O20.0 ICD-10-CM Code: Threatened abortion

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for O20.0 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Notes without a marker are published on O20.0 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for O20.0

MedCoder structured workflow — derived from this code’s own official record

Before you code O20.0

1. Confirm the condition is documented as complicating the pregnancy, childbirth, or the puerperium, and check the trimester where the code carries one and the fetus character where the category requires it. Chapter 15 codes belong on the maternal record only and take sequencing priority over codes from other chapters. It is the provider’s responsibility to state that a condition is not affecting the pregnancy; the trimester is assigned from the documentation (Guidelines I.C.15.a, I.C.15.a.1, I.C.15.a.3).

   Guide: How to choose an ICD-10-CM code →

2. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with O20.0. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

   See the official tabular notes

Choose the right path

1. Does the documentation support a condition named in O20.0’s Excludes1 note?
   Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
   No → Continue.

Consider O20.0. Then confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement

Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).

Trimester

Assigned from the documented trimester at the encounter, or the trimester in which the condition developed for inpatient stays (Guidelines I.C.15.a.3).

Official instructions as workflow

• Excludes1 — check before selecting O20.0(1 note)

  Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with O20.0: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

  See the official tabular notes · Guidelines I.A.12.a

• Excludes2 — not part of O20.0(2 notes)

  Coding workflow: The conditions named in this note are not included in O20.0. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

  See the official tabular notes · Guidelines I.A.12.b

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Indexed Clinical Terms (7)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

• Abortion (complete) (spontaneous), spontaneous, threatened
• Abortion (complete) (spontaneous), threatened (spontaneous)
• Hemorrhage, hemorrhagic (concealed), antepartum (with), before 20 weeks gestation, threatened abortion
• Pregnancy (single) (uterine), complicated by (care of) (management affected by), hemorrhage, threatened abortion
• Pregnancy (single) (uterine), complicated by (care of) (management affected by), threatened, abortion
• Threatened, abortion
• Threatened, miscarriage

Don’t confuse O20.0 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of O20.0 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

• O00— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of pregnancy with abortive outcome moves the case to O00; the two are not reported together unless documented as unrelated.

  Full comparison: O20.0 vs O00 →

• O08— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of pregnancy with abortive outcome moves the case to O08; the two are not reported together unless documented as unrelated.

  Full comparison: O20.0 vs O08 →

• O20.9— Specificity relationship (Review)

  Overlapping diagnoses in the same category.

  Overlapping codes in the same category — the documentation decides which is the more specific fit.

  What moves you there: A record that documents no more than “Hemorrhage in early pregnancy, unspecified” takes O20.9; specificity in the record moves it back here.

  Full comparison: O20.0 vs O20.9 →

• O30— Excludes2 relationship (Informational)

  Distinct conditions — both may be reported.

  A distinct condition — both may be reported when both are documented.

  What moves you there: Documentation of maternal care related to the fetus and amniotic cavity and possible delivery problems adds O30; it is not part of this code and both may be reported when both are documented.

  Full comparison: O20.0 vs O30 →

• O48— Excludes2 relationship (Informational)

  Distinct conditions — both may be reported.

  A distinct condition — both may be reported when both are documented.

  What moves you there: Documentation of maternal care related to the fetus and amniotic cavity and possible delivery problems adds O48; it is not part of this code and both may be reported when both are documented.

  Full comparison: O20.0 vs O48 →

• O98— Excludes2 relationship (Informational)

  Distinct conditions — both may be reported.

  A distinct condition — both may be reported when both are documented.

  What moves you there: Documentation of maternal diseases classifiable elsewhere but complicating pregnancy, labor and delivery, and the puerperium adds O98; it is not part of this code and both may be reported when both are documented.

  Full comparison: O20.0 vs O98 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Verify Before Coding

• Age-restricted: the Medicare Code Editor lists this as a maternity (age 9-64) diagnosis; other ages are presumed incorrect.
• CC as a secondary diagnosis (FY2026). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name O20.0 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Excludes1 note: O46 — Antepartum hemorrhage, not elsewhere classified (via O20.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 247 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 6 MS-DRGs: DRG 817 (MDC 14), DRG 818 (MDC 14), DRG 819 (MDC 14), DRG 831 (MDC 14), DRG 832 (MDC 14), DRG 833 (MDC 14).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):PRG009 — Early, first or unspecified trimester hemorrhage (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

