG does O99.820 group to?

As the principal diagnosis, O99.820 groups to MS-DRG 817 Other Antepartum Diagnoses with O.R. Procedures with MCC, MS-DRG 818 Other Antepartum Diagnoses with O.R. Procedures with CC, MS-DRG 819 Other Antepartum Diagnoses with O.R. Procedures without CC/MCC (MDC 14 MDC 14: Pregnancy, Childbirth and the Puerperium) under MS-DRG v44, before procedures and secondary diagnoses are applied.

Sources

Every figure on this page is taken from the CMS publications below, as released by the Centers for Medicare & Medicaid Services. Projection built 2026-10-10. Verify against the primary file before billing or contracting decisions. The reference methodology explains how each figure is computed from these files.

Disclaimer

The descriptor and notes are reproduced from the FY2027 ICD-10-CM files; MS-DRG, CC/MCC and HCC facts come from the CMS FY2027 and PY2027 tables. Code from the medical record and the ICD-10-CM Official Guidelines. Not legal, clinical or billing advice.

Found a figure that does not match the CMS file? Report a data correction with the CMS file and the value you expected; the request reaches the editorial team through the contact form.