O14.04 — Mild to moderate pre-eclampsia, complicating childbirth, O14.05 — Mild to moderate pre-eclampsia, complicating the puerperium, O14.14 — Severe pre-eclampsia complicating childbirth, O14.15 — Severe pre-eclampsia, complicating the puerperium, O14.24 — HELLP syndrome, complicating childbirth, O14.25 — HELLP syndrome, complicating the puerperium, O14.94 — Unspecified pre-eclampsia, complicating childbirth, O14.95 — Unspecified pre-eclampsia, complicating the puerperium, O16.4 — Unspecified maternal hypertension, complicating childbirth, O16.5 — Unspecified maternal hypertension, complicating the puerperium, O20.8 — Other hemorrhage in early pregnancy, O20.9 — Hemorrhage in early pregnancy, unspecified, O25.10 — Malnutrition in pregnancy, unspecified trimester, O25.11 — Malnutrition in pregnancy, first trimester, O25.12 — Malnutrition in pregnancy, second trimester, O25.13 — Malnutrition in pregnancy, third trimester, O25.2 — Malnutrition in childbirth, O25.3 — Malnutrition in the puerperium, O26.10 — Low weight gain in pregnancy, unspecified trimester, O26.11 — Low weight gain in pregnancy, first trimester, +226 more

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Early, first or unspecified trimester hemorrhage).

O20.8 — Other hemorrhage in early pregnancy, O20.9 — Hemorrhage in early pregnancy, unspecified, O26.851 — Spotting complicating pregnancy, first trimester, O26.859 — Spotting complicating pregnancy, unspecified trimester, O44.10 — Complete placenta previa with hemorrhage, unspecified trimester, O44.11 — Complete placenta previa with hemorrhage, first trimester, O44.30 — Partial placenta previa with hemorrhage, unspecified trimester, O44.31 — Partial placenta previa with hemorrhage, first trimester, O44.50 — Low lying placenta with hemorrhage, unspecified trimester, O44.51 — Low lying placenta with hemorrhage, first trimester, O45.001 — Premature separation of placenta with coagulation defect, unspecified, first trimester, O45.009 — Premature separation of placenta with coagulation defect, unspecified, unspecified trimester, O45.011 — Premature separation of placenta with afibrinogenemia, first trimester, O45.019 — Premature separation of placenta with afibrinogenemia, unspecified trimester, O45.021 — Premature separation of placenta with disseminated intravascular coagulation, first trimester, O45.029 — Premature separation of placenta with disseminated intravascular coagulation, unspecified trimester, O45.091 — Premature separation of placenta with other coagulation defect, first trimester, O45.099 — Premature separation of placenta with other coagulation defect, unspecified trimester, O45.8X1 — Other premature separation of placenta, first trimester, O45.8X9 — Other premature separation of placenta, unspecified trimester, +14 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main terms “Abortion”, “Hemorrhage, hemorrhagic”, “Threatened”; these codes share that main term but sit in a different category of the Tabular List.

O07.32 — Renal failure following failed attempted termination of pregnancy (attempted, complicated by, uremia), O07.33 — Metabolic disorder following failed attempted termination of pregnancy (attempted, complicated by, metabolic disorder), O07.34 — Damage to pelvic organs following failed attempted termination of pregnancy (attempted, complicated by, laceration of pelvic organ), O07.35 — Other venous complications following failed attempted termination of pregnancy (attempted, complicated by, venous complication NEC), O07.36 — Cardiac arrest following failed attempted termination of pregnancy (attempted, complicated by, cardiac arrest), O07.37 — Sepsis following failed attempted termination of pregnancy (attempted, complicated by, sepsis), O07.38 — Urinary tract infection following failed attempted termination of pregnancy (attempted, complicated by, cystitis), O07.39 — Failed attempted termination of pregnancy with other complications (attempted, complicated by, specified condition NEC), O07.4 — Failed attempted termination of pregnancy without complication (attempted), O08.1 — Delayed or excessive hemorrhage following ectopic and molar pregnancy (excessive, following ectopic gestation), O26.2 — Pregnancy care for patient with recurrent pregnancy loss (habitual or recurrent, care in current pregnancy), O44.1 — Complete placenta previa with hemorrhage (antepartum, due to, placenta previa), O45.9 — Premature separation of placenta, unspecified (antepartum, due to, abruptio placenta), O46.00 — Antepartum hemorrhage with coagulation defect, unspecified (antepartum, with coagulation defect), O46.01 — Antepartum hemorrhage with afibrinogenemia (antepartum, with coagulation defect, afibrinogenemia), O46.02 — Antepartum hemorrhage with disseminated intravascular coagulation (antepartum, with coagulation defect, disseminated intravascular coagulation), O46.09 — Antepartum hemorrhage with other coagulation defect (antepartum, with coagulation defect, specified defect NEC), O46.90 — Antepartum hemorrhage, unspecified, unspecified trimester (antepartum), O47.0 — False labor before 37 completed weeks of gestation (labor, before 37 completed weeks of gestation), O47.1 — False labor at or after 37 completed weeks of gestation (labor, at or after 37 completed weeks of gestation), +215 more

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

Partial Thromboplastin Time (PTT) Test, Pregnancy Test, Prothrombin Time Test and INR (PT/INR)

Contextual Map

Every relationship of O20.0 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run O20.0 with this related code in Claim Check

Hierarchy

• O00-O9A — Chapter 15: Pregnancy, Childbirth and the Puerperium (O00-O9A) (O00-O9A)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• O20-O29 — Other maternal disorders predominantly related to pregnancy[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Referenced by Excludes1 notes

• O46 — Antepartum hemorrhage, not elsewhere classified[Excludes1](via O20.-): “hemorrhage in early pregnancy (O20.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

• PRG009 — Early, first or unspecified trimester hemorrhage[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

MS-DRG Grouper

• CC — Complication or Comorbidity [MS-DRG severity]: “As a secondary diagnosis this code can raise the stay's MS-DRG severity tier (CC).”— CMS MS-DRG Definitions Manual (Appendix C) · FY2026
• DRG 817 — OTHER ANTEPARTUM DIAGNOSES WITH O.R. PROCEDURES WITH MCC[MS-DRG]: “OTHER ANTEPARTUM DIAGNOSES WITH O.R. PROCEDURES WITH MCC (MDC 14)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 818 — OTHER ANTEPARTUM DIAGNOSES WITH O.R. PROCEDURES WITH CC[MS-DRG]: “OTHER ANTEPARTUM DIAGNOSES WITH O.R. PROCEDURES WITH CC (MDC 14)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 819 — OTHER ANTEPARTUM DIAGNOSES WITH O.R. PROCEDURES WITHOUT CC/MCC[MS-DRG]: “OTHER ANTEPARTUM DIAGNOSES WITH O.R. PROCEDURES WITHOUT CC/MCC (MDC 14)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 831 — OTHER ANTEPARTUM DIAGNOSES WITHOUT O.R. PROCEDURES WITH MCC[MS-DRG]: “OTHER ANTEPARTUM DIAGNOSES WITHOUT O.R. PROCEDURES WITH MCC (MDC 14)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 832 — OTHER ANTEPARTUM DIAGNOSES WITHOUT O.R. PROCEDURES WITH CC[MS-DRG]: “OTHER ANTEPARTUM DIAGNOSES WITHOUT O.R. PROCEDURES WITH CC (MDC 14)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 833 — OTHER ANTEPARTUM DIAGNOSES WITHOUT O.R. PROCEDURES WITHOUT CC/MCC[MS-DRG]: “OTHER ANTEPARTUM DIAGNOSES WITHOUT O.R. PROCEDURES WITHOUT CC/MCC (MDC 14)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

MDC crossing

• MDC 14 — Pregnancy, Childbirth and the Puerperium[MDC crossing]: “Pregnancy, Childbirth and the Puerperium — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 94 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

• Abortion (complete) (spontaneous), spontaneous, threatened[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Abortion (complete) (spontaneous), threatened (spontaneous)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Hemorrhage, hemorrhagic (concealed), antepartum (with), before 20 weeks gestation, threatened abortion[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Pregnancy (single) (uterine), complicated by (care of) (management affected by), hemorrhage, threatened abortion[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Pregnancy (single) (uterine), complicated by (care of) (management affected by), threatened, abortion[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Threatened, abortion[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Threatened, miscarriage[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes

• O20 — Hemorrhage in early pregnancy[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• O20.8 — Other hemorrhage in early pregnancy[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• O20.9 — Hemorrhage in early pregnancy, unspecified[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Change history

• FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data

CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page

Claim edits Official source data

CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page

Inpatient payment groups Official source data

CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page

Change history and date-of-service validity Official source data

CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page

Comparisons, relationships and the contextual map MedCoder structured relationship

Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears

Summary and FAQ answers MedCoder explanation

Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Nearest Codes in This Family

Official ICD-10-CM classifications closest to O20.0 in its code family, with their registry titles.

• O20 — Hemorrhage in early pregnancy
• O20.8 — Other hemorrhage in early pregnancy
• O20.9 — Hemorrhage in early pregnancy, unspecified

View all codes in the O20 family